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The Trouble with Treble, A Space O.D.D.Y.S.Y. (Read 580 times)
RFZ_Quest
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The Trouble with Treble, A Space O.D.D.Y.S.Y.
09/11/17 at 04:17:57
 
The Trouble With Treble, Resonance, and Everything In-Between:A Space O.D.D.Y.S.Y.

1). Assuming that you do not intend to alter your room dimensions, or 2). Build a room-within-a-room for perfect sound isolation, and 3.)That your room dimensions are too small to meet the criteria of standard quadratic diffusers, then this is really the best alternative means that you have to choose from to get the best possible results from your audio room, or at least get on the right track to getting there.  (Golden Ratio anyone?........there's a thought.)

As you can see, the size and shape of your audio room really does make the decision for you as to what it needs to be correct. If you can possibly measure your room with an RTA analyzer, that is always a great place to start, and a very good tool for analyzing your room as you make acoustical corrections. There is an App you can download to your Android to do this. Just Google it.

Here's something to think about. So what should be obviously clear by now is that there is a wicked problem already dominating your listening space and it is like the proverbial wolf at your doorstep, just waiting to ruin your day. That "wolf" translates into room modes which wreak total havoc throughout your entire space, destroying any hope of understanding of what your music could really sound like from your system (and just how good your system really is). And the funny thing as completely ridiculous as it is, the first thing people want to do is exacerbate the problem even further by adding a sub-woofer, or yes, the ultimate solution, a bigger amp to crank up that volume, and thump that lumpy bass into oblivion!

Oh yeah!, that will sure fix the problem with those pesky room modes and give you the REAL bass response that you always wanted. There's nothing like drowning in a crashing wave of distorted, bloated, underwater-thump-in-a-trash-can-effect that sounds soooo incredibly realistic and pleasing. Someone please give me some aspirin, my head hurts from all that awesome bass!
  Smiley

As bizarre as that analogy is, you know this is a common issue, and don't even get me started on those mobile retards that rattle your brain from several car lengths away in traffic. When you consider the source, and that trash they actually call music, well it really doesn't matter for them. That whole scenario is a train wreck which derailed from the start.

The definition of room modes as quoted from Wikipedia; "Room modes are the collection of resonances that exist in a room when the room is excited by an acoustic source such as a loudspeaker. Most rooms have their fundamental resonances in the 20 Hz to 200 Hz region, each frequency being related to one or more of the room's dimensions, or a divisor thereof."

Well, the cause and effect is pretty straightforward, but what can be done about it? Just like Steve has the familiar tag line"If the first watt sucks, why continue?"........What I must ask is, If the room response already sucks, why make it worse, and pretend that the room isn't the problem? What was that familiar saying about the definition of insanity? Well, there is that thing called ignorance...which is forgivable, but when it is ignored and repeated, it is just plain stupid, let alone crazy.

If you are trying to seriously improve the acoustical anomalies of an inherently bad small listening room, then forget about killing your upper end frequencies with over-absorption, and unless you have the required space between you and the back wall, which should be dominated by diffusion, then consider an alternative option to standard Q.R.D. diffusers, as they need lot's of space to diffuse properly without producing artifacts which become another problem on the list. Q.R.D.'s (quadratic-residue-diffusers) are a great solution if you have a room large enough, otherwise you are just spinning your wheels in the mud and going nowhere. This would be like trying to test a nitro burning dragster down your driveway, there just isn't enough space to get the job done! Do not misunderstand me, as Q.R.D's are still superior when it comes to non-absorbtive diffusion coefficients. What I am trying to reinforce is that even though Q.R.D.'s are the best performers, they simply are NOT the best choice in small confined areas, for which so many listening rooms are restricted in size. No matter what they say, size ALWAYS matters.

Each room's acoustical situation is different, and each will require a different rate of frequency transformation. This will have to be determined through careful room measurement to see what range of correction is going to be optimal for your room situation.

The quickest way to destroy your listening experience is with over absorption at the critical higher frequencies, and the upper-mid-range frequencies which don't take much to alter their structure. You need to concentrate on the troublesome lower bass frequencies where the real culprit to bad sound is lurking....those lower registers extending down below 300 Hz, and into the sub-bass regions where you must surgically isolate with absolute precision in order to control the room modes which are never really dissipated completely, but they can be tamed to an acceptable degree if done right. In a small room, the trouble begins around 300 Hz, and becomes severe below 100 Hz.

The problem is trying to do this without destroying the room's ambience by over absorption of the higher frequency band. Remember, the higher the frequency, the shorter the wavelength. It takes very little to absorb a 20 kHz wavelength, but it takes an unacceptable amount of absorbant barriers to even TRY to slow down, let alone STOP a 20 Hz wave, which is an omni-directional force compared to the beaming nature of the higher frequency.

You would probably have great sucess stopping a bee in flight with a playing card, but just how effective is that playing card against a charging rhino? Whereas you are going to need some very powerful stopping force to control that rhino, you certainly don't need a bulldozer to challenge that bee! Without the bee, you will have no honey. Let's not kill the bee in the process of taming the rhino.

This writing will attempt to cover the major requirements concerning the control of room modes, but what ALWAYS matters here is that the true demons within the room MUST be removed with extreme prejudice before ANY serious acoustic modeling can even begin to take place with diffusers or anything else. If you are serious about music quality, then perhaps you should stop following a false hope of replacing equipment in order to provide the answer, and actually FIX the problem that will NEVER allow any piece of gear regardless of price or Godly influence to perform the way it should. I mean....really people, stop denying the room as an issue, and put your money where it really counts!

How do you think your recordings would sound if the studio that made them was inside of a 14 by 16 foot room with bare concrete walls, merely covered with foam wedges, and several panes of glaring window glass, not to mention the low ceiling, and over-absorbing (critical high frequencies) carpeted floor? I can guarantee you that studio wouldn't get much business, and i doubt those recordings would ever get a second listen, as they aren't worth the media they are recorded on. So be realistic, how is that scenario any different from the average untreated room that people tend to ignore as some trivial afterthought?  Just how well do you want to enjoy your music anyway? And hey, have you really ever heard the TRUE potentual of that BIG buck system, and what those speakers can really sound like when properly set-up within a balanced room?

Sadly,I would bet that less than thirty percent of self proclaimed audio "purists" have ever even come close to an ideal listening room. They only hear what the limitations of their room set-up allows, and the only insane race to the cure is spending more money on the delusion that "better" equipment is the answer to the problem. This really opens up a huge Pandora's box of lost hope. Mediocre equipment in a well balanced room will sound superior in every way to ANY equipment in a bad acoustical setting, regardless of snob status, and the amount of cash paid to the dealer who promised you this newest design would be the end-all to your fantasy holy grail of audio perfection....that is until the next greatest thing comes out. Well, this does seem to keep the audio rags, and the major audio retail industry in business. You need to learn how to walk before you can run.

Trust me. Once you experience audio truth, not only will you set the music free, but the music will set your senses free to ask yourself...just what WAS I thinking! I know what you will be thinking once you unlock the secret which has evaded your perception of stereo playback all of your life. You will probably be upset that you have been missing out on all of this. It's not too late, today is another day, and you can change that. Now, as if the room problems aren't disaster enough to deal with, the dilemma gets even more whacked with inferior, or incorrect speaker design!

So you think you have a great set of speakers do you? Perhaps you may want to re-evaluate what you have just to make sure they aren't actually part of the problem. If you actually grasp the value of the following information concerning critical design parameters, and how the laws of physics work either with you, or as in most cases, against you, then you should be able to understand why the speaker design itself is of utmost critical importance within the room it interfaces with. If you are not willing to accept that fact, then I can't help you, nor will anyone else. Either learn the hard way, or pay attention, and finally understand what has been evading your listening quality all of these years. WOW, this roller coaster ride of unscrupulous mediocrity just continues to fool consumers into that labyrinth realm of never ending promise. "Really, the bass is kinda weak at my favorite listening position (probably right smack in the center of a null zone), guess I just need bigger speakers with HUGE 15 inch drivers, and throw in a big 'ol sub-thumper for good measure"  Yeah, that will do it, because the audio salesman promised me that would make me happy! Boy, I can't wait to get this stuff home and crank it up in my little 14 by 16 foot room with an eight foot ceiling....gonna be soooo good right? BOY, is the joke on YOU! Oh, I know, let's just fight fire with fire, and shoot beams of sound all over the room erratically from the ceiling and walls. Hell, that'll be so good that you will just forget about the original problem.  Uhhhhh...Okay...as you wish!

Listen to me carefully, once your room acoustics are corrected, and acceptable as an ideal listening space, the next thing you must understand is that if your speakers are not appropriate for your listening space, to include PROPER placement, AND they are NOT an ideal match to the amplifier driving them (or vice-versa),then your hope of superior sound is already D.O.A.! Just remember, you can spray paint a turd with gold paint and cover it in glitter, but it will always be just a turd, and nothing more. Don't use a turd for an amplifier, or your music will sound exactly as what is driving it. If you don't dial in the exact area of speaker to room synchronicity, you haven't even found the starting line yet. (And don't forget about the 38 percent listening position which I will cover later) The following is a quote which very well sums this up.

"Synchronicities are those moments of meaningful coincidence when the boundary dissolves between the inner and the outer. At the synchronistic moment, just like a dream, our internal, subjective state appears, as if materialized in, as and through the outside world. Touching the heart of our being, synchronicities are moments in time in which there is fissure in the fabric of what we have taken for reality, and there is a bleed through from a higher dimension outside of time. Synchronicities are expressions of the dreamlike nature of reality, as they are moments in time when the timeless, dreamlike nature of the universe shines forth its radiance, and openly reveals itself to us, offering us an open doorway to lucidity."

Man does this excerpt reveal the full context of what we need to achieve in our listening experience! This was written by an author by the name of Paul Levy, as he relates to Jung's contributions.

You have to realize that for a given room size, just like any other formulation of compatibility, there is an ideal speaker size for the room size it is to load with pressure, and sustain that pressure level without strain, yet not exceed the maximum value required by the room's volume. Compatibility and balance is crucial for optimum room loading. This combination has to be a match to be effective together.Obviously, a driver that loads a small room perfectly with very impressive results, will come up short of doing so in a larger room. Imagine this as blowing up a balloon. It takes a certain amount of volume to fill an average room, which will be quite effective for that purpose. Now take that exact volume of air, and transfer it to a much larger balloon.The larger balloon is going to barely inflate enough to even lift off the surface, while the smaller balloon it had previously filled would have exploded under pressure if that limit was increased. This is what is happening when we exceed the appropriate driver size within a given room's volume. While an 8 inch driver will load a smaller room with full bodied presence, it would produce far less performance in a room fifty percent larger. Only when the listening space volume grows, does the demand for proportional growth in the driver's output and stability. When we have to start driving things harder, there is always going to be stress and fatigue where endurance becomes a factor. On the other hand, let's not over inflate the safe limits of the smaller room. Make sure that your speakers are designed for the listening space for which is expected to give you the results that YOU expect. By that regard, the opposite is true.

Make sure your drivers are big enough to sustain the desired loading of the larger space as well. Exacerbating room modal problems is the last thing you want to do, as you are going to have a hard enough time resolving the bass issues already in place.  Fix the low frequency cancellations, and bloated peaks within the frequency response of the room, and you will have the most incredible bass you ever heard as the reward, that is IF your speakers are up to the task.

Much more information, details, and images to follow. Please hold.
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RFZ_Quest
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Re: The Trouble with Treble, A Space O.D.D.Y.S.Y.
Reply #1 - 09/11/17 at 04:23:20
 
I would appreciate it if everyone holds all comments, questions, and postings for now, until I can continue writing this article which will take me several days to complete.  I think most of you will find many interesting points brought up here, and this should be helpful for those trying to learn about room acoustics. Thank you for your consideration. This article has much more information to be displayed as I can get time to write it.  ;)
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RFZ_Quest
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Re: The Trouble with Treble, A Space O.D.D.Y.S.Y.
Reply #2 - 09/11/17 at 18:11:16
 
Chances are that you already have enough bass in your room, you just haven't released it's hidden potential yet. You will be amazed at relatively how minimal the amplifier levels need to be in order to drive this new resolve at the levels of room output you wish to obtain. Probably less than you were using before, and with more pleasing attributes of bass quality.

Your amplifier doesn't have to work as hard when the room is responding favorably to your speakers. I do not need special cables blessed by the supernatural, nor do I need a better amp, or even a better source, and I damn sure don't need a better set of speakers, in order to make MY listening experience better. Once you obtain a matched configuration with optimal performance, is it really a necessity to go beyond what already is ideal?

There comes a time when this all makes sense and everything falls in place. You just have to understand how, and when to recognize that fact. Do you FEEL the dynamics of your music, and are you intimate with the rhythm?  If not, why not?

Let's think about this in another way....just a little applied physics and rationale to see a clearer path. Everyone can relate to automobiles to some degree, so, from that viewpoint, let's examine a scenario which reminds me of the over bloated bass syndrome.

We know how teenagers think they have reinvented the wheel, and somehow they seem to know more than the design engineers that created their car. But, within all their infinite wisdom, they can make it better! (so they think) Well in some cases, there are ways to improve due to the very fact that the designer had to comply with budget restraints, safety regulations, longevity, durability, warranty limitations, and among other things, responsible liability.

Sure, it is always fun to modify the engine to create more horsepower and torque, but there are limitations before many variables come into play and a change of balance really effects the rest of the car in ways that just are not up to the task beyond the stock configuration.

The theory comes to mind that hey, wouldn't it be awesome to stuff the biggest motor we can into the lightest car possible? Could you just imagine how fast this thing will be?, and who cares how it handles, I just wanna go fast and blow everything else off the road!

Now imagine this little car introduced in the late seventies designed to be an economical grocery “gitter” with a very small aluminum based motor that produced the equivalent horsepower of a few good mice frantically chasing a piece of cheese in a squirrel cage. Well, it got great fuel economy right up to about the time it met it's premature death, as the aluminum block would wear out due to the abrasion factor of the piston rings within the cylinders, causing it to burn oil like it was on tap from an Arab's back yard. This was a great example of GM engineering; The Chevy Vega...wow what a piece of work that was! There were a lot of very dissatisfied owners who bought into that lemon.

Now to be fair, the idea was good for the changing times, but in all it's engineered glory, you have to wonder how these brilliant engineers fell so short, right off the deep end.  Now you can imagine, there was a good supply of these late model shells parked in shame around the country, either awaiting sale, or a complete engine overhaul or replacement. It wasn't long before the gear heads got the bright idea of turning these low budget fragile bodied cars into lightweight mutants of excessive cubic inches, with sheer horsepower designed for a car twice it's size. Well there is a huge difference in the design factors of a  factory equipped 302 c.i. '69 Z/28 Camaro, and that of the 3-rodent-in-a-squirrel-cage Vega.

You know someone's gotta do it!! Yes, but not simply by stuffing a V8 into the cramped confines of the shoe box engine compartment. Not hardly, if this was ever going to work, then this car was going to need complete transformation in order  to execute all that power, and not disintegrate instantly under load.

By the time this was a car worthy of the motor within it's chassis, the only part of this car resembling an actual Vega was the nameplate and the body panels it was displayed on. Every single component within the drive train modified, complete modification, and transformation of the frame an absolute must, brake assemblies, suspension, wheels, tires, the rear axle, transmission, you name it, it had to be upgraded and re-engineered if was to be a success.

In the end, it was a doable goal with some pretty interesting results, but doing it cheaply or easily was nowhere in the description.

Hmmm, well then, yes, you might go fast, fast straight into the path of failure if there is a fault within the entire build process. Crash and burn, or ride into victory...you decide.

The first step is to rectify the detrimental standing wave issue within the room, this is the ugliest of all demonic forces which keeps you from hearing your system the way it should be perceived.  

The most important relationship in the room is the marriage between the speakers and the room itself. If all they do is argue and fight each other, then perhaps it is time for an intervention, and counseling, before it all ends badly in divorce.

Where to start the primary focus is in the corners of the room, ALL of them from floor to ceiling. This is like building the track before the train itself. You have to have a path for the train to follow without getting derailed.

I strongly recommend a diaphragmatic panel design ( pressure absorber ) that acts like a spring to absorb the lower frequencies, while reflecting the delicate higher frequencies that can be killed way to easily, rendering the room void of any spatial qualities. That is a key element to success, I really hope you were paying attention!

Pay absolute attention here and FORGET what some of those dummies on YouTube are telling you (there are a few exceptions). My god there is some really bad advice floating around in cyberspace!  Sort of like being invited to a Kool-Aid party in the jungle to hear the gospel from Jim Jones.

That is exactly why I am spending my precious time trying to bring light to real substance concerning correct acoustical measures that actually have scientific value. If only a few of you listen, at least a few more people will be less ignorant about the facts.  I don't know what upsets me more, unscrupulous audio dealers who thrive upon the ignorance of people who simply trust what ever marketing scheme sounds the best, or that consumer who just chooses to remain ignorant, and feed the machine of deception.

Ignorance is fully acceptable, education is your cure.  Insanity is NOT acceptable, there is no cure for that....then there is just plain stupid!

Anyway, aside from that bitter tangent, you can listen to this critical fact, or just do as you please and fix your problem with some new equipment.  Do NOT under ANY circumstance place open face absorbent in the corners of your room or on the walls themselves, and THINK you have the problem under control.

Number one, if you really knew how this all works in the room, you would know that the bass problem you are trying to subdue is one of a PRESSURE problem. That being the case, as I will explain in great detail further on, the only way you can control pressure, is with a pressure loading device capable of decoupling that pressure from the room, and your music.  You need the absorbent INSIDE of the pressure type (diaphragmatic), but definitely NOT touching the face panel, and absolutely NOT being exposed to the room itself. The pressure absorber must be sealed to work effectively anyway.  When you simply stuff huge wads of nasty fiberglass into the corners, or onto the walls of the room, they are doing much more harm to your acoustics then they are helping.

Any room with this done to it is going to be dull and lifeless in the upper frequency band (and guess what genius...you haven't fixed a damn thing!). If you can't tell the difference, then perhaps your hearing is shot, or your system really needs some major improvement.

Anyway, by doing this, you still won't control the very core of the bass problem, and now you have made things even worse by destroying your ambiance, and critical detail.  Way to go sunshine. Hey, it's okay, you can still fix it.

Other than that, slat absorbers, or perforated absorbers, are going to be the most effective devices you can use if they are designed to meet the actual needs of your room. Not only will be these perform in superior fashion with high predictability, but most importantly, they will absorb ONLY where needed, and preserve the delicate balance above those frequencies with reflection, which then in turn will be tamed with diffusion.

To prevent over absorption, which is the baseline rule to adhere, stay away from those cheesy worthless foam pads that go on the wall, and avoid large areas of open absorption which just sucks up far more of the good things in the room than the bad.

Do you want to be influenced by total chaos and bad atmosphere, or would you like to listen in peace with total lucidity and resolve? I think that answer is clear...so you know the truth, don't deny it with excuses or ridiculous countermeasures that are absurd at best.

I actually took the time to design some very practical Helmholtz-principle-based-perforated-absorbers for you to build, designed to work together across each octave in a seamless manner where the problem is the worst in a typical room situation.  I will post a few of these design models later down this post so that you have the information to build them.  These work in narrow range across the audio spectrum, that is why more than one design must be employed, and in a way which overlaps for consistent full coverage.

These along with the pressure type bass traps should do it for you in most cases.  For starters, please do yourself a favor, and fill in all corners of your room top-to-bottom with sealed diaphragmatic panel absorbers. Then add the perforated absorbers, preferable at the front of the room, since it is well served there. A few of these placed below the wall of diffusion on the back wall  is also vital. The back wall will as a minimum, have full corner traps, but is heavily treated with diffusion . Utilize the two concepts together as much as possible within your back wall zone. Do not add more than is necessary to flatten out your frequency response. Just make sure that you add enough to make your room stable.

Remember, the diaphragmatic action of the corner bass traps must remain unrestrained to allow spring action. Nothing can be touching the face panel. Otherwise they will not work. They transform the bass through resonance of frequency.

Cancellation always occurs at ¼ the wavelength from your wall, regardless of the phase of the wave hitting the wall. Why? Because at a quarter wavelength from your wall, the total travel difference (for a wave reflecting back on itself) is half a wavelength. This means the reflected and direct sound are 180 degrees out of phase.

When two sound waves of equal magnitude are 180 degrees out of phase, phase cancellation occurs — they cancel each other out because they are equal and opposite. So, if your direct and reflected sound waves are similar in strength, and half a wavelength out of phase, the wave-forms collide to cancel each other out. Just like an atomic melt-down, nobody wins.

This is called speaker-boundary interference response (SBIR). This means big trouble, like Darth Vader's Death Star, the killer weapon being boundary-induced-comb- filtering, and it will obliterate your room.

SBIR causes deep dips in the bass response below a certain frequency, and it can affect your low frequency response even more than room modes. You better understand one simple fact: your speakers will only perform as well as your room boundaries allow them to. Your room accounts for the absolute structure of the music quality conveyed.  Your room acoustics are, and always will be, the dominant factor in how your system sounds. Perhaps this is why there are so many differences of opinion about equipment evaluations. These people aren't actually evaluating their equipment, they are evaluating the ROOM!

Don't even think you are going to correct SBIR using EQ. Newton's third law is: “For every action, there is an equal and opposite reaction”. The result of using a “correction” filter in an attempt to boost the frequency at cancellation, results with the consequence of also boosting the REFLECTION which is the main culprit of the interference!  WHOOPS!  No magic pill for you today young apprentice.  


Look, the only way you can completely avoid speaker boundary interference is by flush mounting your speakers into the front wall. Or at the very least, build a second wall outward of the wall behind the speakers and flush mount your speakers into that false wall. In essence, you have just modified your speakers, morphing them into an infinite baffle, and you have truly performed a marriage between your room and your speakers. Now all they have to do is produce beautiful music together!

This remedy just got rid of your speaker diffraction problem.   Since it is assured that most people are not going to go as far as major room reconstruction, then you have to make a compromise, and do the next logical thing.

There's gonna be a few who are going to twitch a bit over this suggestion, but that's okay, get over it and understand that you are not always aware of what's best in every single application. I know this to be fact because I've proven it through extensive testing parameters. I didn't have to summon the audio gods to channel a notion of what I might have thought to be better. The truth was immediate, pronounced,  and completely obvious within it's increased accuracy of  the natural frequency response.  Let's see, instant clarity, vibrant sensation of the music, allowing you to FEEL the music as well as hear the notes with absolute distinction (oh, and did I mention full body, and a sense of being one with the music?). This will achieve higher SPL using less amplifier power to drive the same intensity. In essence, the room boundaries and the speakers have reached an acceptable form of agreement.  The logical assumption is that previous frequencies which were canceled out among those that were exaggerated, have found new harmony within balance. There is a leveling out of peaks and dips within the lower registers, and now the sound is heard the way it was meant to be (not to mention the physical presence). It is not perfect, but at least things are starting to make sense.
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RFZ_Quest
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Re: The Trouble with Treble, A Space O.D.D.Y.S.Y.
Reply #3 - 09/11/17 at 18:13:08
 
Please stand by, there is much more to come. Thanks for stopping by! More information to follow shortly.
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RFZ_Quest
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Re: The Trouble with Treble, A Space O.D.D.Y.S.Y.
Reply #4 - 09/11/17 at 20:06:53
 
What happens is that as you locate your speakers closer to the vicinity of the wall, the cancellation notch in the frequency response raises upward into the higher registers. Being that higher registers are more directional with decreased rear radiated energy, they become far easier to manage with acoustic treatment.

This close proximity placement also helps to drive the speakers with more output, and less distortion. Another cause and effect is the result of low shelving, in which to increase the bass response. I know this to be true from actual testing and evaluation. It has made a tremendous difference for me, and the result is very satisfying.

I do want to note, that I am seated at the prime spot in the room where the lowest degree of room modes can inflict their damage to the music. That spot being equilateral to the speakers at the 38 percent line from the front wall backward. Theoretically, this area is determined as the best listening position within the room. I have to agree, it makes a dramatic difference.

Arrange the room to be as symmetrical as possible. If the room is A-symmetrical, then it can cause the sound to also be A-symmetrical, which degrades the sound-stage. This asymmetry can manifest in a few ways: one is uneven bass response (if there is a much larger area to one side then the bass will be different there than in a small area). Another is that if one side wall is further from the other, then reflections to that wall will have further to travel to hit your ear, which means they will arrive later in time. This can also contribute to an unbalanced stereo image.

FIRST REFLECTION POINTS......next to taming the room modes, and this can't be stressed enough, If you are serious about truly knowing what lies deep within your recordings, perhaps much of which will surprise you of it's existence, then you better stay awake and not skip out on this mandatory measure. This, and  the “removal” of inter-aural cross-talk, is none less critical toward the improvement of your room, and it will make just as significant improvement to your room quality as that of bass traps.

 If you bought the most expensive equipment in the world built by an alien race of superior advancement, it probably wouldn't give you the rate of drastic improvement for which this very simple correction will give you (and with far less cost). NOW IF THESE SO CALLED ADVANCED ALIENS WERE SMART ENOUGH TO DEVISE A SOLUTION BETWEEN THE AMPLIFIER AND THE SPEAKERS in order to cure the detrimental damage caused by inter-aural cross-talk, then THIS WOULD BE THE EXCEPTION.

Actually, if you think about it in the realm of advanced science and technique, I would have to imagine that beings this intelligent would devise a totally encompassing formation of ”symbiotic relationship” interlinking a symbiotic human machine interaction, or perhaps “technological singularity” which is already a viable concept at the hands of D.A.R.P.A. The very room itself emits perfect sound through the transcendence of space and time in the form of perceived alpha waves....no need for speakers...hey problem solved, no speakers, no inter-aural cross-talk!  Geez, if only the answer was that easy and obtainable.

Maybe in the future, but doubtful in my lifetime, and I have some music to listen to in the meantime. Just have to make the best of what primitive earthly technology affords us for now. Hey, maybe if you shove an android phone far enough up the space where the sun don't shine, you just may be able to download an app for which this interface may be possible. Are you listening Microslop?  Okay, lighten up, and don't take that seriously, just a joke okay?....but just imagine the possibilities.  Now let's resume a rational link to earth and continue.....

Now in theory, this should be a relatively easy problem to correct. Problem: as opposed to sounds perceived in nature, we are detecting cross-linked cues that are confusing our ear-brain system. Instead of naturally detecting sound cues from different points in space, we are actually tricked into focusing upon the location of the speakers, not the actual localization of these original cues. This is the ultimate form of masking, and no degree of amplifier technology, or source implementation, or hair-brained speaker design, is going to correct this without proper configuration to deal with it specifically.  

Solution: Correct the false cue arrival which tricks the brains perception, and cancel it out completely so that only the original cue can be detected by true localization. Our objective is to bifurcate the original cues like two narrow beams of light with absolute precision to your perspective ears. Left ear detects left channel with total isolation from the right channel, and vice versa, resulting in absolute resolve of the problem that plagued us from achieving the truth within the sound-stage image. Sounds easy enough, but just one thing, how are you going to do this?

The reason that audio manufacturers and acoustic device retailers avoid talking about this is because they don't have a clue how to deal with it. If they can't sell you a device to counter it, then it simply does not exist, and is not something you should worry about.  But hey, they have some mighty fine $1200 magic boxes to fix you right up with that bass bloating.  On the other hand, there are those technologies by companies who make their profits exactly on this concept alone.  Bring on the next act.

Hey you, yes YOU in the back, shouting out....”hey that already exists in the form of D.S.P”....uhhhh. please sit down, there are real audio purists here wanting a REAL purists solution. So far, that ship is just a leaky boat with some much further advancement needed before it is ready for prime time. It works, but with consequences of compromise to the quality of the musical form, which is far from acceptable within my perception of quality listening. If you consider yourself a real audio purist, then this absolutely is of utmost concern to you as well. This is the one thing that has yet to be resolved without complex digital signal processing, and very expensive equipment at the top end of the audiophile scale.

What is offered on the lower end of this technology is about as high quality as that of MP3 downloads, which is mediocre at best. I don't want D.S.P. I will settle for nothing less than pursuing Analog Signal Perfection! (A.S.P.) The only device that works without affecting the signal is that of a physical barrier. A design of which can allow the listener to sit further back from the end of the barrier, and actually allow for a second listener to sit directly behind the first would be determined by an equation which dictates the width of the barrier, the separation of the speakers, and the maximum allowance for space between the barrier, and the listener. This equation is stated as: L=X(H+T)÷D. Given in inches, L = max distance of ears to barrier end. X = distance from listening end of barrier to the positional line of the speakers. D = distance between the speaker drivers (center to center) H = distance between your ears. T = thickness of barrier. Your speakers will be as close together as possible with the barrier in between.

With the “MINI-AMBIO” device which uses the R.A.C.E. configuration, coloration does become a factor. A moderate cut in sensitivity also seems to be a factor with a touch of dryness left behind , a reduction within the dynamic depth is noticeable which should be in your music. ( and no, I am not confused with misinterpretation of compounded decibel levels (peaks) for certain frequencies amplified by room modes which may fool my perception of loudness). Give me a bit of credit, this isn't my first time around the audio block, and I do know the difference. If I didn't, I probably wouldn't be writing this in-depth analysis of a real world situation.

If frequency dynamics and low frequency extension are not critical factors for you, then D.S.P. could be your ultimate ticket to success. So far, it has not earned a badge of merit in my system concerning the total picture. Not something you want when you just spent thousands of dollars to create clean, well focused sound.

This uneven frequency response is caused by reflected sound waves bouncing around the room and interfering with one another. In some places and frequencies, these sound waves reinforce each other causing a peak; in other places they cancel each other out causing a null. Usually the most severe peaks and nulls are related to the room modes (frequencies related to the room's dimensions), but there will be peaks and nulls in many places throughout the frequency spectrum. Be warned that severe nulls are located at wavelength points of ¼, 3/4, 5/4, etc., from the rear wall. These null-zones are little agents of evil that will create so much havoc to your frequency response that it will look like an elephant just stepped on a spider-web. It just won't hold up! If you encounter any of these null points, you will be severely disappointed, as your bass response just disappeared through a black hole in space. Any chance of decent frequency response in those zones went right with it. Better avoid those areas like the Bermuda Triangle.

Make sure that neither the speakers nor the listening position are in a place with a severe null point. If this is so, then the speakers will be working harder just to reproduce frequencies that can't easily be heard. As a result people tend to turn up the bass controls, or the overall volume to compensate, which makes the amps and speakers work harder, likely increases the distortion of the system, and only amplifies the unbalanced frequency response. WTF!!!

When the speaker is close to a wall, some of that energy is reflected back toward the speaker, and the reflected bass wave can interfere with the new bass wave that is just leaving the speaker, causing the same sort of frequency anomalies seen above. Changing the distance between the speaker and the wall will affect how the SBIR behaves. Do not however, let this fact sway you to believe that it is never a good idea to place a speaker within close vicinity to the wall. There are some exceptions, and my room-speaker combination proves this relationship to make the best compromise within my room dimensions. My speaker design was developed specifically to work well in this type of arrangement, and boy does it ever!

There are many factors which dictate the end result which are very complex. It is up to you in order to find out what placement works best in your situation. The concept of the “38 percent” listening area is that it is determined to be the least effected area from peaks and nulls. This is definitely the right place to start in order to achieve the flattest frequency response as possible. Do NOT get near the center point of the room, as that is absolutely the worst position to be in. You will have virtually zero bass response there. By the same regard, do NOT sit close to the rear wall, as that is just as bad, except instead of severe bass suck-out, you have massive standing waves building up like Mt. Everest with the worst bloated bass you can imagine. The idea is to get things sounding as even as possible before we install treatment, which then puts you in the best possible position to get a superior sounding room with a good treatment strategy.  Unless you live outside the realm of natural physics, your room is going to have an abundance of uncontrolled sound energy that needs to be dealt with.

Adding bass traps reduces much of this excess sound energy, thereby reducing the amount of acoustic interference that happens in the room. The more traps (not really traps, but you get the idea) you add, the closer you will achieve your goal by reducing interference, thus flattening the frequency response of your room. In an ideal world, a perfectly flat frequency response equates to a perfect perception of your room, and your music.  Well, unless you are really lucky, or you have some type of magical powers, then this is unlikely to happen, but you can get close!  

A rectangular room is comprised of 12 corners in reality. All intersecting boundaries must be added into the equation where the walls, ceiling, and floor all intersect at EVERY point. Bass build-up is always prevalent in corners and it isn't particularly biased as to which ones it hides in. This all adds up to one major problem.

As will be explained later, Q.R.D. sound diffusers require a great deal of space for the full bloom to take effect throughout the scatter-bloom-diffuse cycle, with around ten feet being a good average distance.  Another reason for arranging your listening position to no less than 10 feet from the rear diffusive wall, goes back to room modes, and how they affect you. With at least a 10 ft. space away from the back wall, you are in a safer zone with a wavelength cancellation frequency that is below 30 Hz. Many of you don't have systems that go lower than that, or even approach that depth. At any rate, you will at least be rewarded that opportunity for full disclosure once your room starts telling you the truth. You will be amazed at what information unravels deep within your recordings once the room is correct. You will be saying recording after recording, Man, it is as though I am listening to an alternate version of the recording with allot more notes, and far more delicate detail, with clarity and precision which I never thought possible. No, same old recording. That information has always been there, you just never heard it before.

Here is a funny, yet common scenario based upon ignorance. If this applies to you, then you better listen up. Don't be offended, there is an entire industry feeding upon this type of ignorance, and the internet is just a good system for the virus they generate to corrupt the truth. Learn to identify what works in reality and ignore the rest.

So, a common mistake that some people quickly want to believe in, is the “magic cure” for their room troubles, that being those pretty wedge shaped foam squares that just are SO easy to apply, and don't they just fit in with my so important décor!  Oh lord, sounds like a sugar in the shorts convention. Now there is going to be severe consequences by doing this concerning your room acoustics. If you just listen to an all in one table radio, then who cares. For the rest of us with serious intentions, we need to avoid this for reasons which will be identified further within this writing.

Stay tuned....more to follow.
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RFZ_Quest
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Re: The Trouble with Treble, A Space O.D.D.Y.S.Y.
Reply #5 - 09/11/17 at 21:02:25
 
In a nutshell, You are only killing the uppermost frequencies, leaving the real destructive force intact. This really screws up things, creating a very unpleasant sounding room that has no life, just the sound of a bloated whale slamming around a restricted tank trying to get out. Very disturbing to your senses, and far from anything someone would find enjoyable.

Are you beginning to get the picture? Alright, so I assume that is why you are reading this in the first place, so let's see what we can do about your room.  

The first thing the listener hears is the direct sound leaving the speaker and traveling in a straight line toward the listener's ears (at least with normal speakers you do). Then, a few milliseconds later depending on the size of the room and how it is arranged, the listener will begin to hear first reflections, where the sound leaves the speakers, bounces off the side walls, the ceiling, and the floor, and then hits the listener's ears. Note that these reflections are not 'late' enough to be perceived as a separate echo (unless you have a very large listening room); rather they all converge and our brain tries to interpret them as the same sound. This means that for each speaker, we hear essentially the same sound coming from five different places (direct from speaker, left wall reflection, right wall reflection, ceiling reflection, floor reflection).  

Since the reflected sounds are not 'late' enough in time to be perceived as a separate sound or echo, all that happens is our brain's ability to locate where the sound is coming from gets confused.  Perhaps Steve's interpretation of the “EGG” diffraction is playing a phsycological role in how its “perfect shape” is distributing these cues spatially? What do you think Steve....perhaps?  “Just how many licks DOES it take to get to the center of a tootsie pop? The world may never know.

With mainstream equipment which is mid-grade or lower, this extra coloration is not going to matter, and the benefit actually outweighs the compromise. If you don't understand why this is so, then you better learn, or just continue fooling yourself into financial oblivion trying to chase that elusive pipe dream of audiophile absurdity for which seems to reinforce profitable delusion.

Let me put this in better perspective just in case this isn't getting through your helmet. Your room, and your speakers have created the ultimate conspiracy for which to feed your brain with mis-information (sounds surprisingly familiar to a certain government agency huh), brainwashing you to believe through conditioning, that what you have always experienced is factual reality. Trust me people, NOT EVEN CLOSE!

Oh, and by the way, thinking of those fancy speaker schemes designed to provide an “alternative” measure to somehow cure all of these problems, but in reality, only exacerbating these problems within your listening space, this picture comes to mind. Carelessly reflecting false images around the room in “omni-directional” fashion is like inviting a pack of hungry raccoons over to dinner. They really are amiss of etiquette, and they are such devilish creatures of destruction and mayhem. But they were so cute!  Add multiple drivers to this list of hopelessness and you really have a recipe for disaster now. Not in my room you don't! If you don't mind, I prefer accuracy, and control with true localization, not colorization. To insure that, I shall adhere to proper speaker design, build quality, and logical set-up.  Did someone say “acoustic lobing”? And don't you just love those comb filtering effects! We are trying to suppress the reflections we have now, not add more problems and call it a balancing act. Reinforce the K.I.S.S. Principal!

Again, companies get rich fooling the uninformed consumer with products of false claims and deception based upon utter non-sense, which goes against the grain for the ultimate goal, any serious audio purist wishes to achieve. It really just depends upon how serious you really are about musical accuracy, and proper localization within your advanced level of perception, adapting to higher levels of reality.

There is only one natural way to perceive true audio, there are no alternatives....period! If supernatural speakers and cables are your choice, just put your blinders back on and forget about all of this....it just doesn't matter for you.

Can you imagine buying the latest high definition television which promises the highest quality image and focus ever imaginable, just to get it home and realize that things are not what they appear to be, or at least what SHOULD appear to be.  I mean, what is this all about? I am supposed to be seeing one centrally focused image of perceived reality in this large area with sharp believable detail, but instead, this picture is actually two separate halves of the image, split, and overlapped at the center, and skewed off out of balance.

Now my eyes are working double time (pun intended) to formulate this split image of deception, as to how I should perceive this image in reality. No matter how hard I try to focus, this is always going to force my mind to see it as two independent sources that are out of balance. You are not going to enjoy this set, and you will most likely develop a very bad headache from attempting to view it. You did not get what you bargained for!

If this makes you angry and feeling ripped off, then why doesn't this scenario anger you after spending thousands of dollars on over-inflated claims of three dimensional abundance, just to find out that the end result is not really up to your expectations of reality, and knowing the reasons why according to the laws of physics. Yet another victim taken on a ride into yet another cold, dark alley of audio deception.

I guess you have to spend a few more thousand of hard earned dollars to get the holy grail...and then again, you have to wonder.  There are those of you that believe you have what is promised, and then there are the few that really know the difference. Do not let ignorance and deception lead you down another dark alley, just to get robbed and left in the cold.  Arm yourself with knowledge, the kind of knowledge which has actual confirmation of experience to back it up.

If you know the truth, you won't be deceived for your money anymore.  You can if you want, but you know the saying about a fool and his money.  The equation is you, your room, and your speakers. Once you solve for the solution, you won't be searching any further to find the truth.....I expect the fool to scoff, and walk away about now...that's okay dummy, the audio dealer is calling you.

The single most difficult anomaly that we must deal with which really is the hidden secret to unlocking the mystery of real localization is that of inter-aural crosstalk.  This is like the final frontier for which modern technology is just now finding a viable way to control this destructive portrayal of misguided sound cues (everything from D.S.P., to binaural recordings, to head tracking software, is a reality to combat this phenomenon). This is the true beast which lurks within your perception of factual information which should be perceived from your speakers, but is not. As I stated before, this is a phenomenon which simply does not exist in real time, but is the result of playback through audio speakers on to your ears for which things get really screwed up in the process, and you simply do not receive the correct information concerning spatial cues like you would have naturally. This is the most complicated problem to deal with, and options are very limited. No matter what else you do to your room, what speakers you have, or the quality of your amplifier, none of that matters until you correct this problem, which will NEVER let you hear what you should be hearing, until you accept this fact as reality, and do something about it! More on this problem later.  

By using the right choice of acoustic panels at the early reflection points (sidewalls, ceiling, and floor), you stand a great chance of drastically improving your rooms clarity of detail and wide open ambiance....space, the final frontier, to go ….sorry, got off track....music without dimension isn't worth listening to, and if you think it is, then save yourself the time, money, and hassle, and just listen to your iPod and head phones, or perhaps a table top radio will suit you just fine..what is the point if you fail to do this correctly? Well, you never know, perhaps you just need a more expensive source or better speakers....surely something I can't see could be tangible enough to make such a difference, perhaps this acoustical engineering thing is all just imagined psychobabble BS, or that of pseudoscience madness!  Hmmmm....is it?

Well, if that is where your mind is at, then you deserve what you get, because your situation is just right for you.  For the rest of you that do understand, then press forward, you have work to do and much to gain from it. Generally once you have enough bass traps, and a solid Reflection-Free Zone, you are poised to have a nice tonally-balanced room, and pinpoint imaging from your system. If there are any remaining trouble spots where you can hear flutter echo or something similar, you can always add additional spot treatments to deal with them.

Just like about anything else in the scientific world, opinions can really add confusion to an already complex situation.  I for one am not here to argue or take sides. I know what I strongly believe in and hey, I am not about to debate what I already know is my best choice.

Sometimes compromise is in order to reduce conflict, perhaps one must examine conflicting theories to see the strength within both, before committing to bias..once again, your world is yours to do as you please. Just remember, not every technique works in every situation, that is why we take alternative measures, but only when they make sense and have true value.

So, with that said, There is conflicting bias among the acoustic crowd concerning where diffusion and absorption play out best within your listening space. The first argument is between what is best for the first reflection correction technique on the side walls. I hear it often that the best recommendation is to use absorption judiciously to eradicate that side reflection dead in it's tracks. Sounds reasonable, right? At least one would logically come to the conclusion that if this side reflection is bad, then wouldn't it be best to eliminate it entirely?

Then perhaps, just perhaps, a thought occurs.....Yes, minimizing speaker diffraction is key, but, if this side reflection is kept in check by decelerating its rate of arrival in time which in turn, contributes little to no impact upon the direct signal, then perhaps it's new “softened” decelerated presence will present a backdrop of added spatial cues, that now will not confuse your perception as the untreated reflection would, yet add a touch of  welcome ambiance to the overall picture.

Now in a smaller listening space where there is even less area to deal with side reflections in a way that is most effective, then perhaps I may lean toward the idea that sidewall absorbers are the optimal choice simply because there is not enough area for the diffuser to spread from its frequency dependent scatter-to-diffuse ratio in the time domain.

That is logical because you really can't consider standard QRD diffusion in a small space where it simply cannot work optimally. So I guess this leaves us with only the absorption approach to battle this conflict...or is there an alternative approach?    Wait...here it comes, oh yes, yes there just may be a way to have your cake and eat it too!

Okay, so we are discussing the problematic worst case scenario here, trying to acoustically balance a small listening space plagued with very serious issues that are going to require some trial and error to make this space acceptable. Not impossible, but complex.  So what other choice is there that is going to be possibly better than simply using an absorber panel.

What makes sense to me is a hybrid design that offers both absorption AND diffusion with the ability to do it in short distances with relatively good results. The thing we want to avoid is over usage of absorption exposed to the higher frequency range which will suck all the life out of the room, therefore being counter productive to the attributes of anything else you do from that point forward. Doesn't really make sense to have that new $7000.00 amplifier capable of the most phenomenal detail and resolution, along with all the other gear matched to complement that ability, just to place it within a dull lifeless atmosphere that sounds like you have very poor recordings that will bore you to sleep.  

This is where I can see the greatest advantage point of using a curved binary amplitude diff-sorber, which is an optimized two-dimensional binary sequence offering uniform diffusion over a wide frequency range with natural absorption as part of it's function. The binary face plate is diffusive above 1000 Hz with pure absorption below that point, which is just what we need in order to provide reflective properties with absolute preservation of the room's ambiance. Why are we interested in using a curved version of the B.A.D. Panel? Because the curved surface breaks up specular reflection which occurs from the flat version of the same panel. This shape influences all of the reflective areas to no longer be in phase with each other, resulting into an improved polar response. Naturally, a higher diffusion coefficient occurs.  A very noticeable gain within the listener's “sweet spot” provides a greater sense of ambient dimension.

With your speaker baffles flush within the wall surface. Your front wall becomes a giant speaker baffle. An infinite baffle. If your speakers are placed in front of your wall (as opposed to flush-mounted in the wall), boundary interference will always be there to mess with you. You may not be able to avoid SBIR completely, but you can position your speakers to minimize the peaks and nulls that wreak havoc on your sound.



More to come shortly....please stand by.
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Re: The Trouble with Treble, A Space O.D.D.Y.S.Y.
Reply #6 - 09/12/17 at 01:44:23
 
The perfect solution is to flush mount your speakers directly into the wall, but that isn't very practical for most people. If you are building a audio room from scratch, I highly recommend that you do this. The next best thing is to build a false, rigid wall, away from the existing wall to create the same virtual effect in which to encapsulate the speaker boundaries. This also aids in becoming a natural sympathetic bass trap if it is sealed airtight.

Make your wall thick with multiple layers of construction. At least two sheets of drywall sandwiched with a sheet of plywood between should work very well.  Think ISOLATION, and all the factors that create isolation from the rest of the room. Do what is necessary to stop transfer of lower frequencies into your house beyond that isolated boundary. It must be sealed airtight. Vacuum makes a very good sound suppressor.

This may be a good time to consider a false floor to provide additional bass trapping, and isolation from the main floor, again to cancel transfer of low frequency energy. Think of a sealed platform floating above the primary floor.

And now, a word about nodes.

What is an Anti-Node?...according to the dictionary as related to the world of physics, an anti-node equals “ the position of maximum displacement in a standing wave system”.

An anti-node is a point of maximum amplitude where constructive interference occurs. Whereas a node is point of minimum amplitude where destructive interference occurs.





The depiction of the crest and trough to represent the pattern is used to help identify the length of a repeating wave cycle. A standing wave pattern is not actually a wave, simply just a pattern of a wave.  Crests and troughs are exaggerated, nodes and anti-nodes are very real. This pattern is the result of the interference of two waves to produce these nodes and anti-nodes.



The drawing below depicts a theoretical layout within an average room which gives you a very logical place to start from. The blue sphere represents the listeners prime position within the room for optimal frequency response, and least amount of interference from standing waves. You should find within this vicinity, that your room really comes alive with clean strong bass, and extended low frequency content rich with detail and presence, rather than the one-note bass line. If you are only going to implement minimal room acoustic corrections, then at least use this layout and just see if it does anything to improve your listening quality.

Now you have to take into account that there are many variables which can affect this layout, namely the type of speakers used, and the degree of bass trapping placed in the corners, and behind the speakers themselves. I can tell you from experience in trial and error, that this set-up really does educate you about modal problems, and especially just how good your speakers really sound within your room when placed ideally.



Oh yes, I can hear the naysayers now, proclaiming their infinite wisdom concerning the closeness of these speakers to within the proximity of the front wall.  Yes, but to a point.  Remember, we are talking about a small room here with limited real estate to work with. Now if this had been a focus upon a much larger listening space, then of course, we would naturally want to take advantage of that space and move everything out away from the walls as much as possible, but in relation to where room modal problems won't be at their worst. So, How do you get away with this close proximity in a small room. It is a matter of compromise, but you will find that it really does work for you if careful placement is complied with.

First of all, we know that speakers will generally produce a rear wave which will work its way around to the front of the speaker where it meets the corresponding front wave. Low frequencies are omni-directional so you can imagine. If the speaker and room condition allow these two equally opposing waves to meet simultaneously, then it is like the titanic, and disaster is imminent with complete cancellation of the frequencies involved. Your low frequency response just sinks to oblivion. Peaks and dips are like a battlefield, allot of bad things are gonna happen with only one outcome, and it is bleak. Bass cancellation is the last thing we need to have working against us. The 38 percent line is paramount as a starting point to achieving success.

Our best defense; the quarter-wave rule. You must obey the Minima / Maxima law. Cancellation is guaranteed at ¼ the wavelength from the wall, and the phase condition of the wave at impact is irrelevant. You want to avoid that like the plague! This condition was discussed with the identification of S.B.I.R. Simply put, we are acting like the floor is covered with land mines and we are being careful not to set one of them off. Remember the nodes and anti-nodes? They are the little land mines present all around the room just waiting to destroy something.

By far, the most serious offender responsible for the destructive interference of our perception of localization is inter-aural cross-talk. If you don't correct this situation, I guarantee that you will never hear the real cues faithful to natural spaciousness which occurs in nature. Why is that, because your speakers are responsible for this as is the rest of the artificial process of reproducing an original sound wave or signal content within the waveform.  This phenomenon exists only through your sound system on playback. Inter-aural cross-talk creates comb-filtering which as we know is a very evil enemy to realistic music perception. There have been many ways in which attempts have been made to correct for this problem. I remember in the mid eighties when Polk Audio actually injected a signal out-of-phase from one channel into the other channel and vice versa for the SDA series in order to provide cancellation of the cross talk signal. I heard them back when they were new, not bad, but still not the magic bullet.

Even more successful was the electronic scheme that physicist Bob Carver patented in his very successful sonic hologram generator with auto correlation control. I had this unit back in the eighties and it did indeed work well for me. Now back then, even though that equipment was considered very good by mainstream standards, well, it sure wasn't going to qualify in the minds of audio purists with unlimited funds to spend.  Make one thing clear as of now: I DO NOT WANT ADDED D.S.P. IN MY SIGNAL CHAIN....PERIOD!  Any serious audio purist live by that motto.

Back in the mid-eighties, I had used the auto-correlation circuit with mono-block solid state M1.0t amplifiers, and Acoustic Research(AR9's) speakers anyway. So the balance of equality was about the same. The one exception was that my source of media playback was totally analog, and natural. I would transfer virgin copies of vinyl directly on to my AKAI 747 DBX type I studio grade reel-to-reel for endless playback of very nice sounding recordings.  I really wish I hadn't sold that reel to reel in the name of digital modernism...one of the worst mistakes I ever made in audio! My problem with that is that I am against any form of extra electronic manipulation within my signal path. It is bad enough having to deal with a digital source.  Additional signal processing will add as many problems to your waveform as it attempts to correct.  Kind of like the crap these doctors and pharmaceutical companies are constantly jamming down our throats in pursuit of the almighty dollar!  That poison they are peddling produces more side effects and damage than the “cure” it was designed for.  Well, it really isn't that different for audio, and the detrimental artifacts just keep influencing the signal chain, and always with a degree of consequence.  Remember the K.I.S.S. Rule....Keep It Simple Stupid!

One of the more favorable attempts that I have heard was right from the source of the recording studio where a technique called “Q-sound” was implemented to combat this problem.  Man, if all recordings were done this way, it would go along way to solving many issues with playback.  These completely blow away standard recordings. Too bad there was a very limited library of those recordings. I wish somebody like Steve Hoffman would start a new studio that records direct from the master tapes, and reissues all the great albums in a technique similar to this.  I think there is a good market there. But then again, the hassle and expense of licensing fees, etc.  I sure enjoyed his contribution to vinyl reproductions on DCC records.

Today the closest thing to resolving this issue is through bin-aural audio recordings using the dummy head technique, and again, electronic manipulation with concepts such as ambio-phonics, which I thought seemed a very promising way to correct this problem, even though it would mean the injection of DSP to color the original signal, and that is pure evil in my book. Don't urinate in my filtered water, and tell me it is fancy lemonade! Oh, and yes, we have even entered the technology of real time head tracking devices just to keep things in perspective!  That is if you can fund such outlandishly expense equipment in order to make it your own personal experience. This technology is currently forbidden in my budget.

So, I have evaluated the (mini-ambio) device which goes between your source and your amp, that you set up with your laptop. After many attempts to prove any valuable gain from this device, I only ended up with mixed feelings about the end result. And yes, I set everything up by the book and followed the instructions to the “T”. This device utilizes the R.A.C.E. concept which indeed does exactly what is claims to do.....BUT...at the expense of tainted fidelity, and dynamic authority. It does seem to overly tame the room response a bit in the attempt to create a “flatter” room response. The primary purpose of this device is to remove the unwanted inter-aural cross-talk, acting like an invisible barrier shield between the speakers, and it does indeed accomplish this objective very well. The offset signals that create the confusion upon arrival to the ears are eliminated at the source, therefore no barrier is required physically to stop and redirect those flawed false cues.

I will say this, if you don't mind a little coloration, and a noticeable loss of dynamics ( I estimate around 6 dB ), then you might really find this to be an acceptable, and welcome addition to your system. If you don't plan to do anything to your room for acoustic correction, then at least consider this device. It is far better to use this device than try listening to an untreated room. This is not one of those blind listening tests where three out of five people think they heard a difference, but a dramatic affirmation to all listeners whom are swayed by its direct change, immediately, and with great surprise.  When you are using high resolution amplifiers, source material, and speakers, this becomes quite apparent. For lesser grade equipment, I doubt the negative influence would be noticeable. It is like comparing standard DVD, to Blue-Ray players...something along that line.

Now I can tell you that there was an obvious change in how the sound-stage was perceived, and how there was immediate influence to the room's spatial perception. Think of it as a dedicated time lens, because that is how it functions. But I can't tell you that the results were completely favorable.  Now this I'm sure makes a dramatic improvement with mediocre equipment in a really bad acoustical setting. But when you reach a higher caliber of quality and performance,  played in an “above average” acoustical setting, then you quickly find that this digital enhancement scheme is unfortunately contributing to degradation of the signal, in a trade off for the gained improvement...sort of like the pharmaceutical dilemma, you have to decide if the benefit outweighs the consequences in compromise to the purity of your source signal. If you have a $7000.00 amplifier designed for utmost purity, and transparency, and equally as much, or more in your source and speakers, then you may want to keep additional sound processing out of the loop. Keep it simple, keep it pure.

The solution is going to have to be a mechanical one, and definitely not one which colors the source signal. Maybe the only pure way to rectify this problem is through the recording process at the microphone level. I am not ready to buy into any other scheme that I've heard about just yet. I would rather just park a large physical barrier between the speakers and be assured of a corrective fix to this cross-talk, but then again, this really isn't practical now is it?  

Perhaps an invisible force field that can go up on command between the speakers location would be in order...hmmm, anybody working on that project yet?  Well hey, perhaps a carefully designed “binaural” helmet which will block out those pesky unwanted signals and allow access only for the right channel to reach the right ear and vice versa, wow, I can just see it now!  

But wait, hasn't that concept already been done...why yes, I believe they call those headphones!  This is why so many people prefer to listen to headphones, and for good reason. But, let me tell you one thing with absolute assurance, listening to headphones is in NO way the same as experiencing this phenomenal concept when executed properly. You have been granted access to the truth within recorded music, and things will never be the same! Restriction to headphones is not what I want, and headphones aren't going to bring resolve to my form of stereo listening, so there is going to have to be a another solution.

More on the subject of Localization to come.....
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RFZ_Quest
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Re: The Trouble with Treble, A Space O.D.D.Y.S.Y.
Reply #7 - 09/12/17 at 03:08:26
 
If you have ever played a sound passage of dialog through your home theater receiver listening to your main speakers, while simultaneously having the sound up on your TV monitor at just about the same level, some very disturbing results are going to mess with your mind. Naturally there is going to be a time delay between the two outputs, and of course, there is going to be a confusion between the two sources of output, one seemingly an echo within the other, kind of like watching an old Japanese Godzilla movie with English overdub...lips are moving, but the perception is way out of sync!.  Really crazy when your monitor creates its own phantom surround image within your actual room surround set-up.

This will be extremely convoluted, and just trying to deal with this conflicting nonsense will give you a massive headache with the urge to quickly bring it under control. Well in this case, the cure is easy, simply remove the conflict and the problem is solved.  Mute the monitor source and allow only the perceived signals from the receiver-speaker set-up to be heard. No more confusion, and the dialog is easy to follow. Sweet clarity never sounded so lucid.  

The purpose of this analogy was to give perspective relative to the detrimental influence of cross-talk, coinciding with “out of control” room reflections, and how it influences your perception of the actual timing cues within space and time, the way that sound naturally occurs outdoors from real sound sources. This of course is referring to localization, and that takes us into a whole other area of understanding. By now, you should understand that this is a very real condition with very real consequences. So, what do we do about it, and what should I expect to gain from this phenomena?  I will no longer accept this pathetic oversight by audio manufacturers as something that I just have to deal with the way things are. NO, this is not acceptable, and you are not going to pull that blanket of incompetence over my head and tell me you are just trying to comfort me. I demand better, and if I have to achieve this level of truth and purity within the delineation of simpler mechanical means, then so be it. At least I know and understand what the perception of reality is, through the discovery of music on a much higher level of cognition, the way it was meant to be.

Have you ever seen a really awesome holographic projection, one that looks so vivid and real, yet obviously transparent and phantom? (just imagine how quickly this imagery would be taken from your sight by the simple placement of an obstruction to the projecting lens)  If you have, this is the treat you are about to embark upon with a proper room set-up, and of course, the “fix” of removing this cross-talk, very much like “turning off” the entangled signals from the monitor which were time smearing the stereo sound from another source. Your brain has a hard time differentiating two paths of the same signal at almost equal magnitude when there is a conflict of the arrival time colliding into a barrage of confusion at your ears (we are talking only mere milliseconds here). It really is that simple, and you really will notice a huge difference in your field of auditory perception. Instead of hearing a small imprint of a man walking a short distance close to your head, what you will now perceive is that same man walking from the forward side of you, clearly walking past your location and circling a path well behind your head from a good distance away across the room. Your mind will focus on the clarity of every footstep as he walks directly behind you, and passes to the other side of the room while at the same time, a woman walks up to you from the other side, and whispers directly into your ear with such vividness, that you can almost feel the breath from her lips. And all of these cues in space clearly unraveling with equal perception and balance...or to be technical, localization, a powerful missing link which will now be perfectly interpreted without doubt to its relevance.  

If you want this time lens to remain in focus, you MUST listen to your speakers within a “sweet spot” (which will be wider than before) by means of room, and listener synchronization using a carefully measured, and accurate equilateral triangle (not the traditional 60 degree spread, but a much narrower twenty degree spread, or less) with YOU directly centered within its focal “lens”. People have reasons for not wanting to be limited by this narrow range, but hey, they also make up excuses for not wearing a seat belt...well, it doesn't take an astrophysicist to see the correlation there. Look. If you want to defy logic and do it your way, then again, you might be better off sitting in the corner listening to your iPod through those little ear buds.....it's all the same....right?

It should be clear as to the importance of room configuration “equidistant” measurements. In other words, think of a billiard shot on the table, now think of that same shot mirrored 90 degrees proportional to center. Well, all things considered, the timing and path should be equal and without difference. Now do that shot again, and this time, just randomly make the shot at the other side of the table in a general vicinity of the previous side. What do you suppose the outcome will be?  If you can't see this picture formulating within your imagination, WOW, then this probably won't matter to you anyway.  SYMMETRY IS EVERYTHING THAT MATTERS!

Something you may want to think about carefully while considering added absorption to your room. Many of you will already have one factor in place that you can change, but most will choose not to, so this must be factored in for it's degrading influence upon the delicate, and extremely critical high frequencies. Carpeting, along with variables such as type of carpet, and thickness of carpet, the same applies to the under padding which is even more of an absorbant sponge.  Remember, it doesn't take much to over absorb the life from your room's ambiance. Believe it or not, the carpet you already have installed just may already have killed it, or least dulled it.  This isn't always the case, but you better make sure it isn't a factor that can't be compensated for.  Either deal with it, or pull it up, and put down hardwood flooring.  You only need a few thick rugs primarily where the first reflection points are from the floor bounce. The difference could be like wearing ear plugs (and not) when it comes to the delicate detail found within the upper registers. Music without treble is as interesting as music without bass....clean bass that is!

And then of course, what about all the pre-existing elements within the room, such as windows, window  curtains, your over stuffed listening chair...etc.  By the time all these factors add up, you have got just as big of a disaster creating an unbalance on the top end as you have on the bottom end.

Well, unless you like listening to your music with a trash can over your head, and a blanket over that, while a barrage of marshmallow rubber bass assaults your senses into mass confusion, then you might want to carefully measure, and design ALL aspects within your listening room.

You will only be rewarded by the degree of what you have put into it. Oh, and if you are one of those who believes there is a quick magic cure to all of this through implementation of room correcting software or some type of artificial EQ, then please, if you are not going to pay attention and learn something, then just take your iPod elsewhere and go back to sleep.  I am sure there is bound to be some genius somewhere who is going to enlighten me on that one!

How would you like grease smeared on your clean windows, rendering you blind to that beautiful view outside?  Early reflections are the recipe for disaster, with comb filtering in play, creating “time-smearing” just like that grease obstructing your view outside. Comb filtering is an acoustic anomaly which poisons the context of your music, masking the delicate detail, and oh no....here it comes again...preventing LOCALIZATION. No accurate musical content for you sunshine! Get out the window cleaner, you want to see again!!!

Concerning the Reflection-Free-Zone; this is like the magic shield which keeps initial reflections in check. To accomplish this zone, we need to create an extended delay between your speakers direct signals, and the evil first reflected sound impinging upon your senses which colors the actual message, insuring that you receive exactly what was created in the original form. This delay is called the Initial-Time-Delay-Gap. Now your brain comes into play, and tries to perform complex calculations in order to provide the precise location between perception, and the original signal location, or simply put, an estimation cue for traveled length and origination. In an ideal situation, the I.S.D. gap would guarantee an untainted first reflection intentionally meant for you to hear, doing it in time to cancel out the nasty first reflections of your ROOM not your music.

It would seem that just about every reputable acoustic professional is steadfast on insisting the use of pure absorption to treat the sidewall first reflection points in order to bring this factor within compliance.

Who am I to argue their point? I guess the truth lies directly within the pudding, and we have some taste testing to do in order to find out what solution is best in our room. Try it both ways, (there is the argument that diffusion is better) but I am sure they know a good deal to back this recommendation up with solid acoustical data, and real world listening tests. You decide, it is your room. It just seems to me that by completely absorbing this reflected energy, rather than merely slowing down its delayed presence within a shower of diffused state, that there just may be something special removed within the spatial cues. Again, I am only speculating.  Now if you are stuck with a small listening space, there is not going to be enough space between your walls to get any benefit from pure diffusion at these points. Therefore, pure absorption makes perfect sense.  A large room with the correct ratio will perhaps allow it.

For an intermediate solution that may or may not give you an appreciable compromise between the two methods, is that of a curved (out-of-phase) binary amplitude diff-sorber which naturally uses absorption to produce diffusion above 1K with a softer, diffusion coefficient than what non absorbtive diffusive devices offer, but able to give results within a much shorter time-span, making it viable for controlling reflections within a small space.  Just a thought. And wouldn't this be an ideal spot to try out the ternary diff-sorber design?

Whatever you do, never, NEVER, kill the ambiance within your room with over absorption at higher frequencies. You might as well not even bother trying to make your room sound better when you do something as self destructive as this situation will do against all of your trouble, time, and expense to make things right.  Sort of like hiring the blood thirsty wolf to watch over your chicken coup.  Hmmm....better not put those fancy foam things on the wall, I think they may be a wolf in sheep's clothing....ya think?  This is why I don't want to place exposed absorbent in the room that will soak up the delicate information, any more than is absolutely necessary.

We want as much controlled absorbent as possible to ACTUALLY combat standing waves WITH the ability to block absorption of the upper frequencies, always keep that in mind. I don't need a howitzer in my house to kill a fly on the wall!

Oh, and those snob appropriate over priced magical cables aren't going to help you one bit to fix these major problems. It would be wise to start with clean, stable power FIRST before you worry about exotic cables, and hey, did you ever really examine the actual quality of those crossover filters hidden within your speakers? Remember the weakest link syndrome, there is nothing more matter-of-fact than that. If you are going to go to the extent of using over priced supernatural cables, then finish the job, and see that quality to the finish line.    Let's not throttle up the jets without proven airworthiness, as you are likely to crash and burn. Eject! Eject! Eject!  It's funny, because I remember those “D” ring ejection handles in many different fighter aircraft, and they kind of had that same fancy look to them....and we all know how much the government loves to waste money on things. Hey, perhaps you just need a solid gold chain to turn off your lamp. It could make a difference, right?

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Re: The Trouble with Treble, A Space O.D.D.Y.S.Y.
Reply #8 - 09/12/17 at 04:07:25
 
Oh yes, this makes perfect sense...let's avoid any dealings with room acoustics because it might interfere with your wife's décor, and simply focus instead upon those supernatural audio cables that have been specifically blessed by the Pope, and handed down directly from the Priests of the Golden Audio Society.   You have a long way to go before you should even think about spending your money there.  You would have to have everything, and I mean EVERYTHING in proper order before you could actually extract real beneficial gain out of those cables, compared to what a well designed audio room will do for you. ( The exception is if for some reason you are using really crappy cables bought at the local hardware store) Look, if you understand cable geometry, and use high grade materials, keeping high quality connectors, grounding, and shielding in mind, and most importantly, remove the pseudoscience nonsense, then you already have the best there is...don't think so, let's perform that A/B test and find out.

 Try some professional grade microphone cable, terminated with Neutrik connectors, and snap on some ferrite core noise suppressors, then see how they stack up against something that costs 100 times more, with that prestigious label that every Hollywood star will endorse for the right amount of cash.  For speaker cables, keep the length to a minimum, and go as thick of a gauge as you can get in high purity O.F.C. stranded copper, no less than 12 gauge, and preferably larger. If EMI/RFI is a problem for you, then take it up a notch with proper shielding.   D.I.Y. And SAVE! Caution: Do NOT ever use copper coated aluminum, that is pure evil, and will definitely destroy your quality of sound. Use premium machined plugs, and you will be very satisfied, regardless of all the unproven hype and nonsense to justify the cost of magical cables. Well, I'm sure they produce some mighty fine cables stemming from alien technology grown in a Petri dish, and incubated for just the right amount of time in virtual hyperspace, utilizing vacuum controlled, cryogenic treated transformation, free of all non approved particle contamination! Yeah, okay, sure thing! Allot of money has been profited by that type of voodoo marketing, and there are always an abundance of fools with cash in hand. If you are wealthy, go for it! If you are like most people, spend your budget on proper room acoustics where the biggest return on your investment awaits. The only thing I will buy into concerning worthwhile techniques is that of the benefit for which PROPER cryogenic treatment does to metallurgy  I'm sorry, how dare I undermine the gospel within the audio rag prayer book. I have sinned, please forgive me.

Talk about the very worst cost to benefit ratio there is in audio. You really need to see the light when you have fallen into a hole this deep. And by now as I am sure you are quick to respond in defense of your cable justification, just answer me this one simple question. Are you so sure that you can honestly pick your cables over a sensibly built sane budget design in a direct A/B test ten out of ten times, or for even that matter, just three out of ten times?  Well, you might, and hey, congratulations are in order if that is how you measure up.  However, If we were talking about the same amount of money invested within PROPER room acoustic control, I can guarantee you that your perception of value will be spot on, each and every time!

And for that, I leave absolute zero room for a shadow of doubt. Do your exotic cables last if you really feel justified to do so, but just be practical within your logical approach. At least start with sensibly fashioned cables that will get the job done very effectively without breaking the bank. You can't frost your cake until the cake is ready. Doesn't do any good to pour expensive synthetic oil into that racing engine if you fail to screw the oil plug in.

What about the front wall, behind the speakers...does that need anything? Well if you were to build a wooden boat made of slats and your objective was to insure a safe passage across the water, would you make it very far without sealant to keep the water from entering through the joints?   You better be able to swim!  

Of course this area is crucial no less than the rest of the room in order to maintain balance. You don't run a marathon and stop short of the finish line when you are mere steps from victory.  (oh, and yes, we still have the ceiling to worry about)....getting pretty tiring isn't it?  Just don't be overwhelmed by all of this transformation. Once you experience the end results, you will dwell in musical paradise for as long as you have that room.   If you are still with me reading this far into it, I know that your intentions are serious, and you want this for yourself, and who wouldn't!

With that said, let's tackle the forward wall.  What is the best defense here?  I heard someone out there shouting out...more diffusion.....more diffusion.....hmmm is that right?  From my perspective, I will not tell you that this is wrong, nor will I tell you this is right. Remember, everything is a compromise and every situation is different. Just because I like a particular suit, it doesn't mean it will look good on you.

 So what do we do?  Again, the common belief is that the front area should be treated heavily with maximum absorption. Is that a good idea? Well, it seems reasonable to me, as long as we don't destroy the preservation of balance within the frequency response of the room, and especially being careful with the delicate nature of ambient cues....this has been our main focus all along.  (was that a pun?) Put the rhino in a cage, and let the bee live to make honey.

Considering that we should place some sort of diffusion along the side walls and ceiling, and that we have already tamed the rear wall primarily with diffusion and bass traps, then hey, I suppose this shall be fine in most cases. I on the other hand, would like to step it up a notch and promote the idea of mixing it up.  Yes, you need a very strong defense system to manage this destructive low frequency force up at the front lines, but that doesn't mean you can't add some seasoning to the meal. It's already gonna be great, but that extra bit of flavor just might make it special.

You will be calling in the reinforcements to heavily fortify this part of the battlefield using every means at your disposal to kill this nasty beast, and bury it forever.  Key in the parting dark clouds, and singing angels, as they ride the wave of white light into your room (oh, and the sound of Wagner - Ride of the Valkyries cues up).................

Remember, this is a high pressure area, so tread carefully. This is exactly where you will build a fortress of protection with the diaphragmatic absorbers as corner traps, limp mass membranes, and several strategically placed Helmholtz perforated panel absorbers of different design frequencies, to evenly treat the overlaying octaves as your big guns to bring the beast down.  Please do NOT even think about placing thick fiberglass chunks of exposed absorbant on this wall, or anywhere else in the room for that matter!!  STOP...just don't do it!  You might as well just forget about all of this if you are going to do that.  Think of a wild tiger, he isn't going to hurt you if you trap him in a cage. Just isolate him into his natural habitat and all will be fine.  It just isn't necessary to throw rocks at him. You are just going to get him angry, and you will be his next meal. You have a far better chance of bringing this beast down with extreme firepower, than you do by wrapping a blanket around his head in an attempt to smother his powerful, ruthless attack. Just remember the golden rule!  You MUST use pressure activated devices to control these evil low frequency demons because pressure is all they know, and that is all they respond to!  Enough said, you have no other choice.  You could listen to your system outside in a field, away from every means of reflection and containment, but hey, save that for another day. Oh wait, there just may exist problems there too!

All of this fighting is exhausting, yet we must drudge forward, for the battle is almost won. Look up my young apprentice, for some of those evil troublemakers are perched above us, just waiting to swoop down and irritate the hell out of us....resistance is not futile young Jedi, the dark side must be destroyed!  And now the scene draws near as the Jedi force heavily attacks the dark fortress with every last means at their disposal....if only there was a way in..with just one more strategically placed attack...and there it is, within my sights...that nasty glare of intense reflections trying to destroy me with their deadly beam weapons! Not this time you master of doom...today I am bringing YOU down.

I know that acoustical absorption clouds are very popular today, but they just don't make sense for a small room where it is way too easy to lose the presence of ambient spaciousness.  I am not going to use QRD's because an eight foot ceiling is not going to make those work effectively. If you have a high ceiling over twelve feet, then QRD's are your choice.  So is there an alternative for a workable compromise, yes, and it is the same viable solution that we used to control the side wall early reflections. Time to reveal the latest in acoustical weapons...the highly advanced ternary diffusion system with built in frequency crossover point. You get to decide at what point these devices crossover from upper frequency deflection on to controlled diffusion, and finally, pure absorption.

You have the power to dial these designs in precisely to meet your room's requirements. The working Fo range for these extends from a quarter-wave frequency of 750 Hz, on up through the spectrum.  These just happen to be ideal for ceiling grids, and first reflection points, as well as auxiliary reinforcements for the front wall between the speakers. The data provided for these designs should make it very clear to you as to how this is possible.  Design at will!  Be warned there sunshine, do not get any ideas of selling these devices, or the information, as this design is protected by a patent, rendering it as legal intellectual property. If you are scummy enough to do so, you have been warned, and there will be consequences.  This information is for personal use only, and for educational purposes. No commercial profiting is authorized.  Direct violation will result in a late night visit from the shadow government.



Sorry about the poor quality of the grid information, it just didn't reproduce very well. I will rewrite the information here.

Through a process of folding and inversion, a larger sequence may be developed into the full ternary array.

The final phase of transition, morphed into the finished product yielding a 42 x 48 ternary grid of .5 inch wells.

Frequency is based upon well depth, well width, and dependent upon the thickness of the face plate and its reflective non-absorbent Q-factor.

Performance is limited by these factors. The quarter wave wells must be totally reflective-non absorbent.

Wells are 0.5” square with a maximum depth of 4.5 inches creating a quarter-wave design frequency ( Fο ) @ 750 Hz.

Optional frequency cross-over barrier can be an applied coating hard enough to block upper frequencies.



This should be enough for you to chew on for awhile. I shall return later to continue this posting. There is MUCH more to come!  Isn't DIY FUN! Stay tuned.
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Re: The Trouble with Treble, A Space O.D.D.Y.S.Y.
Reply #9 - 09/12/17 at 20:45:51
 


Polar response scattering shown at the design frequency ( Fο ), comparing three surfaces to include the plane surface shown in red, the uni-polar binary diffuser shown in blue, and the ternary diffuser shown in violet.

*Note: This graph is an approximation based on test data provided by the inventor of this device, therefore it is not meant as an exact representation, but that of a visual aid to help one visualize the difference between these very different surfaces, and their response to incident sound waves.

This type of improvement as shown is a very realistic example of what can be expected between these three comparisons. As it should be very clear, the advanced diffuser design based upon the ternary technique is by far the best choice between these variables. It should also be noted that the uni-polar binary and ternary designs are actually more of a "diff-sorber" technique, as opposed to a standard Quadratic-Residue Diffuser based upon a totally different design principal.

A final word about asborption control devices and some D.I.Y. models to choose from.




The best advice I can give you concerning the designs best for your application, are those that you carefully design for your own particular room problems. Assuming that you are armed with real world test data derived from analyzing your room, then you know what it is going to take to isolate, and concentrate on the areas that really are going to make a difference in your situation.

No two rooms are the same, and every situation is unique.  A superb site that provides some incredible tools for your DIY projects and general education in audio techniques is that of;  http://www.mh-audio.nl/ACalculators.asp

You have access to some terrific calculators that will arm you with necessary data in order to build world class absorbers specifically tailored for your most troublesome room conflicts. It would serve you well to build a corner bass trap for each corner of your room, and it must extend from floor to ceiling, completely sealed off from leaks.

 Go with the panel diaphragmatic absorber which fits diagonally in each corner. Due to high pressure build-up within the corners, you must use an active countermeasure. Simply trying to battle these frequencies here with a big maxi pad isn't going to give you the results you need. You might think it does, but that's what you get from your YouTube education. What was that kid's name again that recommended the pile of fiberglass in the corner?  God, will the ignorance ever cease to breed!

The rigidity and thickness of the panel will determine the frequency of resonance as well as the material coefficient behind the vibrating panel.  A major part of these devices great ability to tame troublesome low frequencies is that of the airtight airspace behind the panel itself. Do not allow the absorbant material behind the panel to come in contact with it.  This panel must resonate and pass off energy as heat to work effectively. Make sure that you use a good absorbant between the panel and the wall. Semi-rigid fiberglass is still one of the highest performing absorbants if used correctly, but it is not health friendly....be extremely careful around it.

This is a viable solution for the absorption of bad modal problems and preservation of the upper frequencies (however, the solution is not limited to this alone)...this is the balance you are looking for.  Now you still have to deal with specific target areas which will require more precise engineering to perform room surgery exactly where you need it, without overkill to areas we want to keep intact.  This is where Helmholtz resonator type designs come into play.

Whether being slat type or perforated, they work well while still retaining a great deal of room reflection to frequencies we don't want to attenuate. I recommend the Helmholtz panel absorbers with perforation as these are easy to calculate, design, and build with very predictable design coefficients.

This design is frequency specific, and spans over a very narrow range, but that makes these ideal for difficult frequencies that just need a very narrow correction.  Remember, it is of vital importance to shape our frequency response across the entire spectrum to be as flat as possible...that is the key to success and you will be richly rewarded for it.

To achieve maximum effectiveness in a velocity absorber, the unit must be located at a quarter wavelength of the lowest frequencies which need to be reduced in energy. An interesting fact to understand is that modal frequencies maintain minimum velocity, and at maximum pressure close to the wall surface. Due to this fact; a pressure absorber (Helmholtz, sealed baffle, membrane, etc.) is more effective at the wall boundary, whereas the velocity type absorber (big overstuffed fiberglass sponge) design works best at a quarter wavelength from the wall boundary.

The velocity type of absorber is one based on large fiberglass absorption panels that simply try to soak up, and absorb some of the bass frequencies. Again, do you really want large areas of open-faced absorption which is going to kill your precious room ambiance? I do hope that you understand that this type of absorption technique only works placed away from the wall at exactly ¼ wavelength of the lowest frequency targeted. Example: you wish to target absorption with a velocity type absorber placed at ¼ wavelength from the wall at let's say 60 Hz. In order to meet that design criteria and be effective, the unit must be placed 4.7 feet from the wall. For an absorption target of 40 Hz, we need the unit placed 7 feet away from the wall! So you see where this is going, right? Just how large is your listening space anyway?  I see people using these directly on the walls. I made that mistake long ago, and corrected that mistake.

We all learn through practical experience. You have to use common sense, and work with the laws of physics, not against them. At lower frequencies, velocity absorbers are impractical for small rooms due to space limitations. The only overstuffed item in your room placed that far away from the walls should be your listening chair, and maybe even that is overkill.

The best way I know of to accomplish this task is through reflective Helmholtz panels which are perforated or slatted, or better yet, sealed active diaphragmatic absorbers, or even limp mass membrane absorbers.

One of the newer designs which Dennis Foley of Acoustic Fields promotes is that of the Activated Carbon Diaphragmatic Absorber. Sounds pretty promising, but considering that one unit costs upwards of $1200 each, I would hope one unit would fix my entire room,...yeah...like that is going to happen.

Yes, I do understand the potential value of this design, and the cost of activated carbon, and it does take allot of it. Still, that leaves a pretty healthy profit margin, and then you have costly shipping to deal with. At this rate, you might have to take out a second mortgage to finance this venture.

I respect, and appreciate what Dennis provides educationally in his series of acoustic videos, and he is a good source of information. But, I would never pay that much for those products, or any other companies products for something as basic as this really is at that cost. I suppose financing would be in order. I don't care if it gives you supernatural powers, and puts you in touch with spirits from beyond, I am not going for it. You can if you like, it is your money. Oh yes, years of money and time invested to bring these products to the market, but hey, let's get realistic and stop overcharging people if it is truly in the best interest to help people out acquiring better sound from their rooms.  Good thing there are people among us who are willing to provide this information in order to actually make effective units at an affordable cost.

Just understand that there is good advice, and there is bad advice. You are responsible for being informed through education and actual research, rather than listening to some young kid on YouTube giving you some of the worst possible advice one can get. Just to clarify, there are a few decent professionals telling you the way it is in reality, but damn, there are SO many misinformed idiots out there preaching the gospel. The deaf, dumb, and blind selling stupid to the world! It would be funny if honest people weren't being fed such inappropriate advice. Take it like a grain of salt and move on.

Here are a few design models which should work well for most cases. These are all frequency specific to help you target the areas you need absorption control limited to.











I do not have a detailed drawing yet on how to build a diaphragmatic corner trap.  Please remind me if I forget to post this in the near future. When I create a diagram, I shall post it for you.


On a good note; guys like Dennis, Ethan Winer, and especially Tim Perry deserve a great deal of credit for providing such valuable information and support to the audio community.  Sure, they like anyone else have business interest in mind, but they also seem sincere in educating those that need the information to take on their own projects.

Not many people have the funding to assemble a world class studio, let alone put a few diffusers, and absorbers in the room. At the price of materials these days, even DIY is almost prohibitive in cost...let alone the time and labor involved.

By this time someone is asking, well what about Steve?  Relax, Nobody has forgotten what Steve has contributed to the audio community. That is why we are here isn't it?  Keep up the good work Steve, you've done well over the years.

 I apologize if anyone took any of this personally or as an attack on their integrity, it wasn't meant that way. The point is, be careful what direction you follow.  I don't have anything to gain from this, so it seems pretty obvious that I am not out to sell you something, or promote anything that I wouldn't use myself.

One more thing, much of what I know would not be discussed here without all the hard work and dedication by D' Antonio, Cox, and Angus. There are many important people in this field, but these individuals have made the biggest difference.

The normal guy is not going to spend that kind of money fixing problems which a good DIY design can achieve for a fraction of that cost. This is exactly why people are turned off when it comes to acoustic devices. There is way too much greed in the industry for one thing. These things are not worth anywhere near what these companies are charging for them. Even if you hire a local shop to make these for you, the price of materials and labor will still be quite reasonable compared to the industry retail price.

And then comes distrust with snake oil advertising full of ridiculous claims and false test results. There is a good share of fancy products that simply don't deliver what they promise.  And then there are those pretty wedgie shaped things that don't do anything but soak up your ambiance and give your wall some artsy flair.....what a shame, and with ignorance breeds deception.....I guess sales are pretty good.

To calculate the axial modes of a rectangular room, one uses the formula:
                                                                       
1130 / 2L = f


“1130” will be the variable determined as the speed sound in feet per second. “ L “ equals the length of a room dimension in which the unit of measurement will be feet.  To solve, “f” equals the frequency of the axial mode in Hertz.

Let's assume for example that a room has an eight foot ceiling, a good example because that is very common in most homes.

1130 / (2 times 8), or 1130/16= 70.625


Between the floor and ceiling, a standing wave exists at the frequency of 70.6 Hz. Subsequently, standing wave's form at the whole number multiples of 70.6, involving 141.2 Hz (70.6 x 2), 211.8 Hz (70.6 x 3), 282.4 Hz (70.6 x 4), etc.

Typical scenario for the standard rectangular shaped room, as you can expect a standing wave located at each of three fundamental axial modes. This entire chain of events result based upon room dimensions, which progressively span across whole number multiples of these frequencies. Get's pretty ugly doesn't it.....just like a train wreck!

Just a quick story which you might find entertaining at best, and one that I don't want you to take too seriously.....but I think it has imaginative appeal for those that like to ponder the possibilities.



That story coming up next......
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Re: The Trouble with Treble, A Space O.D.D.Y.S.Y.
Reply #10 - 09/12/17 at 21:14:45
 
From a post by David Mellor, where he wrote an article called:”What is better for absorbing low frequencies - carpet, or old car tires?”, I found the idea of this to be rather intriguing in many ways.  First of all, thick dense rubber seems logically to be a very good absorber down into the lower frequencies. I have no test data to prove this, therefore I am merely speculating the possibility.  

The real beauty of this possible absorption material, is that there is an abundance of old worn out tires around that I am sure you could get truckloads all day for free.  Now, just imagine if you had a grinding machine that could turn these tires into manageable ground material to be used as a filler within a cavity?  But that not being the case, this still seems quite a feasible prospect as is. Why is that? Because the tire itself is hollow, therefore making it a good sound absorption candidate which can be filled, or not filled as per the required degree of absorption coefficient needed.

Well, nobody wants to look at, or smell old tires, so no, I don't suggest sticking old dirty tires upon your wall and calling it a new art form....you can if you want, but that isn't gonna work in my house.  So why even bring this idea up you may ask? Because, the solution is to use the tire ONLY as an absorbing element for which is the core element encapsulated within an airtight enclosure made of plywood, which now takes on a diaphragmatic nature ( or tailor the face-plate  with the proper calculated amount of perforation per frequency you want to target, essentially making it a Helmholtz resonator).

This is right smack in the design method that we want to use for targeting very low frequencies (the most troublesome), with the most important asset intact....that of reflecting the upper frequencies which we don't want absorbed , therefore maintaining ambient preservation. The thickness and the density of the face plate will determine the frequency crossover point.

It makes sense if you really think about it.  Now, to make it even more efficient, you could leave the tire empty and seal off the wheel openings with plexi-glass or plywood using a windshield type of sealant to keep it airtight, rendering it as a natural spring loaded resonator. An adjustable threaded rod between the plates could be added for fine adjustment to the resonant tension factor.  Just an idea on the cheap!   Thanks for listening, just something to think about.


And now, for the really fun stuff that everybody loves, an indepth look at diffusion principles and practices.  Pay close attention here, and I think you will discover some valuable material  to get you on the right track.  This type of information is rarely given away, but I am taking the time to inform you of what is available, and why it is of interest to you.  I do hope you make use of this information and discover a whole new level of sound preservation once you employ these tactics within your listening space. So now we proceed into a new chapter of sound design.....Diffusers, from Q.R.D.'s to advanced Quaternary designs, there is a lot to discover in this field of acoustical engineering.

Please be patient, as this information will follow shortly. Thank You.
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Re: The Trouble with Treble, A Space O.D.D.Y.S.Y.
Reply #11 - 09/13/17 at 03:31:35
 
Before we get started with diffusion, I wanted to post this information concerning corner bass traps.

So here is a basic layout of how your corner bass traps should be built. These are full length from floor to ceiling and are built directly into the corner walls. The panel is diaphragmatic, and must be unobstructed in order to operate properly through resonance of frequency. That resonance factor is determined by the thickness, and rigidity of the face panel. High grade plywood is a very good material to use. The panel edges are sealed in place, but are free to vibrate within the mounting channels. Make sure that the fiberglass behind the panel maintains an airspace between the two or the performance will suffer.



Okay, so that should just about cover the subject of absorption control. Now we are ready to begin covering diffusion concepts.

PLANAR BINARY AMPLITUDE DIFFUSION: B.A.D. Panel



Sound is attenuated by absorption, re-directed by reflection, and uniformly dispersed by diffusion. By varying the phase of the scattered waves, we can effectively diffuse the sound waves. The binary amplitude diff-sorber maintains a well controlled combination of absorption and diffusion, using a variable impedance scheme comprised of reflective and absorptive areas. These areas provide pressure reflection coefficients by a factor set of 0 and 1 per a Maximum Length Sequence, or M.L.S. The M.L.S. Is based upon shift register theory, rendering it an ideal candidate for successful implementation.

This will achieve a flat power spectrum using values of easy computation. Most importantly, this technique provides an important and valuable asset to your audio room. Your listening space will take on a vast new sense of spaciousness while maintaining natural ambience. The ambiance of your listening space is delicate, and extremely vulnerable to acoustic influence or interference.

There is a drawback to where the standard B.A.D. panel falls short of optimal performance, and there is a solution. In the upper frequency range, as there becomes a reduction of the binary patch below ½ wavelength in proportion, specular reflection is restricted to an attenuation of approximately 6dB within a surface area that is fifty percent absorptive. This situation is corrected by a new “ternary” sequence which based upon interference, has the ability to reflect waves in an “out-of-phase” condition, which in turn, forms a dramatic reduction upon specular energy.  

This modified sequence is comprised of -1's, 0's, and +1's. The major change here of course is the addition of the final well designed with a depth of ¼ wavelength at the design frequency, the Fo, and odd multiples of this frequency. This “end well” now produces a reflection coefficient of -1 to the incoming wave. Therefore, you now have a well that transforms these waves “out-of-phase” with the primary influence responsible for the specular energy.

This infiltration upon areas R = +1 results into substantial reduction of that specular energy, and better diffusion is the gain. There is even one more advancement that can be initiated to provide even further gain in performance, that being another design approach, the “Quaternary” number theory sequence.  I am not going into that technique any time soon due to complexity. For now, I am satisfied with the advanced ternary sequence in order to get the job done.  But wait!...there's more on where this design can go. I shall touch on this later in this writing.

If your space is large enough to allow full projection of bloom between a diffuser and you, then I would definitely suggest the Quadratic Residue Diffuser approach. It would still be beneficial to take advantage of the diff-sorber binary amplitude concept, just as an auxiliary acoustical treatment along with the higher prime element 1d diffusers, BUT, only when placed to avoid repetitive lobing derived from periodic sequences which causes destructive interference on it's own part. The way to avoid this problem is by using a-periodic placement with properly inserted panels of “inverted” wells. The effective coefficient of the diffusion will increase substantially.


So here is the finished TERNARY design which I expanded in form by the implementation of folding, and inversion to create the higher order sequence.





For the Binary Amplitude Diffuser, the auto-correlation function of the surface reflection is responsible for even dispersion well into the distant domain. For the uni-polar model (standard B.A.D. panel), cancellation within the side lobes are due to the resulting reflection coefficients being either zero or one.

But for this improved ternary design, the factor of optical sequences are justified.  For the improved ternary sequence, the auto-correlation function allows cancellation within the side lobes resulting in optimal total side lobe energy.

Diffuse reflections are those dispersed in space with both spatial and temporal factors intact.  An “ideal” diffuser would be expected to generate the spatial and temporal spread evenly across the entire audio spectrum within the human auditory range.  Ideal sequences are those with strong auto-correlation qualities. Strong auto-correlation properties will result into a flat power spectrum, in turn resolving the scattering cycle consistently throughout with great diffusion as a result.

An important factor to incorporate into the diffusion process is that of A-periodicity. This is achieved by using a long number sequence with good auto-correlation properties. One workable solution is to use a modulation concept. What really works well is to establish an array with the diffuser, and its own inverse, however, these must interchange to form an “A-periodic” formation.

I suggest the use of Binary-Amplitude-Diff-sorbers (B.A.D. Panel) in the curved version to suppress sidewall reflections as an alternative method to simply using panel absorbers. This in basic form started out as a flat hybrid surface utilizing a “zero” depth perforated mask over a porous absorbent material. These panels are diffusive from about 1k on up with a transition to pure absorption below that frequency.

These were developed utilizing the Chinese Remainder Theorem in which to fold one dimensional sequences into two dimensional arrays with preservation of the desirable auto-correlation and Fourier properties responsible for their performance properties.

More recently, this concept found improvement by use of smaller variable size square panels.  I have the pattern and design layout for these panels as well. I will cover this design process further on in this writing.

Through a logical grouping manner, good diffusion remains far less affected by lobing, which normally results from periodic repetition. Through variable placement of various depths of these panels in which to form an a-periodic sequence array, considerable improvement in performance comes into play when grouping a large array of these panels together.  

The “flat” version of the B.A.D. panel Inherently produced specular reflections that were not exactly optimum for a great diffuser. The answer to correcting this problem was through incorporating curvature to the binary encoded perforated panel. This bending of the flat surface resulted in redirection of the binary wells to now operate out-of-phase, therefore drastically reducing the specular reflection, while maintaining the absorption coefficient, but with far greater dispersion patterns. The curved B.A.D. panel enriches the sweet spot for greater spatial interpretation, and overall clarity.

The design of the binary amplitude diff-sorber panel is to achieve diffusion at or near one octave over the frequency for which the wavelength is two times the binary element in surface area. This creates a uniform diffusion pattern which is spread over a wide frequency range.

So additionally, I propose yet another alternative to standard Q.R.D. diffusers. This model is derived from simpler two dimensional sequencing, based on the Binary-Amplitude-Diffuser/Absorber concept.

The design layout as you see in three stages of development here results from folding, and inversion, until a full, high order grid evolves into a very powerful tool for your room acoustics arsenal. This device can work similar to the ternary version, in that you can fine tune your room like you fine tune a speaker's crossover network in order to achieve the sound quality that you desire.

You can easily see the degree of built-in diffusion compared to the amount of absorption built into these panels. The blue segments represent the hard diffusive areas or 1, and the white areas represent absorption or 0.

Now this model is quite a bit different from the Ternary diffusion concept, as the Ternary version is much more complex, and far more difficult to build.  This version is built directly onto the wall with interconnecting panels in a proper sequence which allows it to evolve into the higher order grid.  This grid is built in smaller sections as dictated by the full grid sequence. You start with a .75” plywood backing with multiple layers of semi-rigid 1/2” fiberboard sheathing (Celetex High Density Fiberboard) built up over the plywood. This board material is very dense and fibrous, while still manageable, and much safer for your health to use. Multiple sheets layered with air gaps sealed in-between, create a very good absorption coefficient, while providing an excellent base to build the diffusion segments upon. The reflective segments must be a very hard material, and non-absorbant to the working frequencies of this design.

At the very least, you need hardwood, or a thin metal covering to insure a surface which can't be penetrated. Do NOT use MDF or soft wood, unless you glue a metal face to the segment. You can buy sheet metal to cut this from. Thick HVAC aluminum tape could work on a wood base, but something thicker might be in order. Several coats of hard urethane applied to hardwood should do well by itself. The pieces that make up the segments are all identical and measure .05” square by .05 “ depth (1/2” cubes), glued directly to the top sheet of Celetex fiberboard.

A grid pattern template will be necessary to install the segments in proper and uniform sequence. This will be used repeatedly for quick, easy building of the unit. Your grid is already built for you and waiting to be picked up at the local big box store. You get a ceiling light grid for about $15 which is plastic, and just happens to be a bit over ½ inch by ½ inch square wells, and the perfect depth to work with. These lighting grids are big enough for the design layout of one section which is a 35 x 36 well grid.

If you want to step up the design a notch, I recommend actually using the plastic grid panels permanently as the top layer. You simply cut the wood cubes precisely to fit snugly within the plastic grid wells and if they are snug enough, they won't require glue to keep them in place.  I have already done this technique and it works very well. You need to be absolutely precise and double check the fit of your cubes as you cut them. It sucks to have to throw out a bunch of hardwood cubes that not only are expensive, but you just spent half a day cutting them.  Always use quality control measures as you do batch work. An alternative which is easier, and will guarantee success, is that of pouring liquid plastic into the wells requiring reflection, instead of cutting all of those wood cubes. It is your choice as to what works best for you.

You will make a reusable template with this lighting grid by painting the appropriate absorption wells red, and leaving the diffusive wells white. DO NOT screw up the grid sequence, as the mistake will be repeated over and over again until it becomes a major flaw within the sequence. Take pride in your work, and absolutely double check your layout.

You only have to lay out one section to be used as your production template. This allows easy, and fast placement of the diffusion segments as you glue them in place to the fiberboard underneath. All you have to do is flip the grid and turn it as the full grid sequence dictates. Very simple to do, and allows rapid development of large scale units.

I would suggest screwing the plywood onto your wall directly to the studs which should be 16 inches on center. Secure this panel to your wall well, as it is going to be heavy when finished. Then you can build onto the face of the plywood backing. Since the celetex sheets and the plywood are about the same size, go ahead and mount the material full size to the plywood. Do not mount face to face flush. You will build a wood frame around the perimeter and also a center strip for which the next layer attaches. Do this with every layer. A half inch airspace should suffice between layers.  The last layer of celetex could be mounted to the wall after you glue the diffusive segments on, it is your choice. It is easier to glue these segments in place on a bench. I suggest three layers of celetex total over the plywood, which gives you 3 inches of absorption including the airspace allotted between the layers. The airspace provides a much greater absorption coefficient, therefore do not omit this important factor.

The one modification that I strongly recommend is the addition of a full facia which covers the entire face side of the absorption material (a very thin hard layer), just as with the Ternary Diffuser/Absorbers, Why is that, and what purpose does this serve?

The reason for this is a very logical approach to fine tuning the degree of diffusion and absorption ratios in a controlled manner, by order of frequency transition modeling. The thickness/hardness of the facia becomes the crossover point where you want absorption coefficients to take affect, leaving frequencies above that range untouched and un-absorbed. This prevents over absorption of delicate higher frequencies in order to preserve ambient spatial bloom within the room. At that determined transition point, full absorption begins to take affect to extend well below that point.

More to follow soon, please check back as we continue.
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Re: The Trouble with Treble, A Space O.D.D.Y.S.Y.
Reply #12 - 09/13/17 at 16:37:25
 
So yes, this acts like a solid wall for those frequencies above the transition point of your determination. The absorption ratios of this design are part of what makes this device work. There really can't be diffusion for any frequency above the transition point. Those higher frequencies crossed over from the transition point will simply be reflected back into the room.

You can use a frequency specific QRD (Quadratic-Residue-Diffuser) to correct for those frequencies which are bypassed by this design. You can also alternate sections which some can have the facia, while others work full range without it. That is another way to balance things out.

Now the other option is to simply not use the transitional facia, and simply allow the binary elements to work full scale across the spectrum. This may, or may not exceed the level of absorption needed for your room.  This is simply an optional part of this design which you don't have to use if you don't need it, but it is very handy for fine tailoring of your room acoustics.

Every frequency has a determined point of penetration within a given material. The transition point simply refers to the point of where a certain frequency can either penetrate the barrier as if it didn't even exist, or bounce off it because it can't penetrate that particular barrier. You have to determine the material used for your specific cross-over point. These devices are very good choices for small rooms, and large rooms alike. When the space required for QRD's isn't available, then this is an excellent alternative to use. These are a good option for ceiling grids as well.

So, with that said, I would like to introduce to you my modified version of the Binary Amplitude Diffuser system which is simpler than the Ternary design, but works very well when placed in the proper sequence and order.  These are much easier to build than the more complex Ternary models.

Note: The data used to design this model is based upon the theory and  design developed by D'Antonio, and Cox for RPG Diffuser Systems. Perhaps Angus was in on this development too. If so, please be acknowledged.

These will not perform to the same degree as the superior Ternary version does by comparison, but this is definitely a great choice of diffusion design when you are in a small room with limited space.  And of course, they will work well in larger rooms too.

This is simply a great alternative when you can't use standard Q.R.D.'s. Just in case you don't understand why this is problematic, to put it simply, every Q.R.D. by its inherent design factors will dictate the amount of space needed to travel in time in order to properly execute the diffusion cycle.  Otherwise, you just have an UN-effective device that simply gives you the illusion of actually doing anything for your situation. Please make sure that the acoustic elements which you choose to place within your room are the correct choices. Otherwise, you are just wasting time, money, and effort by not getting what you had bargained for.  Do it right, and you will KNOW that you did it RIGHT!



The initial first stage sequence doesn't visualize very well into the grand scheme of things, but as you see the pattern advance throughout the binary sequencing, you really begin to see the complexity unfold within how this device works in the third stage.  Now you have an art form for your wall that ACTUALLY does something! Imagine that.

Here is the initial template that is all you need to form the rest of this diffusion sequence. This is accomplished through several stages of folding, and inversion.  The data provided, and all images are protected as intellectual property by patent. You are NOT authorized to reproduce any of these designs or the data involved for the purpose of commercial profiting. Please do not attempt to sell these models. This information is provided for personal use ONLY and for educational purposes. You better get permission from D'Antonio for licensing if you intend to do otherwise.

I really hate to bring that disclaimer up, but in today's society, we simply have to. There are way too many jerk-offs out there who are unscrupulous bottom feeders.

Stage ONE....The Template








Stage TWO....Quad folding / inversion sequence





Stage THREE...The Full Binary Sequence






Ternary designs with higher performance using built-in Cross-over-Frequency-Transition


An improvement to the ternary design which maintains high performance diffusion, with controlled absorption at lower frequencies, is that of incorporating a frequency cross-over barrier. The idea is to apply a fascia of a thin hard material which reflects sound above a pre-determined transition frequency of choice, and transmits sound below this frequency to a sound absorbing backing. All frequencies below the transition point, and above 1 kHz will be diffused, while transitioning to full absorption below 1 kHz.  This crossover barrier is optional, with flexible tuning by the user for specific acoustical modeling.

This concept is essentially stopping the absorption factor directly over the absorption R=0 portions of the ternary sequence. The quarter wave R=-1 wells can be left uncovered, as they reflect with minimal absorption anyway. Yes, by design there is inherent absorption using this well depth concept, but not enough for concern as compared to the high absorbent coefficient of the R=0 wells.

So, the actual absorbent within the R=0 wells can be directly coated with a hard material which shall be determined to provide the transition cross-over point where full absorption is required. This is critical in order to preserve the delicate balance of the upper frequencies for which to maintain ambiance, and preserve spatial quality, thus keeping that crystalline sparkle alive!

The thickness of the diffusive fascia is directly correlative of the transition frequency between absorption and diffusion.
The constant is that the thicker the coating for which to create this "cross-over", the lower the transition frequency shifts, leaving the higher frequencies un-absorbed to keep their delicate presence intact. Without this much needed regulated transition, the quality of the music will suffer, and much of its inner detail will be lost. If you want your music to retain sheen and luster to its portrayal, then this critical enhancement must not be overlooked.

It has been determined  that for a fascia 600 microns thick, the transition between absorption and diffusion is at about 250 Hz. 300 microns =500 Hz. A micro perforated fascia @ 150 microns = 1,000 Hz. 100 microns will provide a transition frequency at around 2,000 Hz.

An important disclaimer; This method was patented  in 2016 by the designer Peter D' Antonio of RPG Diffuser Systems, and is proven to be a very effective breakthrough in modern diffuser technology. These designs are intellectual property of RPG Diffuser Systems, and are not authorized for commercial reproduction or distribution. This information is provided simply for educational purposes, and personal use only. In other words, don't be a clown, and think you are going to build these to sell on eBay. There are always consequences for this level of stupidity if you think otherwise.

This advancement has really improved upon not only the early B.A.D. panel design, but that of the much improved ternary version of that concept as well. This new technique simply takes this entire concept to a much higher level of predictable performance standards.

And then comes the further advanced “Quaternary” designs which we will save for another day. Simply put, the Quaternary concept works with a dual-well interference scheme based upon number theory sequences, contributing to the odd and even multiples for a given design frequency, plus it's multiples, resulting in greater, and more uniform diffusion coefficients.

Now comes the really fun part, taming that wicked beast which resides behind your listening position. That fire breathing beast is singeing the hair off of your head, with intense heat caused by all of that low frequency build up, and mass confusion of reflecting sound frequencies, like high pressure fuel feeding the wall of flame...not good, and it really hurts!

And just when you thought is was safe to turn on your stereo
....Oh, sorry about that. This is a fine-tuneable design much like designing a perforated panel absorber. This is a new concept, and I'm sure not many people are aware of it.  I am making you aware of it. You may want to consider its use.  I would obviously recommend these for sidewall treatment as well.

Remember I said it would be nice to add spice to the front wall facing your position?  These transition ternary diffusers are what I had in mind. Simply place a nice tidy array of these directly between the speakers (that is only if you insist on keeping your speakers spread wide apart..that really is not a good thing). Otherwise, these would be good to place in an array above your speakers, and can even be mixed along with some Q.R.D.'s of higher order if the space allows their full efectiveness. Another good area is forward of the bass absorbers, which these diff-sorber units can be placed upon free standing frames for movable portability, and you are really onto something now. OH...and don't forget about your ceiling. These can be mounted into ceiling grids as necessary for total control and should work quite effectively for that purpose. There are a few more important tweaks to fine tune your room, but we covered the major areas which will make the most difference for now.

That's right, get rid of that last part of the destructive equation, and may the force be in your music not your room...okay, back to reality.


Coming up next...An in depth look into Q.R.D. diffusion models and how they just may work for your situation.....
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Re: The Trouble with Treble, A Space O.D.D.Y.S.Y.
Reply #13 - 09/14/17 at 15:59:33
 
Paul, thank you for taking the time and effort to convey all this info. It will take some time to absorb. And so my room continues WIP !
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Re: The Trouble with Treble, A Space O.D.D.Y.S.Y.
Reply #14 - 09/15/17 at 17:11:28
 
This is like 18 year of my proselytizing on room treatment crammed into one thread. Well done!!

I think very few here are up to the challenge though, and I often hear - but my wife....

I also get the spiel about how they don't want an anechoic chamber...which means either they weren't listening or I'm not explaining things well enough.

What's your thoughts on Fractal (nested) QRD?

Here is a photo of my QRD-29 (similar to your 23 builds) that was a PITA to build, and I'm unhappy with how the fins flex. And my nested QRD that I built to be shown at Axpona this year.



We should chat about the technicalities of building these. I've been day dreaming about a plan to build a big QRD 17 or 19 fractal for my rear wall of my main listening room where I have about 9 feet to my seating position. I want it to go as deep as possible, but still be broadband, so I'm thinking QRD 19, about 16" deep, with QRD 7s nested in the wells. Since it's going to be hung on the walls, I'd probably have it broken into multiple smaller sections to form the whole, and 2 Periods total. That would also make it easier to rout the nested QRD 7s if I made a bunch of 24" pieces rather than tried to rout 48" or 60" long pieces (depending on how tall I feel like going).

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Re: The Trouble with Treble, A Space O.D.D.Y.S.Y.
Reply #15 - 09/16/17 at 14:05:29
 
So if I do this stuff will it make the music streamed from my phone into my Lepai amplifier sound better? Or should I wait until I can afford some Amazon Echo Dot's?
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Re: The Trouble with Treble, A Space O.D.D.Y.S.Y.
Reply #16 - 09/16/17 at 14:44:41
 
Paul,

Thanks for the information. I am a big believer in room treatment (if you can do it),  amazing how helpful it was in my case. In my living room most people believe my diffusers are artwork and don't realize they not only look good but are functional.
Raven nice work on those diffusers.

JD
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Re: The Trouble with Treble, A Space O.D.D.Y.S.Y.
Reply #17 - 09/16/17 at 18:15:42
 
RFZ_Quest wrote on 09/16/17 at 15:46:02:
It is a good thing that at least someone like Lonely Raven is still around to shed some light on the subject.  Too bad that this forum has been reduced to the likes of downloading image after image of someone's record collection. Oh...and all that great info about music downloads which every real audiophile should be listening to.   There used to be some really well informed people on this forum, who actually opened up doors of challenging subjects. Subjects which actually made people think and take on new ideas and concepts.   Where has all of that gone?  I know many of them are current members of other forums. You have to wonder why that is??   Some of you are still around, but this is beginning to be about as active as Detroit.

Sorry it seems to bother you but for me the beauty of Decware products and audiophila in general is listening to music. I don't have the space to have a dedicated listening room and enjoy listening to music in my living area. Room treatment is fine but really unnecessary for me to enjoy the music in excellent sound, and I enjoy seeing the music that others are enjoying with their equipment. I'm in it not for sound staging and the very best sounding stuff but for the enjoyment of all kinds of music. There's room for all of us here, the tech heads and the music lovers and the room treaters.
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Re: The Trouble with Treble, A Space O.D.D.Y.S.Y.
Reply #18 - 09/16/17 at 18:42:15
 
I'm going to second Lon's sentiments and also say that there are plenty of "my way or the hi-way" forums you can move to.
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Re: The Trouble with Treble, A Space O.D.D.Y.S.Y.
Reply #19 - 09/16/17 at 19:56:06
 
I think it's great to share information and I love seeing what people are listening too. I've learned a lot on this forum. Lot of good people.

JD
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mark58
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Re: The Trouble with Treble, A Space O.D.D.Y.S.Y.
Reply #20 - 09/16/17 at 20:14:12
 
I guess I should post this over here so what's his face sees it.  If someone doesn't like to see what we listen to, I suggest they pass on by...don't bother stopping in on our friendly thread but they definitely shouldn't be wasting OUR time whining about it.      ;D  
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« Last Edit: 09/16/17 at 20:14:33 by mark58 »  

"The man that hath no music in himself, nor is not moved with the concord of sweet sounds, is fit for treasons, deceptions, and spoils;
The motions of his spirit are dull as night and his affections dark as Hell. Let no such man be trusted." William Shakespeare
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Donnie
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Re: The Trouble with Treble, A Space O.D.D.Y.S.Y.
Reply #21 - 09/16/17 at 20:21:51
 
Wow, that got ugly quick.
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mark58
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Re: The Trouble with Treble, A Space O.D.D.Y.S.Y.
Reply #22 - 09/16/17 at 20:38:09
 
Donnie, No uglier than some of your projects....HAHAHA
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"The man that hath no music in himself, nor is not moved with the concord of sweet sounds, is fit for treasons, deceptions, and spoils;
The motions of his spirit are dull as night and his affections dark as Hell. Let no such man be trusted." William Shakespeare
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Donnie
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Re: The Trouble with Treble, A Space O.D.D.Y.S.Y.
Reply #23 - 09/16/17 at 21:11:00
 
Mark58, I'll drink to that!
Most of my projects are more than a little sketchy!
I will say that I noticed that things have slowed down a bit around here after getting back from my misspent summer.
I like both the tech stuff and what everyone is listening to.
I just like music.
Right now I am listening to music from my main system with my Torii out of the chain and replaced with a $25 Lepai. It is a crazy world that I live in
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mark58
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Re: The Trouble with Treble, A Space O.D.D.Y.S.Y.
Reply #24 - 09/16/17 at 21:25:39
 
Donnie, "The Red Torii" broken?  Say it isn't so!  A nice Torii MK III just sold for $1850 plus shipping...or at least that was the asking price.  I must admit I was more into the tech stuff when I had issues to solve, now I mainly listen to Music, roll and buy tubes  and buy LPs & CDs.  It's all good and there's a place for all of us obsessed by some aspect of this Hobby.  Mark.
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"The man that hath no music in himself, nor is not moved with the concord of sweet sounds, is fit for treasons, deceptions, and spoils;
The motions of his spirit are dull as night and his affections dark as Hell. Let no such man be trusted." William Shakespeare
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Jeff of Arabica
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Re: The Trouble with Treble, A Space O.D.D.Y.S.Y.
Reply #25 - 09/17/17 at 08:11:16
 
Paul,
I really appreciate the time and effort you put into crafting this series of posts on room treatments.  As someone who is intensely interested in this topic, I was moved.  You know your stuff and it is clearly evident in what you have posted these last few days.  This is a topic that demands research, scientific process, and most importantly...  commitment.  You can check all those boxes.  

I am fairly certain that your intent here was noble.  But your "bedside manner" really sucks!!  As one who is admittedly interested in this topic - and more specifically your posts - I found it dreadfully painful reading through all that you have written.  I simply wanted to learn more about room acoustics but as much as I gained from your intellectual input on this subject matter, I was put off by the unnecessary, presumptuous, polarizing banter that plagued every one of your posts.  I hate to say this, because you have obviously put so much effort into creating the content of your posts, but I am having a difficult time respecting your commentary as an expert in this field due to the fact that you have successfully alienated a great percentage of members on this forum - many of which don't fit the prejudicial mold you have so willingly spewed in this forum.  

My advice to you is this.  If your goal is to get more people to respect and adopt the principles of room treatments that you have shared, stop with the insults and belittlement.  If you think that a "brute force" approach to persuasion is fitting in this forum of members - many of whom have long preceded your presence here -  you are misguided.  Be a steward, not a douche bag.

Personally, I want to learn more from you and others here - like Lonely Raven.  I have enjoyed only the elements of your posts that relate to the technical advice, and I encourage you to continue on with imparting your knowledge in a respectful and PROFESSIONAL manner.  Peace out....
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Re: The Trouble with Treble, A Space O.D.D.Y.S.Y.
Reply #26 - 09/18/17 at 20:41:23
 
..........Our listening rooms are, in fact, the largest component we own. Having said that, I long for the day that I could have back one of the listening environments of my past. Only once did I own a home that music sounded really good without needing n acoustic treatment, at least for the level of loudness that I was using to listen to my music.
 I now live in a small home where the listening room is not good, and the addition of wood flooring made it worse. Maybe it is because of this that I love my headphones so much these days... thanks so much Jeff for the great deal on my ZMF Ori phones.
 To get back to a place where I could make the sound more realistic, if you will, or amenable to this room, I will have to take some sort of plunge into correction. It really is about physics here, and fortunately for some of us like Lon, the listening room isn't completely poisoned. Mine however, is dreadful, and will benefit from some form of treatment.
 Perhaps the previous posts were long winded for me, yet, I must admit that they were helpful as to how I might proceed.
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Re: The Trouble with Treble, A Space O.D.D.Y.S.Y.
Reply #27 - 09/20/17 at 15:23:20
 

I used to wonder why so many people stuck to headphones so staunchly, then a post like above reminds me that headphones remove the biggest problem in a speaker setup...the room!  And I get it.

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Re: The Trouble with Treble, A Space O.D.D.Y.S.Y.
Reply #28 - 09/20/17 at 16:48:00
 
LR, you make a good point.  One reason why I don't sweat my room is that I much prefer my speakers to my headphones.  (My room is very complex which would make treatment impossible for me in any case.)
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Re: The Trouble with Treble, A Space O.D.D.Y.S.Y.
Reply #29 - 09/20/17 at 18:51:18
 
 Ironically, I have heard many teaks to headphones for best bass, best treble, etc using *better* Earpads, or little pieces of foam stuck into the earcup, and of course, the almighty headphone cable debate.
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Decware 34I.3 integrated amp/Forte' 3 bass amp/Velodyne SMS-1 bass mngmnt system/Decware ZOB speakers/BESL subs/Emotiva ERC3 CD player/BPT 3.0 power cond. PS Audio P500
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