Questions about diffusers

Hi all, a few question concerning diffusers and their design. Since the only book I could find elaborating on the subject is over 140 euros, I figured I 'd ask here first: 1) In the case of a QRD diffuser, do I have the design principles right? _Wavelength of lowest freq affected = 2x depth of deepest well _wavelength of highest freq affected = 2x total width of a single well _smoothness of diffusion increases with number of well depth variations 2) Does a diffuser need to be solid? two sketchup drawings as a reference to what I'm thinking about. Less material, lower construction cost. So I figured I'd pop the question. 3) Is there a minimum width to a diffuser well? I can imagine that, at some point, making a well too narrow would make it into a resilient obstacle for sound waves wanting to enter the diffuser. 4) I understand there's an upper limit to the width a diffuser should have. Exceeding this maximum would reduce effectiveness of the diffuser design. The details on this are very unclear to me. Could anyone elaborate on this? That's all I have for now. :) Sigert

*polite bump*

I'd make them solid or atleast put some wool innit (to prevent drumskin noise)

I said a lot about diffusers on the studiotits forum but humble, nice, helpfull Ethan has taken it down. :D

studiotits? whow.

Beats the standard lavalamp. Anything from your studiotips thread, related to my 4 initial questions, you would care to share with us? I'm fascinated by them and am really trying to grasp their design principles.

I'm fascinated by them and am really trying to grasp their design principles.

Me too. (I hope we're still talking about studiotits.)

Ask Ethan Wanker to let go his firm grip on the balls of Dan Nelson and get the studiotits site online, and I'll tell you all. I'm of course the leading authorataaaah on numerical diffuser design because I read the books by Manfred Schroeder AND understood 'm. :D I also have a nice bunch of real life measurements on diffusers I want to share with you, but no chance as long as Ethan is playing asswipe.

Hey Bert, Do you have any opinion on utilizing diffusion in smaller rooms? Like 12x15x7' rooms (3.5x4.5x2m)?

Mmazurek: I don't think diffusers would be main point of concern/consideration when it comes to smaller rooms. I wanna try them out anyway though. Hence, if I could get those 4 initial questions answered, I could build some and find out. Bert: If you have a problem with Ethan Winer, talk to Ethan Winer. Let the forum be for facts. Should you care to share those facts with us, it would be greatly appreciated, I'm sure.

MMazurek wrote:

Do you have any opinion on utilizing diffusion in smaller rooms? Like 12x15x7' rooms (3.5x4.5x2m)?

I made a video demonstrating something similar, showing how diffusion sounds when it's very close to a microphone or sound source. The demo was made in my fairly large home studio, but the principle is the same as using diffusion in a smaller room. You'll find this video near the bottom of the page here: http://www.realtraps.com/videos.htm --Ethan

I'm not the only one with a problem. Ethan closed a scientific forum with over 2000 members. Ethan doesn't want to talk. He has lawyers for that. And you all look the other way. Thanks for that.

Hey Ethan, I've already seen/heard the video and appreciate it. I wonder if the effect the diffusor is having (both near & far) is partly due to the absorbtion qualities of your specific diffusor. I really like listening to more diffuse spaces for the 'non-boxy' quality, but feel that your example shows off the low-mid absorbtion more than the diffusion. I really feel the dip in the 400-600hz range.

MMazurek wrote:

I wonder if the effect the diffusor is having (both near & far) is partly due to the absorbtion qualities of your specific diffusor.

Possibly, and that's why we also did the same test with pure absorption, which you can hear sounds very different from the diffusion. Again, the point of the demo is to exaggerate the effect of what diffusion sounds like close up, to make it easier to hear. I'm not recommending that you put a microphone or guitar 6 inches from any diffusor. :) --Ethan

The best information on diffusers can be found here: http://forum.studiotips.com/viewforum.php?f=1 Cheers,

Big8: The Studiotips forum is offline. What's the 2nd best source? :)

Ask Ethan, he knows. :D

Sigert wrote:

Big8: The Studiotips forum is offline. What's the 2nd best source? :)

Sigert, for diffusers, there isn't a 2nd best source, except for very expensive books. cheers,

Sigert wrote:

What's the 2nd best source?

The best free source, and one of the best sources regardless of price is the BBC RD 1990-15 report. It has a fair amount of math, but is very comprehensive. Andre

Oh, yes, I forgot that paper Andre, excellent! :D I feel 1/2 homeless without Studiotits :evil: Cheers,

The BBC RD 1990/15 document states the following: Page 3, chapter 4.1 - "... They [diffusers] are usually heavy and expensive. In some cases, there may also be excess acoustic absorption and other problems because of the inherent resonances of the large areas of poorly restrained and relatively non-rigid wooden panels." -> could this imply that diffusers need to be solid objects? Big8: if you send me your address, I'll send you a pair for christmas.

Thanks sigert, but my room sounds really good already without any kind of added diffusion. What I really need right now is to have STUDIOTIPS FORUM BACK ON LINE!!!! Cheers,

I have had to bring it back online enough to search through it, however you guys keep finding it so I have hidden the discussion area from the public to allow me to continue with the search. I also have to find long term solution to protect the collection of knowledge in the forum. The bigger problem is how to keep the forum going after I'm gone, without it becoming an Ivory Tower. The goal is to have something with academic knowledge that comes form organizations like AES and ASA with deep practical as well as academic knowledge of an organization like SynAudCon, yet accessible to everyone with an interest. Plus able to continue indefinitely, I would like to leave the forum enough money in some type of endowment to keep it going till that ongoing body of knowledge is no longer needed. I have thought of upgrading the forum to the new version during this down time however I was already overloaded with work and life before this came up. Then after all that, dealing with bloody spammers even off line some of the spambots manage to sign up. One day I wil figure out how to disable the signup page yet still allow the admin to add members manually. Dan Nelson

Thanks for the update, Dan. Take care and let us know if you need any help :shock: (putting on my battle costume) Cheers,

Thanks for the update too Dan. Writing poor grammar, Andre