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Fireblade's Diffuser Build Log (Read 7504 times)
Lonely Raven
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Fireblade's Diffuser Build Log
04/02/15 at 15:39:35
 
OK - in another thread we were talking about diffusers, as you know I like to do.  :)  Fireblade asked if I could offer some suggestions, he wanted to build some diffusers to try out in his absorptive treated room. I figured this would be an ideal opportunity to use this for a build log.

The concept and design of diffusers is quite easy, IMO. The goal is twofold. #1 and most obvious is to diffuse the reflected sound - which offers better frequency response at the listening position. #2 is *time delay* to help with the muddied, smearing of the direct speaker sound. This time delay is was helps your brain filter out the reflected sound from the direct sound. And that's really want we want, we want to hear our direct sound, without deadening the reflected sound, and we get the advantage of more even frequency response at our listening position!

The problem with absorbers only, is that it's terribly unnatural. Our ears/brain evolved to listen to the timing of sound as it passes both your ears. That (approximately) six inch space between your left ear and right ear is all the brain needs to locate the direction and distance of the source of a sound. So absorption only allows you to hear the direct sound better, but it sounds odd to us because the instruments that make up our music, aren't played in a vacuum. There should also be spacial queues involved in the delayed reflections that help our brains paint a picture of that instrument, it's harmonic content, and the room it is playing in. That's where diffusers come in.

So we need a few things for a successful diffuser. The key points are depth, width and number of the individual wells, and the width of the overall device. Depth helps with the time delay and low frequency diffusion. The width ties in with the depth to define how low the diffusers can diffuse. And the width and number of the individual wells define how high in the high-frequency we can go. Our goal is to go as broadband as possible within our space, budget, and builder skills. If you're buying diffusers, then they also have to figure in shipping  costs and limitations (think of the Decware diffusers). There is A LOT of math involved in figuring this all out. It's not *random* like some pages would have you think. There are limitations as to how deep a well can go before you *need* to widen the well. There are (physical) limits to how small the width of the wells can before before air viscosity becomes a problem. And of course, if you make them too complex (like my design for my personal ones), you have to have the skills, tools, and shop to be able to build them accurately!

Thankfully there is a great software tool out there written to do 99% of the math for us - we just need to define what we can fit in our room, and build with our skillset and budget. That tool is QRDude created by my (online) friend who goes by the screen name Collo. You can find this software here:

http://www.subwoofer-builder.com/qrdude.htm

With this software, we can build devices that are effective from around 275hz, up to just over 12khz. But they'd be HUGE and complex. (like my personal design that I have been able to successfully build LOL)


So, my questions for Fireblade:

How deep can I go on these? I'd personally say a minimum of 6", but we could go up to 13" deep. Again, that's DEEP. The deeper we go, the wider these are also going to be.

Next question, width and height. Height doesn't affect the sound really, only the wall coverage. So taller the better - but you can also stack two smaller diffusers to make one super tall diffuesr if that suits you. Width is the important factor. Typically I shoot for 2' wide. If you need more coverage, you simply build more diffusers.

Lastly, complexity! I would love if we could all build 3' wide, 3' tall, 12" deep broadband diffusers with 29 1" wide wells!! But it's a PITA to get that much wood cut accurately, *And* assemble it accurately. I've not been able to do it for myself - but I'm also a whimsical slacker. I get really into the build, run into some issues I didn't count on, get frustrated and put it aside for a while...or years.

The diffuser I designed for Palomino was 6" deep, ~ 1.5" wide wells, and has 13 individual wells - so I believe it's just under 24" wide - it's range is really only 697-4777.  If you're up for it Fireblade, we could push that a little further. Say 8" depth, 1" wells, and QRD 19! This would have an effective range of 646hz-6880hz!

To be continued -
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« Last Edit: 04/03/15 at 15:23:36 by Lonely Raven »  
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Re: Fireblade's Diffuser Build Log
Reply #1 - 04/03/15 at 15:42:13
 
OK, I've not heard from Fireblade yet, but i have a few minutes to write, so lets forge on.

Let's take my QRD 19 example above, and plug in my desired settings to QRDude (I hope you guys are playing with with by now - it's a bit of clicking, and a bit of leap of faith, but the program really can make it easy if you understand *your* design concepts).



In this image, you'll see I plugged in my desired settings. My goal, is to build a diffuser similar to what I designed for Palomino, but with more high frequency diffusion. This is a more complex build to be sure - so I'm not sure Fireblade or ProggRob would be interested in this build, but it's a good one to do. Now, since I kind of know my way around the software, at least enough to get what I want out of it (there are some awesome features that go over my head!), I'm running this very manually. I've set number of wells to 19 (QRD 19), I've set my depth to 8", and I've manually set my well width to 1". If I let the auto-optomize do it, it sets it to 1 1/16" - which is still good, but I wanted to hit that magic 6880Hz number...because that's the highest these diffusers can physically go. Now, I've also go Optimize set in the options - so if you look at the bottom left, that wheel looking thing - the software has automatically calculated the most efficient well pattern for my 8" depth. If you look at the green and grey top-down diffuser drawing, it looks like there is 4 boards on the back of the diffuser...that's how much space the software is saving me. I'm getting more broadband range (like a 10" deep diffuser) out of 8" of depth! Looking at the middle, the light blue lettering tells us what we just designed.

Scatter 323Hz Diffuse 646Hz HF Cutoff 6680Hz
Minimum Distance to seating - 5' 2 7/8"
Period Width 1' 9 1/4"

So - here is what this is telling us - it's diffusion range is around 646hz - but we get a little extra out of our diffuser, because technically it can "scatter" half below it's lower diffusion, and *twice* above the highest diffusion. So while it diffuses between 646 and 6680, it's still scattering down to 323hz and up to 13360Hz! That's pretty broadband for some strips of wood, huh?

This is also why I call BS on people that say "Oh I've got some books on the back wall", or "I have this textured rock pattern", or "oh, just randomly glued some wood to this board and hung it up on the wall". The first two are BS, because a bunch of books probably only diffuse in a very narrow band of 2000hz to 4000Hz (using QRDude to help me guess there) and a bumpy rock wall 4200hz to 6000hz. It's such a narrow band, it probably sounds beamy. And random wood diffusers only advantage is that it would break up flutter echo between two walls...everything else about it is *random*. Although I'd be impressed if someone went whole hog and did 14" depth, 8' X 8' random diffuser. That's where you'd start approaching something effective compared to our simple, calculated 1D diffusers!

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« Last Edit: 04/03/15 at 15:54:38 by Lonely Raven »  
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Re: Fireblade's Diffuser Build Log
Reply #2 - 04/03/15 at 16:02:50
 
The software can also generate a report, so you can have the specs printed out, including the well depths and all that. You can see it even balks at me for changing the well width from 1 1/16" to 1" - If I were building this for myself, I'd do whatever is easier for me in the shop - the effect is still going to be good, just don't stray too far away from specs!

Deepest well in inches: 8

Fin width in inches: 1/8

Width of wells in inches: 1

Ratios       3       4       7       12       0       9       1       14       10       8       8       10       14       1       9       0       12       7       4

Well depths in inches:     1 11/16     2 1/4     4     6 7/8     0     5 1/8     9/16     8     5 11/16     4 9/16     4 9/16     5 11/16     8     9/16     5 1/8     0     6 7/8     4     2 1/4

Block heights in inches:     6 1/4     5 11/16     4     1 1/8     8     2 13/16     7 7/16     0     2 1/4     3 7/16     3 7/16     2 1/4     0     7 7/16     2 13/16     8     1 1/8     4     5 11/16

Phase shift in degrees       56       75       132       227       0       170       18       265       189       151       151       189       265       18       170       0       227       132       75

Scatter 323 Hz   Diffuse 646 Hz   HF cutoff 6880 Hz

Period width 1' 9 1/4 inches

Minimum distance to seating position 5' 2 7/8 inches (3 times wavelength of lowest diffusion frequency)

Poor result: Period width of 1' 8 15/16 inches is less than the design wavelength of 1' 9 3/4 inches - Lowest diffusion frequency will be higher than design frequency. Well width to fix is 1 1/16 inches

Good result: The well width is large enough to avoid viscous losses

Good result: Plate frequency of  11856 hz is higher than HF cutoff of  6880 hz, so it has no effect

Good result: The HF cutoff frequency of  6880 hz is  11 times the design frequency of  624 hz

True diffusion frequencies:   1248   1872   2496   3120   3744   4368   4992   5616   6240   6864 hz

Current strategy for recommending well width of 1 1/16 inches: Recommend well width so that period width is greater than design wavelength

--------------------------------------------------------------------------------


One thing I'd like to point out is plate frequency - that's the point where at certain angles, the diffuser simply starts acting like a flat wall. 11856 hz - this is unfortunately lower than twice the 6880hz scattering point, so our top end would be around that 12khz range. Seriously, splitting hairs at that point. It would be a kick ass diffuser.
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« Last Edit: 04/03/15 at 16:06:45 by Lonely Raven »  
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Re: Fireblade's Diffuser Build Log
Reply #3 - 04/03/15 at 16:13:43
 

OK, let's do something a little more sane. This is I believe what I designed for Palomino - it gives a good range across the mid-frequencies - which are where most rooms have trouble, and helps clean up vocals and guitar and all that. I let this auto-optomize to get the best range for the space, it's only 13 wells, and wider wells so it's simpler to build. If everyone here had six of these in their room, the world would be a better place.  :)



Data for One Dimensional  QRD (Quadratic Residue) Diffuser

Advanced N13+4,0 panel:    Shifted down 4 depth units

Design frequency  697 hz

Number of wells:  13

Deepest well in inches: 6

Fin width in inches: 1/8

Width of wells in inches: 1 7/16

Ratios       4       5       8       0       7       3       1       1       3       7       0       8       5

Well depths in inches:     3     3 3/4     6     0     5 1/4     2 1/4     3/4     3/4     2 1/4     5 1/4     0     6     3 3/4

Block heights in inches:     3     2 1/4     0     6     3/4     3 3/4     5 1/4     5 1/4     3 3/4     3/4     6     0     2 1/4

Phase shift in degrees       110       138       221       0       193       83       27       27       83       193       0       221       138

Scatter 348 Hz   Diffuse 697 Hz   HF cutoff 4777 Hz

Period width 1' 8 1/4 inches

Minimum distance to seating position 4' 10 1/4 inches (3 times wavelength of lowest diffusion frequency)

Good result: Period width of 1' 7 15/16 inches is not less than the design wavelength of 1' 7 7/16 inches

Good result: The well width is large enough to avoid viscous losses

Good result: Plate frequency of  9061 hz is higher than HF cutoff of  4777 hz, so it has no effect

Good result: The HF cutoff frequency of  4777 hz is  6.8 times the design frequency of  697 hz

True diffusion frequencies:   697   1394   2091   2788   3485   4182 hz

Current auto-well strategy: Auto-adjust well width so that period width is greater than design wavelength



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Re: Fireblade's Diffuser Build Log
Reply #4 - 04/03/15 at 16:38:58
 

So why don't shops sell these like crazy? Why are the Decware diffusers so small...do they work? What's the minimum seating distance? Why don't I like these at the first reflection point? Why, why, why!

So, there are a couple shops that make proper diffusers - but they are stupid expensive, and have special shipping requirements. Acoustic fields comes to mind. Dennis isn't messing around! He's doing it right or not at all. But....well, lets look at the specs.

A solid wood unit that measures 27 3/4″W x 48″H x 12 1/2″D and weighs 105 lbs. when assembled,
Frequency Response: 280 Hz. – 3,400 Hz.

105# and 27" by 48" and they cost just under $800 EACH *before* shipping. And IMHO, you need six to really treat a room. That's for the DIY kit that you need to glue together. Their QRD 19 (see my design above for similar!) A unit that measures 36″W x 60″H x 20″D and weighs 275 Lbs. and $3400 EACH before shipping!

Yeah, they don't mess around, but that's a rich mans game.

Now lets look at Steve's - info taken from the P1312 page

"Diffusion between 1125 Hz ~ 12,000 Hz.

A 12 inch square diffuser tile based on the prime 13 sequence that can be interlocked together to form large arrays and free standing units"

He's opted for the easier to build, best bang for the buck, easier to flatpack, and covers a good portion of the upper mids and high frequency. He's cleverly done the most work with the smallest package.

Do they work? YES! You'll break up flutter, you'll get that high frequency air and detail - but it's going to take a crapload of those little guys. It's all a trade off to get the most bang for your buck. Oh yeah, and I've built my own version from his plans...about 15 years ago(!) which is still hanging on the back wall of my home theater. I basically took the design and instead of lots of little guys, make two bigger ones. These are roughly 2' X 4' and 120# each if I recall. LOL




So the last point - seating distance and why not the first reflection point. Well, the short answer is, that it takes some *distance* for those diffused waves to spread out. If you were to setup a nice QRD diffuser, but it was 2' from your chair, you'd hear this peaky reflection that coincides with the design frequency of your diffuser, and the distance between your ear and the diffuser. Whatever frequency that is, will beam at you...you really need to give the diffuser room to breath. And I feel the same thing happens at the first reflection point - if you don't have some space between the speaker and the diffuser, you'll get some beamy sound as if you had the speaker too close to a side wall. Again, this is another cool thing about the Decware diffuser design, since it's more high frequency designed, I think the minimum distance is something like 2' or maybe less!

That's enough rambling from me now. I hope this helps out some. If someone has some questions, I'll do the best to answer - I'm not a trained acoustician, but I do the best I can with what I've taught myself. I'm sure if we get a real acoustical engineer here he/she would spaz and correct me on a lot of things, but for our needs, what I've posted is a huge leap from not having room treatment. Seriously, once you hear a few diffusers in the room, you'll wonder how anyone can function without them!


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Re: Fireblade's Diffuser Build Log
Reply #5 - 04/04/15 at 15:09:45
 
Hi, I apologize for the delay, have been at work (even yesterday and today), so still not much time to discuss this interesting topic until later on.

If I understand this right, the 8" you are suggesting refers to  the distance between the back of the panel to the top of the highest piece coming out of that panel? In other words, there must be at least that much clearance from the walll and the speaker, right?

In my case that may not be a problem, barely, but the real issue would be the distance from the listening position. As it is, I'm already at barely just over 5 feet from the speakers, so anything placed in between would be a fraction of that distance. So, in my case, the design needs to be more modest, say, 6" and hoping that would be enough reduction in the required minimum sweet spot distance ...

That's about the time I have right now, IŽll get back as soon as I can, probably tomorrow (my only day off, I'm doing some OT to pay for my diverse audio gear needs ...)

Excellent, impressive initiative, LR  :)  . . . Thanks for the patience and kind support.
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« Last Edit: 04/04/15 at 15:14:42 by Fireblade »  

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Re: Fireblade's Diffuser Build Log
Reply #6 - 04/04/15 at 22:25:54
 

Yeah, I understand no time due to work. This past couple months was tough on me too. I used the above posts to take a break from the stress.

Ok, so, just to make sure we are understanding each other, I think I need a couple things from you.

Dimensions of your room. Distance of your speakers from the front wall, and side walls. The distance between you and the speakers. Maybe a photo of the room as well. Just a camera phone photo would do fine. I need to get a sense of what you have to work with. From what I'm reading above - it's almost sounding like you need smaller diffusers, more like the Decware or PI Audio diffusers. But I want to make sure by seeing what you have to work with. Some rooms, just are too small for anything but low level near field listening.
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Re: Fireblade's Diffuser Build Log
Reply #7 - 04/04/15 at 23:02:49
 
Hi LR,

I'm still at work, so just a note ...

I'll make a scaled Excel plant view sketch of my listening room with precise dimensions and geometry, also to indicate the fact that on one side I don't have enough room to have the diffuser as there is a door in the 2nd impact area (I could place an easily removable  diffuser against the door when I'm listening, though).

Anyway, once you see the sketch, you'll understand the context, and yes, I probably need smaller diffusers. Given the smallish listening room dimensions, their impact should be evident anyway, I hope.

BTW, when I earlier said I would start with a synthetic material to build these things, I was thinking about the symmetrical, simple diffuser design, not these topologically dynamic ones, meaning, I'll probably be better off ordering them through a woodshop, as I could not get all those different pieces from a synthetic material vendor, I don't think. Well, just thinking out loud ...

-----------------------------------------------------------------------------

Edit (4/5/15):  Ok, here is the link to the mentioned listening room scaled sketch with all the basic dimensions:

https://www.flickr.com/photos/79730303@N05/

Legend (the scale gray square represents 0.5 ft x 0.5 ft):

ABS = Absorption panel
DIF = Proposed Diffusion panel location
Large Closet = Essentially a closet with both doors open and a bunch of hanging clothes on it
Open closet =  narrow closet with wooden horizontal dividers at different distances with a bunch of smaller things on them

That's it! Any suggestions are welcome. I put tentaive difusser locations in the two spots which are more suited for that duty, but is not a definite location as this needs to be tested first.

I may need two panels in each spot, one next to the other in the vertical axis, to cover a reasonable area on the respective wall or door (the latter would need to be movable as these would be sitting on the inside of the only functional door.

Note: I currently have placed additional thinner ABS panels in the empty spots (approx 1" thick) between the normal ABS panels (4' x 2' x 2", on wooden stands) indicated. The room sounds less lively this way, so I'm planning to take these off and leave the rooom as depicted in this sketch.

Thanks!

Edit 2 (4/5/15):

Removed the additional absorption subpanels covering empty wall spaces with good results. The sound is livelier now and yet no booming or sibilance present, so this is back to my original setting and the one depicted in my sketch.

This means, to me at least. diffusers will be really welcome if these avoid the vices of excessive bare wall exposure and bring out the sort of soundstage and PRATT I would love to get out of the room.

Thanks!
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« Last Edit: 04/05/15 at 21:36:37 by Fireblade »  

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Re: Fireblade's Diffuser Build Log
Reply #8 - 04/06/15 at 20:56:22
 

Fireblade, I'll follow up with you on this today. I can see your drawing, but I'm having trouble opening it up full size or saving it. I'll try again later tonight when I'm out of work and have more time to look at this.
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Re: Fireblade's Diffuser Build Log
Reply #9 - 04/06/15 at 23:04:43
 
I can always send it to you via Email. Just let me know.  Thanks.
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Re: Fireblade's Diffuser Build Log
Reply #10 - 04/07/15 at 00:43:39
 
Yeah, do that please.

LonelyRaven@hotmail.com

Also, is there room between the door frame, and the absorber to squeeze in a diffuser?

Right off the bat, I'm thinking diffusers on your back wall and just behind (towards your seating position) the absorbers would give you the same lift that we get at Palomino's and ProggRob's place.

I'm really concerned about that big window between your speakers. Glass in that critical area is a huge problem IMHO.

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Re: Fireblade's Diffuser Build Log
Reply #11 - 04/07/15 at 02:21:30
 
Message sent.

Is there room between the door frame, and the absorber to squeeze in a diffuser?


I could certainly move the current absorption panel (ABS) closer to the speaker, since these pannels are on wooden stands. But, we may miss the ideal position for the first impact.

I'm thinking diffusers on your back wall and just behind (towards your seating position)


Behind the sweet spot I have part of an open semi-closet and part of an ABS against the wall. If I push the ABS further against the corner, there may barely be room for a small, narrow-width diffuser.

I'm really concerned about that big window between your speakers


That is a Miami window, typical of warm weather places, and I keep it semi-open so it may act as a rough diffuser. Besides, the window is not naked, as it has a very thin curtain and a thick piece of cloth on the top 1/3 area. I also have the left side of the window partially covered with an ABS in that corner. But, you may be right, it may not be enough ...

Thanks!
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« Last Edit: 04/07/15 at 02:23:55 by Fireblade »  

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Re: Fireblade's Diffuser Build Log
Reply #12 - 04/07/15 at 03:47:27
 
Quote:
Behind the sweet spot I have part of an open semi-closet and part of an ABS against the wall. If I push the ABS further against the corner, there may barely be room for a small, narrow-width diffuser.


I get that - but if you're serious about this - I'd get two pair of the PI Audio diffusers like I picked up. They are 24" wide. I'd put one between the door and absorber. either on the wall, or craft a wood stand for it. Then match that on the other side. We need to keep symmetry in the room. The second pair I'd put on tall stands, get them like 24" off the ground and put them behind that sweet spot. They are light, and even on stands will probably only weigh 15# (I'm putting mine on stands after I do some more testing at ProggRob's house).

With this setup, you will get that width of soundstage, keep the energy in the room,  and clear up some of the reflections in the room.

That window in the front still bothers me, but maybe you can leave that for now...once you see what  a few diffusers can do for you.

If you really have your heart set on something made of wood, then build the QRD 13 I posted above. Same plan. Put one each on the side walls, and a pair on stands 24" off the ground at the back wall.
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« Last Edit: 04/07/15 at 03:47:50 by Lonely Raven »  
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Re: Fireblade's Diffuser Build Log
Reply #13 - 04/07/15 at 12:42:53
 
Hi LR, thanks for those pointers.

What about the sitting distance from these diffusers? I'm under the impression  there may not be enough room for the diffusers to do their thing?

I may have some other questions about the specs for that QRD 13, but have not been able to look at that design in detail yet. But, from a building point of view:

1. What would you suggest to fix those elements to the base board wells (glue? what kind?).
2. What do you call a fin (i.e., fin width 1/8")?
3. Are all the wells next to each other? What is the clearance between adjacent elements on the board? Is that the fin width you talk about?
4. What is the well board pattern? I mean, how many rows, how many wells per row? Where does the 13th well (asymmetrical number for a rectangle) fit in?

I'm sorry if these questions seem silly, but I have not even seen one of these things before.

On the Pi Audio alternative approach:

How much are those PI Audio 24" diffusers and how much do they weight? Aren't these too bulky to have them shipped all the way down here? Is it a practical thing to do?

The alternative in wood may seem like the best way due to logistics, but I have yet to find a good carpenter that really cares for precision at those levels  :-/

Thanks again for the support.
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« Last Edit: 04/07/15 at 13:15:32 by Fireblade »  

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Re: Fireblade's Diffuser Build Log
Reply #14 - 04/07/15 at 14:23:05
 
Awesome Questions - I'll do what I can to clear things up for you.

Quote:
What about the sitting distance from these diffusers? I'm under the impression  there may not be enough room for the diffusers to do their thing?


I'm having trouble telling from the drawing - but it looks like 4 feet from the wall to yours ears? I think that's plenty fine for the PI Audio, but a little under for the QRD 13 above. You could get the Decware ones which have an even shorter distance, but they don't go as deep as the QRD 13 above. The PI Audio I believe are somewhere in between the QRD 13 above, and the Decware design.


I may have some other questions about the specs for that QRD 13, but have not been able to look at that design in detail yet. But, from a building point of view:

Quote:
1. What would you suggest to fix those elements to the base board wells (glue? what kind?).

I prefer using plane old silicon caulk. It makes a great glue, adds mass to whatever your sticking it to, and is (obviously) a great sealer.

Quote:
2. What do you call a fin (i.e., fin width 1/8")?


You can do 1/8" of pretty much any solid material for the fins. If you're doing wood, then MDF or plywood if you can find plywood that thin. 1/4" material is easier to work with because it's not as "floppy" as 1/8", but also costs more and adds weight to the final product.

Quote:
3. Are all the wells next to each other? What is the clearance between adjacent elements on the board? Is that the fin width you talk about?


I'll post a link to a video, so you can see the Acoustic Fields "kit". That will help you understand the construction of a typical QRD diffuser.

Quote:
4. What is the well board pattern? I mean, how many rows, how many wells per row? Where does the 13th well (asymmetrical number for a rectangle) fit in?


Look at the drawing and measurements above. You may have to scroll over to see the 13th well.
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« Last Edit: 04/07/15 at 14:37:47 by Lonely Raven »  
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Re: Fireblade's Diffuser Build Log
Reply #15 - 04/07/15 at 14:27:58
 
Quote:
On the Pi Audio alternative approach:

How much are those PI Audio 24" diffusers and how much do they weight? Aren't these too bulky to have them shipped all the way down here? Is it a practical thing to do?


They are foam - which I have mixed feeling about. But the nice thing is, they are only 20# for a box of four!

I paid $160 for a box of four (two matched pairs), and shipping was $72...which hurt, but the total price was still worth the cost of admission. I really like these diffusers for bang-for-the-buck. And it was an investment for me to show others what diffusers can do. I bought 4 pair, two boxes worth, and paid $72 shipping for each box, and it was less than $500. If you can find a woodworker to craft you 4 wood diffusers for between $500-$600, I think you'd be in a good place.
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« Last Edit: 04/07/15 at 14:32:49 by Lonely Raven »  
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Re: Fireblade's Diffuser Build Log
Reply #16 - 04/07/15 at 14:31:26
 
Here is the video I was talking about. You don't have to build exactly like they do, but their method really makes sense from a Flat Pack design for shipping. I'm pretty sure this is how the Decware ones came if you ordered them in flat packs. I was talking to Zygi about how he cut them to get tips for my huge ones I'm struggling with - and it sounds pretty close to this same setup. If you find a woodworker who can build diffusers according to the drawings (show him the video so he understands the concept), just let him do whatever he wants to complete it...it doesn't *have* to go together like this video, the only really important thing is to be as accurate as possible on well depths and widths.

https://www.youtube.com/watch?v=MRvue5ZCiyc



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« Last Edit: 04/07/15 at 14:31:46 by Lonely Raven »  
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Re: Fireblade's Diffuser Build Log
Reply #17 - 04/07/15 at 14:34:55
 
Ok I got it, I think.

I was thinking in one of those difussers with all those cylindrical or rectangular cubes protruding elements in a special array, but those are varying heights across the length, whereas your design has a fixed height across the length, with different heights across ribs but not multiple heights along the length of the ribs.

If this is the case, everything else rings a bell, I think

Thanks!
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« Last Edit: 04/07/15 at 15:20:53 by Fireblade »  

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Re: Fireblade's Diffuser Build Log
Reply #18 - 04/07/15 at 14:40:20
 

Another Acoustic Fields video - if you get bored, fast forward to the end, he shows the equipment he's blowing people away with. You can see the diffusers behind the singer. That's what the QRD 13 would look like. The PI Audio are a little different design, but still pretty effective.

https://www.youtube.com/watch?v=dg3_yOYT4OA

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Re: Fireblade's Diffuser Build Log
Reply #19 - 04/07/15 at 15:20:12
 
I'll do that. I just modified my earlier message to make it more clear.
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Re: Fireblade's Diffuser Build Log
Reply #20 - 04/07/15 at 21:45:20
 
These are the ones I thought we were discussing in the beginning:

http://proaudiotoys.com/images/RPG_Skyline_Diffusor_System.jpg

That last video in the end where the diffusers show up behind the lady sitting, these seem very simple. But unless I view them in another angle I still cannot tell how these are made.
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« Last Edit: 04/08/15 at 00:16:19 by Fireblade »  

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Re: Fireblade's Diffuser Build Log
Reply #21 - 04/08/15 at 00:57:45
 
PI diffusors 2 pair I paid $61.64 fed-x to Long Beach CA.
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Re: Fireblade's Diffuser Build Log
Reply #22 - 04/08/15 at 20:50:34
 
Yeah, I have seen their site, love that Uber Boss too. But, what are your final impressions with these diffusors?  BTW, my logistics concern stems from a lot longer distance shipping involved in my case. Thanks!
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Re: Fireblade's Diffuser Build Log
Reply #23 - 04/09/15 at 16:04:15
 
Fireblade:  I've been playing with placement on the 2 pair PI diffusers and current position is throwing a wider sound stage. They are also making a nice improvement in the details of the music. I plan to throw some base traps up in the ceiling wall corners before looking at additional diffusion. So far absorbers and diffusors are doing what they're supposed to. So I will continue taking it forward in small steps.
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Re: Fireblade's Diffuser Build Log
Reply #24 - 04/09/15 at 18:47:58
 
Thanks for the follow-up. I may give these a try.
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Re: Fireblade's Diffuser Build Log
Reply #25 - 04/09/15 at 22:54:05
 
Fire,  PI will paint them if you wish, and they will cut them down to 2' x 2' sections if that's something you may require. Good Luck!
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Re: Fireblade's Diffuser Build Log
Reply #26 - 04/10/15 at 20:23:00
 
Painting is not an issue. I also think I have room for the 2' x 4' size, at least in two of the three ideal locations in my room.

I'm more worried about the fragility of these things under double handling and very long distance shipping conditions. I'll send them a message and see if they provide some kind of extra packaging and "Fragile" warning for overseas shipping.  

Other than that, these seem reasonably priced and shipping costs may not be that bad considering the Fedex rates inside the US.

Besides, although having a woodshop make LR's suggested design would be great, I still need to find people that can work with the required precision.

Thanks!
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« Last Edit: 04/10/15 at 20:33:08 by Fireblade »  

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Re: Fireblade's Diffuser Build Log
Reply #27 - 06/18/15 at 16:48:46
 
KEEP TWEAKING!!! I moved 2 of my PI audio 2' x 4' diffusers to the back wall 1st reflection points (used to be set horizontally on top of GIK absorbers on side wall 1st reflection).  Wow! the soundstage left and right has increased as well as the height.  I have some tri corner bass traps due soon from PI that I will put on ceiling corners....then we'll see what's next. Loving the improvements! Lesson learned...keep tweaking.
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Re: Fireblade's Diffuser Build Log
Reply #28 - 06/18/15 at 20:48:36
 

Oh yeah, Palomino and I are constantly moving stuff around.

It would be easier if I had a dedicated room - but it is what it is.

Since I might have a very small (10X12) spare bedroom opening up soon, I might just temporarily turn it into a dedicated listening room, to see what I can get from it.

I think the smaller room would hurt my sound more than having the big L-Shaped room. But we'll see.

Hell, maybe I'll swap the master bedroom and the tiny spare bedroom, just for a dedicated room! LOL
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Re: Fireblade's Diffuser Build Log
Reply #29 - 06/18/15 at 21:40:40
 
LR, I think you're right, the small room would hurt your sound in comparison to the L. I had a small room (about that size) as a dedicated room for a long time. But it was a mistake.
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Re: Fireblade's Diffuser Build Log
Reply #30 - 06/19/15 at 19:42:57
 
Quote:
LR, I think you're right, the small room would hurt your sound in comparison to the L. I had a small room (about that size) as a dedicated room for a long time. But it was a mistake.


On the plus side, I have a couple hundred pounds of sound absorbing materal, my old Decware CWALS, and almost enough diffusers to cover 360 degrees around me.

So while the small room would hurt, I have some leverage to make it better.
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« Last Edit: 06/19/15 at 19:43:30 by Lonely Raven »  
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Re: Fireblade's Diffuser Build Log
Reply #31 - 06/19/15 at 20:39:54
 
Okay. I'll never go back into a small room again. Smiley Even with treatment. . . it's just not a comfortable option for me. I am so done with near field listening.
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« Last Edit: 06/19/15 at 22:35:23 by Lon »  

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