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Current listening_evaluation room acoustics (Read 17289 times)
RFZ_Quest
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Current listening_evaluation room acoustics
11/11/08 at 14:21:21
 
The current view from my listening position, as this great experiment in acoustical control advances.



Unlocking the secrets of premium sound one step at a time.
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RFZ_Quest
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Re: Current listening_evaluation room acoustics
Reply #1 - 11/11/08 at 14:23:41
 
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RFZ_Quest
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Re: Current listening_evaluation room acoustics
Reply #2 - 11/11/08 at 14:28:03
 


left side of room with basic prime 13 diffusers.
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RFZ_Quest
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Re: Current listening_evaluation room acoustics
Reply #3 - 11/11/08 at 14:29:59
 


Left side of room full view with absorber unit above fireplace.
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RFZ_Quest
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Re: Current listening_evaluation room acoustics
Reply #4 - 11/11/08 at 14:33:13
 


The right side of the room with broadband absorbtion units mounted on the wall.
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RFZ_Quest
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Re: Current listening_evaluation room acoustics
Reply #5 - 11/11/08 at 14:48:57
 
The back wall directly behind my listening position..


My latest design and build. This is a Quad grouping of single sequence Prime 23-Hybred-Diffusion/Absorption modules. The platform they rest on is built airtight from 3/4 MDF and sectionalized.

These units are designed at full broadband specifications for maximum performance, with a depth of 18 inches @ a well width of .5 in a two dimensional pattern.

These units are extremely heavy and had to be assembled in position due to the weight. With the bass trap platform plus the four units, I estimate the weight to be somewhere around 800+ pounds!

All wells are filled with Celetex absorption panels to fill the cavities behind each well depth.

Attention to detail focuses upon the reduction of 'lobing' which is a result of repetitive sequences. This is corrected by reducing the "ZERO" or end wells to one-half of the specified well width used in the diffuser design.
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RFZ_Quest
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Re: Current listening_evaluation room acoustics
Reply #6 - 11/11/08 at 14:51:19
 
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RFZ_Quest
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Re: Current listening_evaluation room acoustics
Reply #7 - 11/11/08 at 14:55:08
 


Close up view of prime 23 'single-sequence'.
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RFZ_Quest
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Re: Current listening_evaluation room acoustics
Reply #8 - 11/11/08 at 15:02:26
 


D.I.Y. radius design 'Binary-Residue-Remainder' diffusion modules with semi-rigid absorption material mounted directly to the panel rear. These have an internal airspace with a backplate of airtight Celetex.

These are the big guns when it comes to diffusion control.
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Steve Deckert
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Re: Current listening_evaluation room acoustics
Reply #9 - 11/12/08 at 02:09:19
 
RFZ_Quest,

Nice pics and job well done!!!  I wish everyone would go to so much trouble... the world would literally be a better sounding place!  Oh sure, the wife factor, but then 50% of us statistically will get divorced from our first marriage so that gives 1/2 of all men a fair chance at room treatment.  ;)

I'm fascinated by the diffuser you built on your back wall...  I crunched some numbers using the same math that created our diffusers to see what it would take to have an 18 inch well depth with 1/2" spacing and came up with the following single diffuser:
This is a single unit 72 inches wide and 72 inches high.

Well Number 0   WellDepth = 0 inches          Proportionality Factor = 0
Well Number 1   WellDepth = 0.1313869 inches  Proportionality Factor = 1
Well Number 2   WellDepth = 0.5255474 inches  Proportionality Factor = 4
Well Number 3   WellDepth = 1.182482 inches   Proportionality Factor = 9
Well Number 4   WellDepth = 2.10219 inches    Proportionality Factor = 16
Well Number 5   WellDepth = 3.284672 inches   Proportionality Factor = 25
Well Number 6   WellDepth = 4.729927 inches   Proportionality Factor = 36
Well Number 7   WellDepth = 6.437956 inches   Proportionality Factor = 49
Well Number 8   WellDepth = 8.408759 inches   Proportionality Factor = 64
Well Number 9   WellDepth = 10.64234 inches   Proportionality Factor = 81
Well Number 10   WellDepth = 13.13869 inches  Proportionality Factor = 100
Well Number 11   WellDepth = 15.89781 inches  Proportionality Factor = 121
Well Number 12   WellDepth = 0.6569343 inches Proportionality Factor = 5
Well Number 13   WellDepth = 3.941606 inches  Proportionality Factor = 30
Well Number 14   WellDepth = 7.489051 inches  Proportionality Factor = 57
Well Number 15   WellDepth = 11.29927 inches  Proportionality Factor = 86
Well Number 16   WellDepth = 15.37226 inches  Proportionality Factor = 117
Well Number 17   WellDepth = 1.445256 inches  Proportionality Factor = 11
Well Number 18   WellDepth = 6.043796 inches  Proportionality Factor = 46
Well Number 19   WellDepth = 10.90511 inches  Proportionality Factor = 83
Well Number 20   WellDepth = 16.0292 inches   Proportionality Factor = 122
Well Number 21   WellDepth = 3.153285 inches  Proportionality Factor = 24
Well Number 22   WellDepth = 8.80292 inches   Proportionality Factor = 67
Well Number 23   WellDepth = 14.71533 inches  Proportionality Factor = 112
Well Number 24   WellDepth = 2.627737 inches  Proportionality Factor = 20
Well Number 25   WellDepth = 9.065694 inches  Proportionality Factor = 69
Well Number 26   WellDepth = 15.76642 inches  Proportionality Factor = 120
Well Number 27   WellDepth = 4.467154 inches  Proportionality Factor = 34
Well Number 28   WellDepth = 11.69343 inches  Proportionality Factor = 89
Well Number 29   WellDepth = 0.9197081 inches Proportionality Factor = 7
Well Number 30   WellDepth = 8.671533 inches  Proportionality Factor = 66
Well Number 31   WellDepth = 16.68613 inches  Proportionality Factor = 127
Well Number 32   WellDepth = 6.70073 inches   Proportionality Factor = 51
Well Number 33   WellDepth = 15.24088 inches  Proportionality Factor = 116
Well Number 34   WellDepth = 5.781022 inches  Proportionality Factor = 44
Well Number 35   WellDepth = 14.84672 inches  Proportionality Factor = 113
Well Number 36   WellDepth = 5.912409 inches  Proportionality Factor = 45
Well Number 37   WellDepth = 15.50365 inches  Proportionality Factor = 118
Well Number 38   WellDepth = 7.094891 inches  Proportionality Factor = 54
Well Number 39   WellDepth = 17.21168 inches  Proportionality Factor = 131
Well Number 40   WellDepth = 9.328467 inches  Proportionality Factor = 71
Well Number 41   WellDepth = 1.708029 inches  Proportionality Factor = 13
Well Number 42   WellDepth = 12.61314 inches  Proportionality Factor = 96
Well Number 43   WellDepth = 5.518249 inches  Proportionality Factor = 42
Well Number 44   WellDepth = 16.94891 inches  Proportionality Factor = 129
Well Number 45   WellDepth = 10.37956 inches  Proportionality Factor = 79
Well Number 46   WellDepth = 4.072993 inches  Proportionality Factor = 31
Well Number 47   WellDepth = 16.29197 inches  Proportionality Factor = 124
Well Number 48   WellDepth = 10.51095 inches  Proportionality Factor = 80
Well Number 49   WellDepth = 4.992701 inches  Proportionality Factor = 38
Well Number 50   WellDepth = 18 inches        Proportionality Factor = 137
Well Number 51   WellDepth = 13.0073 inches   Proportionality Factor = 99
Well Number 52   WellDepth = 8.277372 inches  Proportionality Factor = 63
Well Number 53   WellDepth = 3.810219 inches  Proportionality Factor = 29
Well Number 54   WellDepth = 17.86861 inches  Proportionality Factor = 136
Well Number 55   WellDepth = 13.92701 inches  Proportionality Factor = 106
Well Number 56   WellDepth = 10.24818 inches  Proportionality Factor = 78
Well Number 57   WellDepth = 6.832117 inches  Proportionality Factor = 52
Well Number 58   WellDepth = 3.678832 inches  Proportionality Factor = 28
Well Number 59   WellDepth = 0.7883212 inches Proportionality Factor = 6
Well Number 60   WellDepth = 16.42336 inches  Proportionality Factor = 125
Well Number 61   WellDepth = 14.05839 inches  Proportionality Factor = 107
Well Number 62   WellDepth = 11.95621 inches  Proportionality Factor = 91
Well Number 63   WellDepth = 10.11679 inches  Proportionality Factor = 77
Well Number 64   WellDepth = 8.540146 inches  Proportionality Factor = 65
Well Number 65   WellDepth = 7.226277 inches  Proportionality Factor = 55
Well Number 66   WellDepth = 6.175182 inches  Proportionality Factor = 47
Well Number 67   WellDepth = 5.386861 inches  Proportionality Factor = 41
Well Number 68   WellDepth = 4.861314 inches  Proportionality Factor = 37
Well Number 69   WellDepth = 4.59854 inches   Proportionality Factor = 35
Well Number 70   WellDepth = 4.59854 inches   Proportionality Factor = 35
Well Number 71   WellDepth = 4.861314 inches  Proportionality Factor = 37
Well Number 72   WellDepth = 5.386861 inches  Proportionality Factor = 41
Well Number 73   WellDepth = 6.175182 inches  Proportionality Factor = 47
Well Number 74   WellDepth = 7.226277 inches  Proportionality Factor = 55
Well Number 75   WellDepth = 8.540146 inches  Proportionality Factor = 65
Well Number 76   WellDepth = 10.11679 inches  Proportionality Factor = 77
Well Number 77   WellDepth = 11.95621 inches  Proportionality Factor = 91
Well Number 78   WellDepth = 14.05839 inches  Proportionality Factor = 107
Well Number 79   WellDepth = 16.42336 inches  Proportionality Factor = 125
Well Number 80   WellDepth = 0.7883212 inches Proportionality Factor = 6
Well Number 81   WellDepth = 3.678832 inches  Proportionality Factor = 28
Well Number 82   WellDepth = 6.832117 inches  Proportionality Factor = 52
Well Number 83   WellDepth = 10.24818 inches  Proportionality Factor = 78
Well Number 84   WellDepth = 13.92701 inches  Proportionality Factor = 106
Well Number 85   WellDepth = 17.86861 inches  Proportionality Factor = 136
Well Number 86   WellDepth = 3.810219 inches  Proportionality Factor = 29
Well Number 87   WellDepth = 8.277372 inches  Proportionality Factor = 63
Well Number 88   WellDepth = 13.0073 inches   Proportionality Factor = 99
Well Number 89   WellDepth = 18 inches        Proportionality Factor = 137
Well Number 90   WellDepth = 4.992701 inches  Proportionality Factor = 38
Well Number 91   WellDepth = 10.51095 inches  Proportionality Factor = 80
Well Number 92   WellDepth = 16.29197 inches  Proportionality Factor = 124
Well Number 93   WellDepth = 4.072993 inches  Proportionality Factor = 31
Well Number 94   WellDepth = 10.37956 inches  Proportionality Factor = 79
Well Number 95   WellDepth = 16.94891 inches  Proportionality Factor = 129
Well Number 96   WellDepth = 5.518249 inches  Proportionality Factor = 42
Well Number 97   WellDepth = 12.61314 inches  Proportionality Factor = 96
Well Number 98   WellDepth = 1.708029 inches  Proportionality Factor = 13
Well Number 99   WellDepth = 9.328467 inches  Proportionality Factor = 71
Well Number 100   WellDepth = 17.21168 inches  Proportionality Factor = 131
Well Number 101   WellDepth = 7.094891 inches  Proportionality Factor = 54
Well Number 102   WellDepth = 15.50365 inches  Proportionality Factor = 118
Well Number 103   WellDepth = 5.912409 inches  Proportionality Factor = 45
Well Number 104   WellDepth = 14.84672 inches  Proportionality Factor = 113
Well Number 105   WellDepth = 5.781022 inches  Proportionality Factor = 44
Well Number 106   WellDepth = 15.24088 inches  Proportionality Factor = 116
Well Number 107   WellDepth = 6.70073 inches   Proportionality Factor = 51
Well Number 108   WellDepth = 16.68613 inches  Proportionality Factor = 127
Well Number 109   WellDepth = 8.671533 inches  Proportionality Factor = 66
Well Number 110   WellDepth = 0.9197081 inches Proportionality Factor = 7
Well Number 111   WellDepth = 11.69343 inches  Proportionality Factor = 89
Well Number 112   WellDepth = 4.467154 inches  Proportionality Factor = 34
Well Number 113   WellDepth = 15.76642 inches  Proportionality Factor = 120
Well Number 114   WellDepth = 9.065694 inches  Proportionality Factor = 69
Well Number 115   WellDepth = 2.627737 inches  Proportionality Factor = 20
Well Number 116   WellDepth = 14.71533 inches  Proportionality Factor = 112
Well Number 117   WellDepth = 8.80292 inches   Proportionality Factor = 67
Well Number 118   WellDepth = 3.153285 inches  Proportionality Factor = 24
Well Number 119   WellDepth = 16.0292 inches   Proportionality Factor = 122
Well Number 120   WellDepth = 10.90511 inches  Proportionality Factor = 83
Well Number 121   WellDepth = 6.043796 inches  Proportionality Factor = 46
Well Number 122   WellDepth = 1.445256 inches  Proportionality Factor = 11
Well Number 123   WellDepth = 15.37226 inches  Proportionality Factor = 117
Well Number 124   WellDepth = 11.29927 inches  Proportionality Factor = 86
Well Number 125   WellDepth = 7.489051 inches  Proportionality Factor = 57
Well Number 126   WellDepth = 3.941606 inches  Proportionality Factor = 30
Well Number 127   WellDepth = 0.6569343 inches Proportionality Factor = 5
Well Number 128   WellDepth = 15.89781 inches  Proportionality Factor = 121
Well Number 129   WellDepth = 13.13869 inches  Proportionality Factor = 100
Well Number 130   WellDepth = 10.64234 inches  Proportionality Factor = 81
Well Number 131   WellDepth = 8.408759 inches  Proportionality Factor = 64
Well Number 132   WellDepth = 6.437956 inches  Proportionality Factor = 49
Well Number 133   WellDepth = 4.729927 inches  Proportionality Factor = 36
Well Number 134   WellDepth = 3.284672 inches  Proportionality Factor = 25
Well Number 135   WellDepth = 2.10219 inches   Proportionality Factor = 16
Well Number 136   WellDepth = 1.182482 inches  Proportionality Factor = 9
Well Number 137   WellDepth = 0.5255474 inches Proportionality Factor = 4
Well Number 138   WellDepth = 0.1313869 inches Proportionality Factor = 1
Well Number 139   WellDepth = 0 inches         Proportionality Factor = 0

Diffuser Depth = 18 inches
Diffuser Width (= Height) = 72 inches
Well Width = 0.5 inches

Thought you might find it interesting and someone wanting to build a unit this size now has the dimensions without having to do the math!

Steve
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« Last Edit: 11/12/08 at 02:12:58 by Steve Deckert »  
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RFZ_Quest
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Re: Current listening_evaluation room acoustics
Reply #10 - 11/12/08 at 18:59:32
 
Thanks Steve.

I do find this concept to be quite interesting and very feasible concerning construction. †I will most likely build this unit just to put it to test and see how it compares. I have also just finished the plans for a large single-sequence prime-19 module with a 2.25 inch well width @ a maximum depth of 4.5". †These are reduced to the smallest size possible with as wide of coverage as possible to maintain reasonable weight and cost factors. I am planning to build four of these units in the near future but I may try your idea first and then build the p19 units at a later time.

If I were to design a unit based on your figures for commercial resale, it would require a prefab-sectioned concept where the unit is divided into manageable sections and easily rejoined at the consumer end with basic hand tools.

A total kit form where all parts are cut to spec, ready for assembly, †packaged into parts groups, could also be possible for those who are willing to pay the shipping cost and do not want the hassle of building something on this level themselves. The sections could be un-boxed and re-joined together quickly and effortlessly with very little difficulty.

My current set-up is experimental at the moment. However, this type of arrangement has proven to excel dramatically over any other approach for which I've experienced.

The digital diffusers which have a poly-face radius to them, perform incredibly well with a very noticeable difference. The combination absorption factors built into these units is a major aspect which covers the majority of required room absorption without directly contributing to any over-reduction of the frequency balance. There is 3 inches of semi-rigid material with a 5 pound density rating used in each of these units.

There are just short of ten 4 x 8 ft sheets of Celetex used within the prime 23 modules alone! This should give some idea as to the absorption coefficients that are obtained throughout the room. †The additional units mounted on the wall simply rounded everything into perspective concerning frequency balance.

I am currently experiencing the widest, deepest sound-stage that I've heard to date, without the use of external electronics or complicated software programs to produce this type of phantom imaging.

The ambiance reveals a very special quality to it that is difficult to describe and must be experienced to fully understand just what a dramatic improvement this has made. I am hearing a new level of depth into the music with detail that has escaped me in the past. This all by using identical equipment and sound media, so the only real change here is the actual listening elements.

If anyone needs positive proof of what diffusion does for your listening experience, I feel quite confident that this type of approach will easily provide confirmation with a radical departure from the ordinary. I am sure about one thing, music will never be the same without it.
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Steve Deckert
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Re: Current listening_evaluation room acoustics
Reply #11 - 11/13/08 at 01:48:11
 
It's not my idea, nor my math...  just simple quadratic formula as far as I know.  By my calculator, the sequence I listed is the only way it calculates correctly to achieve a 1/2 inch well spacing with an 18 inch depth.   FWIW, that is the frustrating part of quadratic residue diffusers, in that you can't decide you want a unit of a given size to handle a given band of frequencies.  You can decide how low you want it to work, how high you want it to work, or how big you want the face of the unit to be (width=height), but only two of the three.  

For example, the 72 inch unit I listed diffuses frequencies between 187Hz and 18000Hz.  It has an 18 inch well depth with 1/2 inch spacing.

If I decided to make the unit 48 inches then the well depth changes to 12 inches and the unit diffuses between 281Hz and 18000Hz.

If I decided to make the spacing 1 inch instead of 1/2 inch then the high frequency drops to 9000Hz.

Now suppose I am happy with 9000Hz but I would like it to go lower than 281Hz so I decide to change the well depth from 12 inches back to 18 inches.   The math crashes and burns instantly.  The only way I can get it to work is to increase the unit size from 48 inches back to 72 inches.

Of course you have to wonder what would happen if you did it anyway.  My guess is that the well depth compared to the sequence would create a sporadic result where rather than creating an evenly spaced hemi-disk of reflection across all frequencies, you would be creating multiple sub sequences with some frequencies actually amplified and others actually absorbed or muted. (not to mention the rather wild lobing that would likely take place) Nevertheless, if you had enough units covering a large space and you were perhaps twice as far away, like in a concert hall, this could still work.

I have figured out over time that the idea that a quadratic residue diffuser does not create a smooth hemi-disk until you're a great distance away from it, such as 10 or 20 feet is true.  Closer than that and the benefit is mostly from scattering reflections rather than diffusion.  

The direction I have been working in over the past year, of which you have one of the prototypes I believe, is near field treatments that would do a superior job of scattering vs. QRD at distances of 12 inches on out so that audiophiles could use them in smallish listening spaces like those found in most homes.

This unit would probably already be in production if it weren't so time consuming to build, but here is a couple illustrations I did:



In these illustrations I used light to represent a sound source, such as a loudspeaker.  This one shows the unit on a wall about 10 feet away from the sound source that is just below the unit.  The light and shadow shows me what parts of the unit will be reflecting sound from any given angle of incidence.



This one shows what happens when the sound source is nearly point blank minus about 5 degrees vertical.  Can you see the sphere effect?  This is what impresses me most about this design, and proudly I can claim this as my own sequence.  I'm looking forward to measuring it with the mics some day.  I say some day, because I'll have to make another one before I can do it.  The prototype I gave to you and Ziggy  has the very top (or bottom) row botched.  When you're as dyslexic as I am it's a lot harder to glue all these tubes in without making a mistake than you might think!

Anyway, I thought it wouldn't hurt to get a little discussion going about room acoustics in this forum because the average audiophile simply isn't going to give room treatment enough weight in his or her overall system design unless it begins to receive equal billing with all the other forum topics.

Steve  ::)
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RFZ_Quest
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Re: Current listening_evaluation room acoustics
Reply #12 - 11/13/08 at 20:52:03
 
Steve,

There is always going to be some sort of compromise when it comes to design and set-up for something like this. Unfortunately, without an anechoic chamber and the proper gear to run accurate test analysis for these changes, we can at best, use math to give us a predetermined †idea within a certain degree of the performance curve.

It just becomes a trial and error scenario from that point where careful listening evaluations will be the best form of analysis. I think we have always found that what we actually hear is what really matters anyway, over that obtained from test equipment.

The nice thing about the equipment is that actual data can be produced with relative accuracy, showing what the unit actually does rather than just estimating a value based on the numbers. If the units conform to known values, then we can also maintain a predictable value for it's overall performance.

I will stand behind the following. The only thing that matters in the end is how the changes are audibly perceived. I think that it is fair to say that any type of diffusion is better than none at all, although there can and most likely will be a radical difference in how they respond by their design.

I would say that if a unit of 72 inch square size can effectively cover a range that wide, which I know the math predicts this, then it is covering the vast majority of critical frequencies to the extent of where it makes the most difference anyway. A couple of these units placed strategically within the room along with adequate absorption, would most definitely transform the rooms response to a much more favorable quality factor.

This would be like 'doubling' the surrounding space which is perceived audibly by the listener. It would also be like having a major upgrade to the audio system itself. The one thing that I think is overlooked by most people, therefore reducing the relevance of diffusion properties, is the overall value that this provides to the total systems worth in general.

I know how in-depth your experience runs with room acoustics, so I know that you can easily predict what my results are.

For the typical person who has never experienced acoustical correction and the rewarding results obtained from it (most people), it is very difficult for them to formulate in their mind what this really does and how important it actually is to the quality of music.

Until they physically experience the radical transformation that takes place, the power of diffusion will most likely never be understood for it's value and passed off as an afterthought. It is their misfortune †to do so. I can only hope that one day, the light of knowledge will convince these people to focus on this aspect with utmost priority.

One thing to think about. I have a great deal of experience with the equipment and source material in my system, along with many various room set-ups of various acoustical measurements. The one constant that remains, is that every room with it's own set of parameters, is unique in overall response and quality factors. †It is probable that no two rooms will ever sound remotely alike, even when all equipment, set up parameters, and source material remains constant.

It is safe to predict that every owner of a particular amplifier for instance, will have a unique experience and perspective from one owner's room to another. I doubt that any two listeners have heard the sound of that amplifier exactly the same, no more likely than sharing similarities of their fingerprints. To make that possible, both would have to listen in the same room for one to understand exactly what the other hears.

Through the art of acoustical design, it is very possible to alter any room for which to custom tailor the sound to taste, or to present a better chance of cloning another room's sound quality. †

Without corrective measures, the sound is only ever going to be as good as the room allows. In most cases, unless the room was built specifically for optimum acoustical properties, the pending sound quality will cripple the sound of music. What this means is that one will never know the true potential of their gear or how good the speakers actually are, until conditions are right to expose this.

Why would one bother to upgrade his equipment when the most critical factor has been overlooked for lack of it's significance within the listeners mind?

In this case, it is the unseen fiber for which the threads of a musical canvas can be sewn. The key ingredient to quality sound is that of diffusion with absorption supplementing it's overall effectiveness.

I've proven this to myself many times over and always with favorable results. I simply would not listen to my system
without these treatments in place. I have before and it wasn't a pleasant experience. The better option was to just box the equipment back up with the realization that any attempt to hearing a quality musical experience was simply futile without proper room treatments.

Most every problem that I've had with sound quality was generally corrected with acoustical treatments of some sort.

It all comes down to this; don't bother upgrading a system until that system has been truly exposed for it's current quality. †I would bet that the typical system has rarely been heard for it's real capability and quality factor, simply because the room conditions have prevented it.

One would be surprised as to how much upgrade value there really is lurking within the present system without having to replace or alter what is already in place concerning the equipment. Again, the answer lies within the room's condition with far more relevance than the system itself.

Now, as far as the prototype diffusion principal is concerned, I have put some thought into this from a production standpoint. I had to wrap my mind around the design layout and try to predict what was possible from this particular outcome. †

As I viewed it's form, the closest formula that I could relate to it was that of an inverted prime 13 sequence with some sort of variable offsets at the outer well placement. This confused my reasoning to make sense of this form, so I put it off for now.

I am now visualizing the possibility of what can be predicted from this innovative concept in diffusion.

I have in my mind, an alternate method for constructing this module which should provide the same degree of effect, which means that dealing with a bunch of staggered tube placement does not necessarily have to be used to pull it off.

I do not think that a open forum is appropriate for discussing possible trade secrets on something under development here, so I will not disclose any more information here concerning this design.

I will say that my take on this would be of hybrid design which takes full advantage of absorption as the principal behind the diffusion coefficients. I could be wrong about this idea, but then again, I have not had a chance to put any real effort into it.

Please get a hold of me at the shop or PM my box and we can discuss this. †I just have not had the time to do anything with it yet as the new speaker projects are of the highest concern at this point.

If you would like all the parts cut to spec for your other 72" concept and sent to you for assembly at your end so that you may personally evaluate it's performance, I will calculate the material needed and the cost for that material.

As you can imagine, there will be a considerable amount of labor hours involved in creating these kit parts plus packaging them up for shipment. The parts would have to be shipped in several boxes due to weight and size, so this would be fairly costly to ship.

I will provide the labor for free to do this on this one unit, but I would need an advance payment for the material. Shipping cost would also be your responsibility.

If you are not interested, that's fine. Just thought I'd make the offer in case a unit like this has peaked your curiosity for development.

In the mean time, I will continue to keep your new concept on mind as I have not forgotten about it.

Paul.

BTW: this offer only extends to Steve in case anyone else was wondering.
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Re: Current listening_evaluation room acoustics
Reply #13 - 11/13/08 at 23:20:55
 
Then we should not be reading this?
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Re: Current listening_evaluation room acoustics
Reply #14 - 11/14/08 at 07:50:12
 
Maybe we should not be reading this but the concept at this point is quite interesting to me and I will reread this to see what I can understand about doing the same thing for my room. Steve's math is really helpful and I am a professional woodworker so maybe......... I am glad I read it. Thanks Paul and Steve for further enlightenment on the room treatment issue. 18 sheets eh.........
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Re: Current listening_evaluation room acoustics
Reply #15 - 11/14/08 at 13:43:13
 
Hey Guy's,

Thanks for taking interest and for the replies. Please don't take my statement in that manner, as the information posted so far was meant to peak your interest so that more people would put a bit more thought into the relevance of room acoustics.

You know, it has nothing to do with mistrust for the loyal forum members that read this, so again, it was not meant in that manner.

We just have to be careful about certain information so that the ideas are not stolen and someone else copies the design to production. Not quite fair to the designer who put in the effort and expense to create it.

You have to watch out for those guy's in China. I'd hate to see just another product with the label showing them as the manufacturer.

Steve is smart enough to prevent this from happening. I just made it clear that confidentiality for any sensitive information would remain in check at my end. Thanks for understanding that.

Mike,

I do hope that you actually go ahead with this project and give us a perspective as to the results. It would be a great help if not only you but a few others would do this and compare notes. This would sure bring new light to this issue and I believe that all who try this concept will be absolutely delighted that they took the time to do so.

The actual cost for MDF is very affordable for the DIY builder. If you have a table saw with close tolerance accuracy, a drill, and some basic measuring tools, this is all that is needed to make this project happen. (a tad bit of skill and patience doesn't hurt either)

Anyway, I will try to answer any questions regarding this that you may have, and say good luck and happy building!

Paul
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Re: Current listening_evaluation room acoustics
Reply #16 - 11/19/08 at 02:37:33
 
RFZ_Quest - Quite a listening room. A bit larger than before. I'm curious about the floor treatments under and in front of the speakers. What effect does having mats and foam underlayment have on the sound quality? I assume the mats are resonance related. As to the foam -- is it a purely theoretical action or do you notice a difference? I ask as I'm completing my room and have wondered about the effects of having a framed wood floor.
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Re: Current listening_evaluation room acoustics
Reply #17 - 11/20/08 at 18:58:07
 
Tim,

Yes it is completely different from anything I've tried in the past. The overall volume is significantly greater which is a big plus. The actual material, shape, and layout of the room is actually in my favor as well.

This room was a major problem child with the HDT MK2's in the lower end prior to the acoustical treatments. It was so bad that the speakers could not be used in this room with the ToriMK2.

I can now press these speakers hard with that amp at 75% in line with the CSP2 also operating at 75% as a test to see how far these would go without bass issues. The results show that the volume can be increased with consistent levels of stability. I have produced 20 Hz SPL checks @ over 78 db in this room, with overall sound levels averaging 108 dB without any offensive degradation in quality.

This is much louder than what I usually listen to, but the point is that prior to my treatment, I could not play these speakers in this room at ANY volume without the bass sounding bloated and overpowering.

The max that I could tolerate was about 1/3 volume, and that depended on the material played.

I have many types of speakers to use, including the standard HDT models with the DFR8's which would give much better results in this room. The point is that I took on the worst case scenario to see what it takes to correct the compatibility factor. Then anything else should be ideal or even better theoretically.

What I'm doing right now is temporary in form as I am testing different principles to determine the possibilities of certain layouts.

As the floors are all hardwood throughout the listening area, it was best to put some type of absorption down to control the immediate reflections in front of the speakers. It changes the reverberant factor of the room in relation to what is reflected from the other bounderies.

Of course this changes the ambience of the room with a better sense of imaging.

The tests push on with spectacular results so far!

Paul.
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Re: Current listening_evaluation room acoustics
Reply #18 - 12/09/08 at 04:20:36
 
Paul,

Yet again I should have read Steve's white papers before asking a question. Thanks for the reply! It seems that room treatments are somewhat analogous to simultaneous and multi-dimensional games of pool, with lower freqs tending to have quite a bit of spin.

After checking out the comments on the new ERR's, and ones in this forum, I've decided to permenently locate the RL3's in my own great room (instead of the little upstairs bedroom as planned). Will be making full use of diffusors and absorbers †-- fortunately, the speakers are in front of an easily treatable high wall and the room's sides can be softened by letting down the fabric woven window shades, effectively creating 6-inch deep diffusors (if I'm not mistaken). Still mulling over the rear fireplace situation though (a huge brick and metal structure about 20' from the speaker fronts) ... that'll be a challenge, but no problems in the 'wife friendly' arena at this time ... we're both just enjoying the sound!

Keep us posted! Pics are great - really helps. Room treatments need more press.

Tim
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Re: Current listening_evaluation room acoustics
Reply #19 - 12/16/08 at 14:46:07
 
Very impressive. I intend to build something like that by myself too. But if I'd cover the entire front wall with speakers, that could save me from a lot of trouble. Do you think the diffusion speakers could replace these walls?

Regards,
Wolfgang
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Re: Current listening_evaluation room acoustics
Reply #20 - 12/18/08 at 22:04:13
 
Wolfgang,

Not sure what the "diffusion-speaker" concept involves, but I have serious doubts as to it's general feasibility for this purpose.

If it is what I imagine it to be, then at best I would speculate very slim diffusion factors when compared to properly designed diffusion modules.

Of course, any diversion from a flat wall surface is going to provide some degree of diffusion. Actually, the effect uncontrolled is more like that of random reflection rather than that of true diffusion. It is usually in the form of non-unity in it's spread pattern and reduction of delay. †Offset, or canted wall techniques, book shelves, furniture, etc., offer only a limited degree of enhancement when the factors of diffusion coefficients come into play.

With predetermined factors based upon mathmatic calculations for which to center precisely upon a desired coefficient rating, we know with close proximity what to expect in overall performance for a well modeled design.

Not all diffusion concepts or designs are created equal. There are many variances which separate the performance rating from one design to another.

For instance, some designs are based upon a specific limited range as that is the area of concern for it's use. For a broader bandwidth and greater coefficient factor, designs require much larger and far more complicated †design parameters. †

Many do not understand the complexities of how and why diffusion principles work. It is important to understand this in order to build and utilize these units in order to have any sort of predictability as to the outcome of their use.

If one was to build a unit corresponding to 'Half-Wave' measurements instead of the required Odd-Quarter-Wave parameters, the unit would virtually be rendered useless. The unit simply would not work, as the timing would nullify the effect desired in the sequencing factor.

A good diffusion sequence will provide an even spread in time over a large area as opposed to the original wavelength of the incident sound impinging upon it.

The diffusion principal is based upon number theory sequencing in specific order and of specific design. The calculations are always prime numbers arranged in sequence of ODD-ORDER-Quarter-Wave function in order to work effectively.

Just merely creating random surface textures offers very little benefit by comparison.

Remember, if the surface of the diffusion module is not hard enough to block the sound from penetrating it, it would be unlikely that the sound could be redirected properly within a diffused pattern back into the room. Otherwise, the result becomes more of a refraction or even an absorption effect with totally different results than what was expected.

There are so many variables to consider when designing diffusion modules. It is very easy to build them incorrectly with less than desirable results when parameters are not in accordance with the math that dictates their potential.

Hope that gives you some sort of food for thought concerning this issue.

Paul.
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Re: Current listening_evaluation room acoustics
Reply #21 - 01/19/09 at 14:05:21
 
Dear Paul,

What do you think of this diffuser? http://www.rpginc.com/products/diffractal/index.htm

Will it help in diffusing the sound, or should I rather stick to more complex ones based on mathematical calculations?

Regards,
Wolfgang
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Re: Current listening_evaluation room acoustics
Reply #22 - 01/19/09 at 14:57:25
 
The RPG nested grouping in this diffuser is an excellent approach.  It is however complex to build.  It is based on the same quadratic theory as all prime 7 sequence diffusers, meaning it is solidly based on math.

Steve
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Re: Current listening_evaluation room acoustics
Reply #23 - 01/20/09 at 09:03:19
 
Thank you, Mr. Deckert!
I assume I will need to use MDF. At the very small parts I definitely won't be able to use wood anymore. What material would you recommend?

Sincerely,
Wolfgang
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Re: Current listening_evaluation room acoustics
Reply #24 - 01/21/09 at 01:39:51
 
I believe they have the plans available for the RPG on their web site.  In theory the well dividers should be as thin as possible.  

Steve
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Re: Current listening_evaluation room acoustics
Reply #25 - 01/21/09 at 13:01:26
 
Mr. Deckert,
They do show the length and width of different models, but that's about it. I don't suppose I can simply choose the length of each well by myself, although some people already have at other forums...
PS: Do I really need well dividers concerning the very thin wells? One well is less than 1 mm wide. Can't I just use wood at different lengths and make undivided steps for the wells?

Kindest regards,
Wolfgang
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Re: Current listening_evaluation room acoustics
Reply #26 - 01/22/09 at 21:00:34
 
Hello Wolfgang,

The unit in question presented by RPG Systems is a complex integrated design, which is basically a diffuser within a diffuser concept. This means that multiple stages of diffusion is built-in together to form a very wide coverage of the audio spectrum.

The first stage consists of a lower prime designator, which sets the stage as †'building blocks' for the more intricate second-stage sequence within each of the initial lower prime wells.

Each of the large prime-7 wells actually becomes a discreet diffusion module within it's own boundary.

The benefit gained from this approach is that a much wider degree of diffusion coefficient can be realized in a very effective manner. It is simply a means of integrating multiple diffusion elements into one high performance model, which is truly wide-band in coverage.

BTW: All RPG designs are based upon highly complex number theory sequences. The people behind these designs are the most respected in the industry. I have yet to find any of their products as anything less than ideal!

There are calculators available for this purpose with the Modulo function in memory. With this function, number theory sequencing becomes a simple procedure based upon the prime number setting of choice. Steve provided an earlier example of this when he displayed a variation of my design, broken down into the exact mathematical equivalent for which to duplicate within close proximity.

Just follow the numbers and connect the dots. The end result will reflect the degree of accuracy in the design build.

What RPG did is rather simple in design although it becomes more of a challenge in construction.

Something like this concept usually requires a large wall based integrated system due to the layout required. The outer shell is based upon 'lower' Prime number theory, with more complex prime configurations built within each of the primary wells.

If you want to build something like this, you have options at your disposal, which allow for a wide degree of flexibility in overall design parameters.

A system like this is like building a complex crossover network for a 3-way driver speaker design. You are actually integrating multiple 'crossover points in unison to cover the largest range of the frequency spectrum as possible in an effective manner.

I have strongly desired this type of concept for quite some time. This level of build is reserved for the full-scale approach. This is when the walls themselves become the building platforms for which the transformation takes place AS the diffusion element, rather than a backdrop for mere enhancement placed in front of it.

The general rule for diffusion coefficient performance is this: The 'deeper', and the 'narrower' of the well layout, the higher degree of bandwidth coverage possible. The higher the Prime number, the higher this layout grows in significance.

The parts layout, which went into my Quad Prime-23 unit, is staggering in size, weight and cost, due to its complexity. It is however, worth every bit of its trouble in building as the performance quality is equally staggering by the impression it relays. My unit maintains a complex blend of absorption as well as diffusion principles, incorporated effectively into one large-scale design.

If you want the design parameters to replicate something along RPG's design, I can easily formulate a respectable clone with the flexibility of options to choose from.

To keep things on a practical perspective, the basic design parameters must be considered and adhered to.

Space and size is always going to be the first and foremost thing to consider. The overall effect and degree of performance obtained within a practical platform will then become the second factor for which to base your design build.

You must first decide the exact level of performance required meeting your goal, and whether or not this level of performance can be utilized within your space requirements. As you can imagine, a full sequence of wells built within each of the primary wells automatically dictates a considerable amount of real estate. It is however, a fantastic design principal with very efficient results. I would highly recommend this concept if you are willing to build it correctly.

I suggest a maximum configuration of a Prime-7 base platform, with a Prime-13 sequence integrated within each of its wells.

If you wanted to build a massive unit encompassing the entire size of your wall, this is where the unit advance's to a triple stage, extreme bandwidth layout where shear size is necessary to make it possible.

This means that you have actually placed a full prime number sequence 'within' an individual well of another sequence, again WITHIN another individual well of the primary base sequence.

How's that for coverage on a grand scale!

BTW: ALL dimensions are critical in respective to the outcome of the units performance. Whatever the parameters are shown as the result of the math is what you MUST adhere to or this all becomes an expensive waste of time with very little relevance to it's outcome.

I cannot stress this enough! You either have a unit that does what it is designed to do by strict adhesion to accuracy, OR a unit, which simply LOOKS the part but does very little to nothing by comparison.

For maximum effectiveness, it is imperative that full divider panels are utilized between the wells when a quadratic-residue design is considered. You could eliminate the use of divider panels with 'Primitive-Root' Sequencing. This will never perform on the level, which the more sophisticated quadratic principle provides.

Sorry, there are NO shortcuts here if you want maximum performance. The rules are dictated by the laws of Physics. It is as simple as that!

Follow the golden rule precisely and you will be rewarded for it in the end. Ignore this fact and you will return to where you started from.

So, the question is this;

Where are you willing to go with this layout and what is your ultimate objective?

Give that a good deal of consideration, then focus toward accomplishing your goal.

I believe that I can lend the information you seek to accomplish this task. This I can provide as time allows.

Never be afraid to push the envelope of possibility as long as knowledge and dedication remain on your side!

Paul.

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Re: Current listening_evaluation room acoustics
Reply #27 - 01/25/09 at 19:07:19
 
Dear Paul!

I am looking for something to cover two 6 meters long walls for wide range diffusion. I want the best possible sound quality with whatever effort it will take me.
(I have posted a similar letter in the other topic about room treatment actually, sorry...) I post here to answer the questions and because I didn't quite understand something with these prime numbers. Do you mean that one well is 7x (When x is the longest distance that space allows) deep, the next one 11 and the next one 13? And the distance is measured from the very front? I thought this would work only with the fibonnachi numbers. Well, I'm not very sure I understood. I would be very happy if you would help me out. Thanks a lot again for your hints.


Sincerely,
Wolfgang
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Re: Current listening_evaluation room acoustics
Reply #28 - 01/28/09 at 07:10:03
 
Wolfgang,

I'll try to answer this as easily and to the point as possible.

The Fibonacci number system ironically holds a very strong correlation to just about all natural factors in life, thus of which I'm sure maintains a bit of relevance towards the harmonic qualities of music within itself.

However, I think there is a bit of confusion here toward the principal in question and how that it affects the outcome of QRD parameters.

The Fibonacci system-starting sequence begins with zero followed by a one. Each subsequent number is equal to the sum of the previous two numbers of the sequence itself. I.E. After two starting values, each number is the sum of the two preceding numbers.


Our system of concern for determining quadratic residue diffusion sequences is based upon prime numbers exclusively. The prime number (modulo N) determines the length of the periodic sequence (the number of wells that the sequence consists of).

The greater the number of wells (per increasing prime value), the greater the frequency range in which the diffuser is effective.

The deeper the wells are, the lower the extension toward the lower limiting frequency at which sound can still be diffused effectively. The depth is determined somewhere around one-half the wavelength of the lower limiting frequency.

The well width determines the extension of the higher frequency cutoff. This is calculated at a 'half-wavelength' based on the shortest wavelength to be scattered. Whatever the highest frequency you desire to base your workable diffusion coefficients upon, thus becomes the shortest wavelength for which to determine your well width.

If you desire an extension of 20K, then you simply divide the speed of sound in air as the medium (1,130 ft per second) by the frequency to determine the wavelength. In this case we are looking at a figure of around 0.05 in which to base the well width on.

These prime numbers are 2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61, etc....

With these, we have the basis for determining a feasible unit for which to meet our objective within the periodic, quadratic type of diffusing system.

The well depth sequence is determined from the quadratic residue sequence, based upon a prime number, N. This is known as the well depth proportionality factor which = n2 MODULO p.

p= a prime number & n= a whole number between zero and infinity.

Modulo simply refers to residue. This can also be related to the expression: "the remainder after dividing by".

Example: If I wanted to design a QRD based upon the prime # 29, I would come up with the following sequence for which to determine my well depths.

well 0=0" depth.
† † † 1= 1"
† † † 2=4"
† † † 3=9"
† † † 4=16"
† † † 5=25"
† † † 6=7"
† † † 7=20"
† † † 8=6"
† † † 9=23"
† † † 10=13"
† † † 11=5"
† † † 12=28"
† † † 13=24"
† † † 14=22"
† † † 15=22"

† † † 16=24"
† † † 17=28"
† † † 18=5"
† † † 19=13"
† † † 20=23"
† † † 21=6"
† † † 22=20"
† † † 23=7"
† † † 24=25"
† † † 25=16"
† † † 26=9"
† † † 27=4"
† † † 28=1"
† † † 29=0"

Always start with a 'zero-depth' well factor at the beginning of the sequence. Your final well in the sequence will always terminate as a zero-depth well, which means that there is actually one more well than the prime number it is factored upon. This is due to the fact that the sequence starts with zero and not one.

When two periods of this sequence are repeated, it is only necessary to have a single 'zero-depth' well between the two periods. It is also desirable to design the zero-depth wells at half-width of the main wells when possible.

All of these measures benefit in the reduction of periodic lobing, which is a major problem with QRD designs when continuos periods are fashioned. I will touch on this factor later as it is always of primary concern when designing the best possible deterrence towards lobing effects.

I will continue with this later. Don't worry about all of this technical detail. I just wanted to clear some things up about how these things are designed and what makes them tick.

We will get to the most important thing that only matters in the end. You will get the choice of building the units best suited for your purpose. The most difficult thing for you to decide on is the extent of methods used in the total scheme of things. Then you simply build it.

Hope that at least clears up some of the technical aspects in question.

Back with this soon.

Paul.
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Re: Current listening_evaluation room acoustics
Reply #29 - 01/28/09 at 18:39:04
 
http://www.digitalaudiorock.com/cgi-bin/qrd.cgi

You can plug your numbers into this.  

John C.
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Re: Current listening_evaluation room acoustics
Reply #30 - 01/29/09 at 08:49:04
 
Hi Everyone,

Thank you John for the calculator. It sure will be useful.
I'm just gonna step out of topic for a while and ask; about how much would the wood (MDF) cost for a diffuser 4' x 2' feet large and about 1.5' feet deep? All I need is a guess.

Wolfgang,
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Re: Current listening_evaluation room acoustics
Reply #31 - 01/29/09 at 14:47:56
 
Dear Paul,

About the diffusors: What do you think of the Skyline diffusor? I always thought it's not a good one, but at rpginc.com they say it's the best one they can offer.
http://www.rpginc.com/products/skyline/index.htm

On the same site I found a bass trap with a membrane which turns the sound energy into kinetic which is easier to stop. I don't have a lot of place for bass traps because of a door, so would this one do it instead, and can I build it by myself?
http://www.rpginc.com/products/modexcorner/index.htm


Kindest Regards,
Wolfgang
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Re: Current listening_evaluation room acoustics
Reply #32 - 01/30/09 at 05:50:07
 
You've seen the photo's of the assembled quad prime 23 unit previously in this thread.

Here is how it looks stripped down to the basic frame work.



Here's another view with some of the parts which make up the sequences only within the TOP horizontal sections. This shows about 75% of the parts layout used just in the upper sections. What is seen is mostly the Celetex well sections and a portion of the MDF 1/8th" divider sections. This does not show any of the parts required to assemble the large lower sections.



The use of the Celetex material as shown is optional. This option is reserved for dual purpose absorption properties built in conjunction with the diffuser elements as a hybrid design. †When you want to push the limits of design, this is where it takes you. The wells of this unit actually become diaphragmatic by nature. That is a great bonus when absorption factors come into play for a dual purpose design.
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Re: Current listening_evaluation room acoustics
Reply #33 - 01/30/09 at 07:47:57
 
Quote:
About the diffusers: What do you think of the Skyline diffuser? I always thought it's not a good one, but at rpginc.com they say it's the best one they can offer.
http://www.rpginc.com/products/skyline/index.htm


From what I observe and understand about this design, as with just about any of the RPG products, I would highly recommend them for what they are designed to do. This makes for an excellent product to place within a ceiling grid. It is two-dimensional based upon the primitive root system. The benefit to this is the fact that divider sections are not so critical within a design such as this with the added fact that periodic lobing will not be so much of an issue. I believe that one would be hard pressed to surpass the performance ratios of this design with current designs offered for use in a ceiling grid. That is not to say that something close or even better can not be designed by alternate methods. This does indeed work beyond a shadow of doubt.



Quote:
On the same site I found a bass trap with a membrane which turns the sound energy into kinetic which is easier to stop. I don't have a lot of place for bass traps because of a door, so would this one do it instead, and can I build it by myself?
http://www.rpginc.com/products/modexcorner/index.htm


I absolutely am on board with this concept!! The principle behind this design is very impressive. It is not hard to understand why this type of unit provides such great acoustical coefficients across the audio spectrum.

Absorption techniques are just as important as that of diffusion techniques. This design is an example of high performance coefficients over a very large portion of the frequency spectrum where it counts the most.

I have experimented with large diaphragmatic designs in the past, which were coupled directly into the room corners from floor to ceiling. This provided a spectacular result in itís own with a dramatic transformation within the roomís frequency balance. I have no doubt that these modules will provide that level of improvement when placed properly within the room.

If you do not remember anything else, just keep this critical rule in mind for all of this to be justified.

Know the Minima / Maxima rule! Maintain the Odd-Order Quarter-Wave principal in all of your designs, and placement within the room.

Do that and results should be optimum for you.

I am well aware of the RPG designs past and present. I maintain full respect for what they offer in a technological perspective. After all, I have put many of their designs into practice with great results.

If you had observed the large Binary Grid Diffuser units placed behind the speakers at the top of this thread, you would notice that they are patterned very closely to that of RPG's design.

These are practically clone's with a computer generated grid of binary code that is of the same principal and tactic. This type of unit built with a degree of curved proportion as shown represents a new generation of diffusion design, with vastly improved coefficients over a much greater area of the audio spectrum.

These offer significant improvement over that of the QRD designs in more than one aspect. Not only do they maintain far wider range with superior coefficients, but also they are more effective at closer range within a small room. The detrimental aspect of periodic lobing which is inherent within QRD repetitive placement, is no longer a problem with these modern designs.

Through sophisticated computing techniques, new innovative design standards are quickly placing the old QRD & primitive root based designs into obsoletion. The movers and shakers behind this technology just happen to be a major influence behind the information focused upon within the well-respected Master-Handbook-Of -Acoustics series of publications. These movers and shakers just happen to be those responsible for RPG's success.

The major drawback to actually acquiring products from RPG is that of cost. If you can afford these products then that is fine. I think that the average audio enthusiast will have a hard time justifying the total cost for these products on a large scale.


If you understand the principles and how to put those principles to work for you at the greatest benefit possible, plus have the ability to build your own versions with respectable accuracy, then it is of your best interest to build your own when budget restraints are the deciding factor.

That is what we are doing here. The best techniques are considered as the basis for design, while cost no longer presents prohibitive barriers for which a designer must place limitations. The bang for the buck ratio here is of tremendous value within a very affordable outcome.


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Re: Current listening_evaluation room acoustics
Reply #34 - 02/02/09 at 06:46:27
 
Dear Paul,

Unfortunately I cannot afford to build the RPG diffractal and should be looking towards something simpler. "Hotsauce" posted a link to a calculator for diffusion walls.
http://www.digitalaudiorock.com/cgi-bin/qrd.cgi
What range should a good diffusor work at? Is it enough, starting at 300Hz, and do I need it to go up to 20KHz? Close to the ceiling and floor I understood I'll need vertical diffusors. What range should these go for?
And how many wells should I be aiming for?


Kindest Regards,
Wolfgang
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« Last Edit: 02/02/09 at 06:49:00 by Azul Shiva »  

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RFZ_Quest
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Re: Current listening_evaluation room acoustics
Reply #35 - 02/03/09 at 17:56:12
 
This will all be addressed at the following link:

http://www.decware.com/cgi-bin/yabb22/YaBB.pl?num=1233352097

Thanks.
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Re: Current listening_evaluation room acoustics
Reply #36 - 02/12/09 at 20:15:27
 

Great thread! I'm glad I've wandered into here after many, many years of being away.

I'm a big fan of Decware design concepts, and have been chatting on and off with Steve for over 10 years now.

I've unfortunately had to give up two channel listening for a while, but am branching out into 7.1 Home Theater, and I'm looking to kill some flutter echo in my theater room without making the room sound dead. So I'm looking into building some wall hangable QRDs.

I'll keep an eye on your new thread, Paul. Thanks for sharing!
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RFZ_Quest
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Re: Current listening_evaluation room acoustics
Reply #37 - 02/13/09 at 21:36:24
 
Hello Lonely Raven,

Welcome back and thanks for the interest. It would be great for you to become directly involved with some of these projects, gaining from them first-hand, rather than just reading anotherís review of the results. Why not let it be you that post the review regarding the huge transformation that is obtainable within your listening sessions? Too many people have been sitting on the fence regarding the very thing that will make the most difference in their perception to music reproduction.

I hope that this inspires you and many others to get involved. After all, you guy's are the ones that receive direct compensation for your efforts. The resulting benefits can be quite substantial. For many, the results will extend beyond expectation.

I understand about the multi-channel choice. Both worlds can be integrated with great success, so nothing really has to be given up in either regard.

Not only will I be discussing QRD concepts and design builds, there will be focus concerning advanced, next-generation number theory designs as well.

The modern advancement in design allows for many benefits to the end user.

This ranges from much better performance, to that of a lighter, slimmer profile with clean surface lines. Better performance with improved aesthetics in a package that is much more user friendly, at a build cost factor that should fit the average budget very well.

The d.i.y. approach is extremely practical when it comes to projects such as this. You are practically building these units for a mere fraction of their actual worth.

This is where the affordability issue becomes a NON-issue! There is no reason why someone cannot reach the goal of obtaining adequate acoustical control once cost is no longer the major reason for holding off.

The next general excuse for those that hesitate seems to be that of room decor and aesthetic acceptance in general. This all depends on how skilled the installer is along with the degree of creativity for which governs the outcome of this.

Great results require great effort! The rewards here greatly out-weigh the effort-cost ratios that go into a major project such as this.

I will be covering ways to approach the control of flutter echoes somewhere along these project lines. It is a very important issue to deal with which is really not that difficult to correct. Remove the cause and you remove the effect. Just like extinguishing a fire. Remove any or all of the elements which feed the fire and the fire goes out. Pretty simple right? It can be if approached correctly.

I hope that something offered from this thread will result into the ideal solution for your needs. There is no mystery here. Just the application of proven methods put to work in a manner that best suits our needs.

Paul.

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Re: Current listening_evaluation room acoustics
Reply #38 - 02/13/09 at 21:46:29
 
Quote:
This thread is dead (I think). Check the link posted by paul (RFZ_Quest) above


As far as I'm concerned, this thread is not dead yet nor do I intend for it to die out any time soon.

This is a general thread here to post general responses or whatever comes to mind. I just do not want to cover any technical details here when it will be placed in the dedicated project thread.

General discussion here frees up the clutter which distracts from the outline of the project thread. This helps a great deal in keeping some sort of structure and order in place.

Hope that makes sense.
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Re: Current listening_evaluation room acoustics
Reply #39 - 02/19/09 at 21:38:44
 
Thought I might show some of the other experimental configurations that I evaluated in this room prior to moving out of that residence.

Each set of speakers revealed a totally unique signature as would be expected. This room set-up allowed these speakers to perform on a level, not usually experienced in the typical home environment.

Room acoustical behavior proves time after time to be the determining factor in how well the sound quality of a system is perceived.

There was no exception to that fact here, as quality level consistently expanded to new heights, beyond my previous endeavors. It will really surprise you as to what is possible from these variable-testing platforms.

This whole set-up was just that. This allowed me to perform listening evaluations free from the usual restrictions typically imposed in most household situations. The outcome was most favorable to say the least. †

I no longer have this set-up, as this was only a temporary situation.

This allowed me to try many variables that were previously unobtainable. The purpose was to show degree of effect for which any or all of these measures proved to provide. It definitely reveals the influence for which any or all of these combined tactics contribute to the overall room response.



These speaker mock-ups were quickly assembled from leftover prototype cabinet sections as a testing platform for a new concept that I wanted to try.

These are a dual chamber concept for which separate enclosures work independently for discreet frequency enhancement. As seen, these have the new variable rate ports for the passive loaded drivers.

These are ported at both sections, which one is at the top and the other is at the bottom. It is in the way that the two sections are isolated that makes them work so well.

A strategically well-placed baffle section is placed behind the DFR-8 drivers. Above the drivers, I built special barrier plates, which contained inverted radial cones with sealed centers; similar to that of the passive radiators used in the upgraded HDT models.

The upper chambers simply had a matching hole with a sealed circumference for which mated directly to the passive radial cone perimeter on the lower chamber. The loading that occurred from this set-up proved to be exceptional, and very worthy for future consideration in design tactics.

I could have really screwed with peopleís minds by listening to this set-up. If it were a blindfold test, one would be in utter shock once the visual aspect comes into play. †It was a huge surprise to me! In this room, the experience was satisfying well beyond expectation.

These speakers turned out to be some of the most impressive sounding design concepts that I've experienced to date! I set them up for which was supposed to be a short and simple test for a new design that I am working on based upon the DFR-8 driver. †The idea was to test the gain provided by the top loaded chamber, in order to see if this concept was worth pursuing. The results proved clear as to the significance of its enhancement.

These remained in place for just over TWO WEEKS! I found these to be extremely entertaining in all aspects. So much, that I did not want to take them down. As crude as these were in form, the overall synergy proved to be one that works extremely well. I can only imagine how much greater these could be if advanced R&D were introduced to this concept.



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Re: Current listening_evaluation room acoustics
Reply #40 - 02/19/09 at 22:39:35
 
Here is a wide, expanded view of the room layout tested with an early version of the retail Radial Towers. The pair shown here is the only set in existence enhanced with the greatly improved modifications that these have.

This set was recently sold for a fraction of its worth. I'm sure that the new owner understands this in a way, only possible through experiencing their unique sound character first hand. If I had not been in a situation forcing me to sell these, I would never have done so.



You can see the additional treatment that I placed along the upper portion of the room's perimeter. I just happened to have a large supply of these webbed air pillows that were used for shipping protection. I strung these up along the entire section above the speakers in order to test the reduction of flutter-echoes as a result.

I filled the entire corners with sealed cylinders in order to remove bad artifacts, typically compounded by room boundaries. In addition, I built a hanging absorption pod in the center of the room which acts to break up ceiling/wall disturbance.

These last seemingly simple modifications proved to enhance the rooms imaging qualities by a very large margin. The improvement was immediately noticeable with strong significance.

This really cleaned up upper-frequency artifacts, with a sense of clarity unrealized in prior tests. I can tell you that spatial information took on a refined sense of relaxed state, seemingly natural in overall presentation.



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Re: Current listening_evaluation room acoustics
Reply #41 - 02/20/09 at 01:45:49
 
Here is another stage of testing involving a set of retail 'Kadence' models.


These are of premium design and build quality, based upon a twin configuration of full-range drivers within a transmission-line concept.

Remarkably efficient, unprecedented in form, these bear strong presence among the finest of speaker designs.

Offering a degree of speed that others merely hint at!






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