or Connect
AVS › AVS Forum › Audio › DIY Speakers and Subs › DIY Sound Diffusers
New Posts  All Forums:Forum Nav:

DIY Sound Diffusers - Page 10

post #271 of 310
This is a great thread! Too bad that no designs came out of this for Erich to mass produce.

I personally would be very interested in Binary Amplitude Diffuser boards that could be used over existing acoustic panels.



1D QRD flat packs along the lines what Decaware offers would also be nice. Perhaps foam could be used instead of the wood to fill the wells like localhosts127 and Perry R did .







I know that Erich is still open to working on this. But he needs solid plans.

Can we give it another try?
Edited by zheka - 4/26/13 at 9:00am
post #272 of 310
What would the cost be for a DIY or group buy type diffuser ?
post #273 of 310
Quote:
Originally Posted by Perry R View Post

Dont know if this will interest you guys or not. For what its worth this is how I made my diffuser.

I work with styrofoam in the stucco trade, and have access to a table wire hot knife, so cutting was easy for me, but with patience it can be done with a hand held unit as others here have done. Table saw works well also.

Instead of blue SM type foam I used white popcorn style, the reason for this is that thin set mortar can be mixed and applied and will adhere very well. Simply mix the mortar to a thin consistency and apply with a paint brush. Once dry it forms a nice hard surface.

For bonding the pieces of foam together and to the backer board...1/8" hardy board in my case....simply use spray foam in a can. This produces a great bond....almost impossible to rip apart. Just make sure that when you put them together you rub the pieces back and forth to break the expansion of the can foam.

After the thinset has dried you can paint any color you wish.


I built it in my living room over the course of 3 days, about 3 hrs a day.


A few pics of my build......total weight about 40 pounds, but thats because of the pre finished shelving used to finish the top and bottom.

















Awesome!! I made some about 20 yrs ago out of thin plywood and used plexiglass for the deviders. I def like your idea much better and might try it when I get to building my own HT if you don't mind of course.
post #274 of 310
Quote:
Originally Posted by zheka View Post

I personally would be very interested in Binary Amplitude Diffuser boards that could be used over existing acoustic panels.

Does anyone have a CAD file for one of these they can share....save me a few hours stuffing around
post #275 of 310
post #276 of 310
I keep re-stumbling into this thread. I can't believe we have so many knowledgeable people and not one marketable design came out of it...just everyone showing off their DIY. Nothing wrong with showing off, but it didn't help this thread come to fruition.

Maybe if Erich has time we can revisit this and come up with something usable?
post #277 of 310
Just out of curiosity, where do you guys recommend that diffusers go? I am currently waiting on my OC703 order to come in, and I plan to make several 2' by 4' panels that are 4" thick with a 4" air gap for the side wall & ceiling first reflection points, then several 2' by 4' panels that will have identical 4" thick OC703 with a 4" air gap for the front wall. I can't decide if I want to use the same panels on the rear wall, or add diffusion to the rear wall.

How does my plan look to you guys? Is that too much absorbing panels? Would you recommend using diffusion on the rear wall in leu of absorbing?
post #278 of 310
Quote:
Originally Posted by Martycool007 View Post

Just out of curiosity, where do you guys recommend that diffusers go? I am currently waiting on my OC703 order to come in, and I plan to make several 2' by 4' panels that are 4" thick with a 4" air gap for the side wall & ceiling first reflection points, then several 2' by 4' panels that will have identical 4" thick OC703 with a 4" air gap for the front wall. I can't decide if I want to use the same panels on the rear wall, or add diffusion to the rear wall.

How does my plan look to you guys? Is that too much absorbing panels? Would you recommend using diffusion on the rear wall in leu of absorbing?

Hopefully Local Host will chime in as he seems to have the Science down well.

But typically, 1D diffusers at the first reflection points (side walls) and especially on the back wall. If it's for two channel listening I will absolutely put a nice big diffuser on the wall between the speakers.

Absorbers on parallel walls and in corners. I also like 2D QRD diffusers on the ceiling to make a smaller room seem taller, I've had that 5ms bounce on the ceiling do weird things to the sound stage in 2 channel listening.

This is all very, very general and measurements and some moving/testing will really help you fine tune your particular room.
post #279 of 310
Quote:
Originally Posted by Elill View Post

Does anyone have a CAD file for one of these they can share....save me a few hours stuffing around

Perhaps this can be helpful

http://www.gearslutz.com/board/9251944-post105.html


a spreadsheet for designing your own

http://www.gearslutz.com/board/6911715-post69.html
post #280 of 310
Quote:
Originally Posted by Lonely Raven View Post

Hopefully Local Host will chime in as he seems to have the Science down well.

But typically, 1D diffusers at the first reflection points (side walls) and especially on the back wall. If it's for two channel listening I will absolutely put a nice big diffuser on the wall between the speakers.

Absorbers on parallel walls and in corners. I also like 2D QRD diffusers on the ceiling to make a smaller room seem taller, I've had that 5ms bounce on the ceiling do weird things to the sound stage in 2 channel listening.

This is all very, very general and measurements and some moving/testing will really help you fine tune your particular room.

I have spoken with Localhost several times, but it has been at least a year or two ago since I last picked his brain and I have learned a lot since then.

I think that my absorbing panels (made out of 2'"OC703 stacked to make each panel 4") will be hung on the side walls at the first redlection points, and on the ceiling at the first reflection point up there, and on the front wall behind the speaker.

I plan to use some of the pink fluffy stuff in the corners, cut into triangles and stacked on top of each other with some netting used for support.

I would really like to use some diffusers on the rear wall, but they are so expensive! I would love to build my own diffusers but I honestly have no idea on how to do that as my knowledge on diffusers is extremely limited.
post #281 of 310
Quote:
Originally Posted by Martycool007 View Post

I have spoken with Localhost several times, but it has been at least a year or two ago since I last picked his brain and I have learned a lot since then.

I think that my absorbing panels (made out of 2'"OC703 stacked to make each panel 4") will be hung on the side walls at the first redlection points, and on the ceiling at the first reflection point up there, and on the front wall behind the speaker.

I plan to use some of the pink fluffy stuff in the corners, cut into triangles and stacked on top of each other with some netting used for support.

I would really like to use some diffusers on the rear wall, but they are so expensive! I would love to build my own diffusers but I honestly have no idea on how to do that as my knowledge on diffusers is extremely limited.

Yeah, I like the enveloping sound of diffusers, so I tend to wrap the room in them if I can...and since I dabble in woodworking, I have no problems spending $100 to make 4 goodly sized diffusers.

With QRDude http://www.subwoofer-builder.com/qrdude.htm You can design whatever you want, or whatever will fit the space you have. Between that program and LocalHost's advice in this thread anyone could get a good leap ahead of where they were.

Decware also has diffuser plans that I've used in the past. These current ones are great for smaller rooms that need some break-up and don't have the 15' of space between listener and diffuser http://www.decware.com/p1312.htm

I believe they still sell flat packs of those diffusers, though I've not looked into it since I can build my own. Hmm, looking at the Decware plans, those are not 24"X 24" - I swear they had plans for the larger 24 X 24 ones which would be preferable IMHO.
post #282 of 310
Those DIY plans look interesting. I have not tried the QRD simulator, but I would imagine that it is pretty tough to use for someone that had little to no knowledge with regards to diffusers. I might try to start reading up on how to build or design diffusers. Do you or anyone else have any suggestions? I already have ample absorbing panels that I built myself, and I have a decent understanding of small room acoustics.
post #283 of 310
Quote:
Originally Posted by Martycool007 View Post

Those DIY plans look interesting. I have not tried the QRD simulator, but I would imagine that it is pretty tough to use for someone that had little to no knowledge with regards to diffusers. I might try to start reading up on how to build or design diffusers. Do you or anyone else have any suggestions? I already have ample absorbing panels that I built myself, and I have a decent understanding of small room acoustics.

Read all of the QRDude help pages online... ALL of them. It's actually fairly simple. Just use a reflective material (like extruded polystyrene painted, wood, plaster, metal, anything solid will work). Remember that you have to use dividers if you want to be sure it functions as designed, unless you are willing to either get deep into this or are OK with taking a shot in the dark as far as function (with the knowledge that you may or may not be able to tell the difference between something an acoustician would call "properly functioning" from something not, depending on your acoustic measuring chops). Also, remember that you can't just place multiple copies of the same thing side-by-side and expect the whole assembly to work as expected. Basically, repetition of any shape causes effects you don't want--I think the QRDude page talks about using the inverse panels to make arrays that continue to function as expected.

For some good finless designs, and some things that will give you an idea what it would take to make a finless design work (extensive simulation), you can check out http://arqen.com/sound-diffusers/
post #284 of 310
Quote:
Originally Posted by aackthpt View Post

Read all of the QRDude help pages online... ALL of them. It's actually fairly simple. Just use a reflective material (like extruded polystyrene painted, wood, plaster, metal, anything solid will work). Remember that you have to use dividers if you want to be sure it functions as designed, unless you are willing to either get deep into this or are OK with taking a shot in the dark as far as function (with the knowledge that you may or may not be able to tell the difference between something an acoustician would call "properly functioning" from something not, depending on your acoustic measuring chops). Also, remember that you can't just place multiple copies of the same thing side-by-side and expect the whole assembly to work as expected. Basically, repetition of any shape causes effects you don't want--I think the QRDude page talks about using the inverse panels to make arrays that continue to function as expected.

For some good finless designs, and some things that will give you an idea what it would take to make a finless design work (extensive simulation), you can check out http://arqen.com/sound-diffusers/

If the 3d printers were cheaper... This might be a good way to build some.
post #285 of 310
Quote:
Originally Posted by ellisr63 View Post

If the 3d printers were cheaper... This might be a good way to build some.

I feel a grumpy cat image macro coming on. There are good reasons for this, but for the moment I will just say...
LOL. No.

Hmm, that kinda felt like BF, too. Maybe Bill Fitz is really grumpy cat. Or vice versa. LOL.
post #286 of 310
Quote:
Originally Posted by ellisr63 View Post

If the 3d printers were cheaper... This might be a good way to build some.

Would be expensive, as a large envelope wuld be required (big, expensive machine) and he cost of 3D printing is proportional to the volume of material used.

Though re the latter I guess you could print a "skin" and fill it with plaster or expanding foam.
post #287 of 310
Post removed (double facepalm image macro) due to the post it responded to having been deleted.
Edited by aackthpt - 10/14/13 at 6:06am
post #288 of 310
Aaaaaand the thread is dead again.


I'll see if I can drum up a decent design and see if Eric still has time and connections to get a quote on flat packs. I'm going to be needing a design for myself anyways, so I might as well work on this one simultaneously
post #289 of 310
I've made my own absorbsion panels.... need some diffusion.

This gentlemen seems to know a thing or two about acoustics:


Source: http://www.avsforum.com/t/1494052/acoustics-101-with-anthony-grimani/0_100

Styrofoam diffusion panels in line with Anthony's "recipe" (@ 18:47 in the above video) would be AWESOME!

@ 28:32:



@ 30:38:


So basically 3D diffusion and some other horizontal/vertical dispersion panels. I am maybe 5% of the knowledge base in this thread, hence my reference to such a fundamentally layman reference. That said, I do believe establishing something like this as a starting point would be really good for the majority of DIY enthusiasts...

My $.02.
post #290 of 310
Would also be very very cool (if any of this came to fruition) if wall/ceiling mounting brackets were included with the panels.
post #291 of 310
Grimani is great.

Diffusion is fine (a room ideally suited for it, there's nothing like it), however there are minimum distances needed for implementing diffusion properly.

Typically, the recommendation is that the listening position is 3x the wavelength of the lowest frequency diffused. Many go ahead and install it anyway to mixed results.

Where do you want to employ diffusion?


Oftentimes, in small rooms such as yours, absorption rules the day. When the listeners are relatively close, the rear wall behind the listeners can benefit from massive absorption. This smoothes the complex comb filtering and 1/4 interferences that can rob a system of punch, mid-bass detail.
post #292 of 310
Quote:
Originally Posted by popalock View Post


This gentlemen seems to know a thing or two about acoustics:
Maybe he does, but his advice isn't particular good. Just some broad general ideas for people who don't want to learn how to treat a room specifically and understand psycoacoustics. Saying that surfaces should be 20% absorbed and about 25% diffused is really meaningless. Unless you're selling such products and earn money on it...... You first decide the concept and goal and then treat accordingly.

Localhost's writing and advices in this thread is far better.
post #293 of 310
Wouldn't this work... Make your whole room absorb and then place diffusers where you want to have reflections?
post #294 of 310
Quote:
Originally Posted by popalock View Post

I've made my own absorbsion panels.... need some diffusion.

This gentlemen seems to know a thing or two about acoustics:


Source: http://www.avsforum.com/t/1494052/acoustics-101-with-anthony-grimani/0_100

Styrofoam diffusion panels in line with Anthony's "recipe" (@ 18:47 in the above video) would be AWESOME!

@ 28:32:



@ 30:38:


So basically 3D diffusion and some other horizontal/vertical dispersion panels. I am maybe 5% of the knowledge base in this thread, hence my reference to such a fundamentally layman reference. That said, I do believe establishing something like this as a starting point would be really good for the majority of DIY enthusiasts...

My $.02.


all those panels are fine with those speakers.

alternatively, two of these do just as good in many ways and better in others.



just say'n. :-)~
post #295 of 310
it is actually kind of strange, but the panels that would probably help the average person the most (once using waveguides) would be on the wall right behind the speakers and that is about the only place in the whole room where there is nothing.
post #296 of 310
Quote:
Originally Posted by LTD02 View Post

it is actually kind of strange, but the panels that would probably help the average person the most (once using waveguides) would be on the wall right behind the speakers and that is about the only place in the whole room where there is nothing.
Explain to us why please. We're after all not talking about dipoles, but speakers that have a baffle/horn.
post #297 of 310
at 80-240hz or so, sound is highly omnidirectional.

at 1/4 wavelength to boundaries, destructive interferences occur.

most people position their speaker such that they are 1-3.5 feet from the front wall.

this is the distance that will create destructive interferences in the 80-240hz zone depending on particular distance.

it is more of a midbass cancellation problem than a first reflections/imaging problem that the horns solve quite well.
post #298 of 310
Quote:
Originally Posted by popalock View Post

This gentlemen seems to know a thing or two about acoustics:



If you look at the left and right sides of the diagrams, you'll notice that the treatments aren't symmetrical. Where he has a diffuser on one side he has absorption on the other and vice-versa.

I've tried this and, as anyone would guess, it resulted in an asymmetrical soundstage. If that doesn't bother you, then follow his advice, but the imbalance drove me up the wall.
post #299 of 310
Quote:
Originally Posted by LTD02 View Post

at 80-240hz or so, sound is highly omnidirectional.at 1/4 wavelength to boundaries, destructive interferences occur.most people position their speaker such that they are 1-3.5 feet from the front wall.this is the distance that will create destructive interferences in the 80-240hz zone depending on particular distance.it is more of a midbass cancellation problem than a first reflections/imaging problem that the horns solve quite well.

For others, this is classic SBIR, google it for examples and visual explain.
(Speaker boundary interference response)

Simply, your driver center should not be at same distance from a boundary if possible. Think Height from floor, from side wall, from front wall.
I actually moved my floor standing speakers closer to front wall to improve my SBIR.



Via my 32GB iPhone4 using Tapatalk
post #300 of 310
I love all of the talk about diffusers, absorbers, etc., but, where does a person find acoustically transparent fabric that is printed with art?

I need to make some absorbers for the theater room, so solid colors are fine, but I am also redoing my living room décor. With hardwood floors and flat ceilings, I need something to help absorb sound and look good. I can find a lot of pre-built panels that range in the $300-450 range (ouch!), but I want just the cloth, rolled up in a tube, so I can make my own absorbers.
New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: DIY Speakers and Subs
AVS › AVS Forum › Audio › DIY Speakers and Subs › DIY Sound Diffusers