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Discussion Starter #1 (Edited)
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!!
 

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Discussion Starter #6
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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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.
 

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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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Discussion Starter #9
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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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...
 

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Here's some more details on my QRD construction...

I started off knowing the approximate dimensions of the space I wanted to fill and the approx freq range I wanted to target (the deep combing I observed from REW graphs). I decided since I had a number of 2"by4"s and 2"by8"s laying around I wanted the well width to be 1-1/2". So using QRDude and 1-1/2" as a definite well width, I tried plugging in different numbers to get a close match to the freq range and with a total width that would fill the 5 foot space between my rear speakers. Three prime 11 continuous diffusers seemed to fit the space and the 7-1/2" depth seemed to work with the lumber I had on hand... I just needed to rip them down to size for each of the wells. The freq cutoff range for this design was 369Hz-4526Hz and has a minimum seating distance of 9' 2" so I determined it would work in my theater. Next I bought three 3/16" wood paneling (4'by8' sheets), two 1"X8"X10's to frame around the diffuser, a couple 2"X6"s, decking screws, paneling glue and chaulking. Set up a table saw and an chop saw, jigsaw, and a cordless drill and about 12-hours later I was hauling the finished QRD downstairs.
 

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Discussion Starter #12
I've made a little progress on my 2D QRD diffusers I'm building for the rear of my Home Theater.

I've got the "grid" finished for the first one, and I'm starting to glue in the 814 tiles. I still have one more to go.

Yes, I went overboard on this one...but it's one of those "because I can" builds. I'll have more sensible diffusers built up after I get these two monsters done.













I need to sit down this weekend and really make some progress on gluing in the "tiles" at different depths. Otherwise it's going to take me a month (one day per row) to finish this first one up...and I don't want to take that long! I should probably find some fast setting glue as well....
 

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Awesome... wish I had the tools, workshop, time, money, skill, patience, etc. to do something on that scale. How big is that thing? and how heavy do you estimate it will be when you're finished? and how do you intend to mount it? ceiling? Nice work there... can't wait to see it progress to its completion.


Just realized today that the thread of yours I'd been reading was on the other forum (gearslutz). When I tried to register there a couple months ago, I found out someone there was already using my usual name "monomer" (so I had to register there as 'theothermonomer'). I've been using monomer since 1996 and thought it was unique ...until now.
 

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Yeah, I'm not the *only* Lonely Raven on the intarwebs, but I'm the dominant one. I've been using this callsign since about 98. In fact, I actually got a thank you card from MSN for using their E-mail with the same name for 10 years! LOL

As for the big diffuser. It's a Prime 29 (or N29), the tiles are 1" X 1" roughly, and the overall dimensions are about 34" X 34" X 3.5". It currently weighs about 15lbs, but with all the tiles in, I figure it will weigh in about 30 lbs or so. I built it to be light considering many people, for some odd reason, like to build 1D and 2D diffusers with SOLID blocks. Solid blocks are totally unnecessary for the device to scatter as designed.

I plan on replacing the 3D wallpaper with these...in fact, the 3D wallpaper is just a place holder and fun/cheap/easy project to enjoy till I finish with these monster 29X29 diffusers.

Since I have materials and fins left over, I may make some smaller 2' X 2' from the scraps and reject fins and use them on the ceiling. The more I read about acoustic design, the more I'm leaning towards diffuser than absorbers.
 

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Talk about DIY! A month of gluing!

I had planned just to send the plans for the "omnifusor" to the local EPS workshop and they would cut each row, profile it, and even said they could glue all the rows together.
 

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Talk about DIY! A month of gluing!

I had planned just to send the plans for the "omnifusor" to the local EPS workshop and they would cut each row, profile it, and even said they could glue all the rows together.
OH believe me...I'm finding every excuse in the book as to why I can't find time to get into the garage and finish this project up! LOL

Seriously, if you have a shop that can make these affordable, then go for it!

My next set are going to be smaller, easier, and fast to make. :bigsmile:

Seb, make sure you post your diffusers here when you get them done!
 

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Discussion Starter #17
I've been away for a long while...haven't been able to do any work on the house or home theater due to health issues and a small electrical fire (don't trust previous owners wiring!!).

Anyone else have some diffusers to show off, I could use some inspiration!
 

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These diffusers are called Art Diffusers. The default size is 15 inches square, but I built the side ones 12 inches square to match the foam tile. I made them out of ranger board and sprayed them with speckle stone paint. I have 38 units for a total of 5472 blocks that were cut to length. I simply just glued them together and took 45 min. to glue one unit.
 

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