Show us your diffusers!! - Home Theater Forum and Systems - HomeTheaterShack.com

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post #1 of 23 Old 01-13-10, 08:52 AM Thread Starter
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Show us your diffusers!!

I love the looks, design, and construction of sound diffusers. I'd love to see what you've done, or any photos you may have of someone else's rooms with diffusers.

Here are a couple of my own that I still have around...and I'm working on quite a few more over the next few weeks!


I have two of these that I built from the Decware sound diffuser plan. I modified the plan to make 2'X4' panels vs 2' X 2', and I built them using scraps I had around the shop at the time. So it's a mix of 3/4 and 1/4 MDF when it probably could have been a lot lighter weight having used 1/8" fins. They still work decently, though are only about 4" deep.




Then, after being inspired by another diffuser build thread in one of the many audio forums, I decided to copy what he was doing and make some "flutter echo" breaking diffusers. I literally took a drawing from a book, scaled it up, took measurements, and started cutting to match. These are also built from scraps, but in this case, these were made from 20+ year old stair treads. Use what you have!




So I stained the two a General Finishes Warm Cherry (oil based so it won't swell the MDF), and didn't use a clear coat...I liked the flat red finish on the MDF. Then I hung them in the rear of my home theater in whatever pattern floated my boat (and didn't block light switches LOL). If you squint, it sorta looks like a giant Space Invader.





My latest project is a *large* 2D QRD using a great program called QRDude. 2D QRD are often known by the name OmniFuser given to them by RPG. It's supposed to have a 2 dimensional scattering effect vs the single splayed effect from your typical 1D diffuser like my space invader above.

Here is the prototype I made as sort of a "proof that I can do it".




This was after the large, Prime 29 version broke during assembly. Apparently, 1/8" MDF isn't that strong in general, let alone when you cut big comb like slots into it.


The borked one.




After working out some bugs, and going through not one, but two different revisions, I'm well on my way to making a pair of 34" wide, Prime 29 2D diffuser, using 841 little 1" tiles...EACH!


Version 1 - Uncompleted and Retired




Version 2 - Being Built this week!




I don't have photos of the progress yet, because I'm very focused on these Prime 29 I'm trying to build...but a side project that popped up while cleaning up my workshop. Long story short, I built a Maelstrom-X 21" sealed subwoofer for the home theater, and I have all these cutouts from the massive internal bracing I built into the box:





I'm trying to figure out what I'm going to do with all these 3/4" thick scrap panels that look like airline windows....Well, while looking for some scraps for a jig, I started cutting these windows up into 3/4" X 3/4" strips...then I realized, I have all the parts I need for a small "Skyline" type diffuser. And so starts the planning for another fun project!

Ultimately, I'm going to finish up these two Prime 29 (also called N29) 2D diffusers and hang them under my side/rear speakers. Then I think I'm going to build up a couple 2' X 2' skyline and a whole fleet of 2' X 2' 2D diffusers, probably based on Prime 11 (N11) to keep them much more simple then my monstrous N29 diffusers. And on my backwall of the theater, I'd like to upgrade to some deeper (and lighter) 1D or 2D diffusers that would effect the waves coming from the LCR speakers better.

Oh! I almost forgot. I'm also playing around with these "3D Wallpaper" I picked up online. They are designed by an artist, not an audio-guru, but they do appear to scatter sound quite well. I had a nasty flutter echo between my two side/rear speakers (where the N29 will eventually go), and these broke up the reflections enough that the sound from the rear speakers is now MUCH more clear. I'm really surprised in fact how clear the rear speakers are...and I was thinking about replacing them...










OK, enough of my Jibber Jabber...show me some of your favorite diffuser work!!

Last edited by Lonely Raven; 01-13-10 at 09:33 AM.
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post #2 of 23 Old 01-13-10, 11:22 AM
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Re: Show us your diffusers!!

Who knew that the secret ingredient in that "3D Wallpaper" was catnip.
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post #3 of 23 Old 01-14-10, 12:24 PM
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Re: Show us your diffusers!!

More Details on 3d wallpaper please. Looks interesting.
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post #4 of 23 Old 01-14-10, 01:07 PM Thread Starter
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Re: Show us your diffusers!!

Quote:
eugovector wrote: View Post
More Details on 3d wallpaper please. Looks interesting.
A little expensive for what it is, but it does look neat. I'm not sure how they measure. Since it's a recycled paper, and they apparently mold it using a bit of water, it does smell a little bit. But then, I apparently have a super nose.

http://www.mioculture.com/store/pc/v...=2&pageStyle=H
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post #5 of 23 Old 01-15-10, 12:17 PM
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Re: Show us your diffusers!!

Well, cool design. If it was designed for diffusion at that price, it would be a good deal.
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post #6 of 23 Old 01-15-10, 01:32 PM Thread Starter
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Re: Show us your diffusers!!

Quote:
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Well, cool design. If it was designed for diffusion at that price, it would be a good deal.
Designed by an artist, not an acoustician. But that doesn't mean it can't scatter....

I know someone who has a measurement facility...I could send him a set for measurements...but I'd have to pay him for his time. If enough people wanted to chip in $10 each, I'd do all the footwork and post the results online. I can E-mail him and see what his off the cuff thoughts are, and if it's worth bothering to measure them.
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post #7 of 23 Old 01-15-10, 09:03 PM
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Re: Show us your diffusers!!

I found that 3D wallpaper online a few weeks back and ordered 2 boxes (12 per box, 24 total). They appear to be basically the same material as those old-time grayish cardboard egg cartons were made from, just slightly thicker and tan... I'm sure the processing method is exactly the same... my guess is it probably actually costs around a 25 to 30-cents apiece to produce, the rest is mark-up (that's about 1200%... a tasty profit margin for sure). Because my theater is in shades of black and burgundy, I chose to brush paint them flat-black using a water-based latex... just one coat does the trick. The water base paint made them warp toward the painted side when dried but its easy enough to bend them back later. After a trial mounting and trying various noisemaking (clapping, speaking, etc) I determined it would be better to fill the back cavities and chose to use polyfill (pillow stuffing) and double stick tape to attach to the ceiling. Several fell off the next day, so I used drywall screws at the corners... needless to say, they haven't budged since. I mounted 4 of them on a rear wall in the back and the rest of them I attached to the ceiling all toward the back of the theater. You can hear a definite difference when speaking within 18" in front of them and moving from side to side... further back its all the same so my guess is you need to be at least 2 feet from them in order to get any diffusion effect. I haven't taken any measurements yet since they were installed... problem is I've since also installed more broadband panel traps up front so it might confound any comparisons to my last measurements. If nothing else, they look kinda neat... the wife is impressed.

Last edited by monomer; 01-16-10 at 12:36 AM.
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post #8 of 23 Old 01-17-10, 12:36 AM
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Re: Show us your diffusers!!

In keeping with the spirit of this thread, here are some pix taken of our basement theater tonight. A large ~3'X5' QRD 'tune' for 350Hz-4500Hz sits at the back of the room... its a big son-of-a-gun, thing weighs about 160lbs at least... its 9-1/2 feet from the back row of seats, so theoretically its far enough away to work. I will probably paint it black or burgundy sometime soon, just haven't yet decided on the color. The 3D wallpaper diffusers are on the ceiling and near the back door. Normally we have burgundy sheets over the couches but they were in the washer tonight so we just put some lighter colored sheets on for an evening watching movies with the doggies. Projector and lights were on at the time I took these shots.
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Last edited by monomer; 01-17-10 at 01:23 AM.
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post #9 of 23 Old 01-17-10, 01:15 AM Thread Starter
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Re: Show us your diffusers!!

I LOVE the setup! The room looks like a starship with all that up there!

How deep is the QRD on the back wall? And how do you feel it sounds?
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post #10 of 23 Old 01-17-10, 01:35 AM
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Re: Show us your diffusers!!

Thanks... it doesn't look that crazy in reality, its just the lights (wall sconces, lamps, LED over-heads) plus camera flash brings out the contrast between the blacks and grays, but under normal lighting all the black/gray stuff disappears and the burgundy is really dark and offers some dark accents to what would otherwise just be a black cave.... we actually watch movies in total darkness, except for the glow of the screen on our faces. QRD... If I remember correctly it was around 8" deep. I'm not much of a craftsman, so it took me about 12-hours and $80 (I already had some lumber laying around)... what I didn't plan for was the total weight of the thing. Somehow I neglected to calculate that until it was time to bring it in from the garage into the basement... it was a pain and at one point it about fell on me and almost killed me. To be honest, I took before and after REW measurements... the goal was to reduce combing... but naw, didn't really seem to do much to reduce the HF combing, however I'm sure it was better than if I'd simply installed even more broadband absorption. I've been following your threads on DIY diffusers and that's what inspired me to attempt to make one... its also what sent me out to find that 3D wallpaper (the pix you posted in another thread). In general, the room sounds great when you consider its a basement with 3 concrete block walls and a poured concrete slab floor. Thanks for documenting your woodworking projects, its been inspiring...

Last edited by monomer; 01-17-10 at 11:39 AM.
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