understanding reverb in different shape rooms

hey there.... i had a few questions that I think fit into this area of the forums..... basically I am trying to understand reverb and how that plays into a studio room I am going to be building. The room is going to be used as a one room studio and I am basing it off of wes Lachots design for a one room studio. http://www.overdublane.com/wes/database/pagemaker.cgi?1106083441 Anyway I am hoping to get a room that is usable for mixing in but also sounds great to play acoustic guitar in. I understand that non parallel walls will help stop standing waves from developing, but do they also kill reverb? the question is.... if i had a room that was 13' x 21' x 8' and generally the shape of a shoe box .... would that room have more reverb than a room built around the same average dimensions but without parallel walls/ceiling/floor???? I hope that question makes sense... I guess I am trying to see if the wes lachot trapezoid room shape will sound better than a box shape room as far as reverb .... or does the trapezoid shape kill the sound of a room and make it naturally deader...???? thanks a bunch and look forward to your responses!

No, the shape of the room will not "kill reverb" per se. What it will do is greatly reduce/eliminate "flutter echo" which you definitely don't want to hear while playing or in your recordings. What affects reverb is the construction details of the room, and of course the size of the room. Think of it this way, in a perfectly sealed, perfectly reflective room (hypothetically speaking) sound will bounce around the room, slowly losing energy until it dies away. If the room is not airtight, then some sound will escape out of the room. If there is absorption in the room, then much of the sound will be absorbed as it bounces. Diffusion is another way to affect how the sound moves about the room. Wall shape won't really affect this much, it will just affect WHERE the sound goes when it bounces. In a well-designed room, you can use this to your advantage not only to kill flutter echo, but also to create a Reflection-Free Zone to get rid of first reflections, which when listening to stereo speakers tightens up the stereo image.

JWL thanks for the speedy response and the clarification. I searched all over a buncha resources and never got a clear answer on that. My last question about this is... When a room is designed in a trapezoid shape with this type of treatment would a warm sound tend to collect at the rear center of the room leaving a fairly decent RFZ for the mixing position?

Let me put it this way: I wish I had the luxury of recording in a Wes Lachot-design room. ;-) I'm sure the room will sound great. That said, I'd do the acoustics a bit diffently than how he does it; rather than "bass traps" (these are really more accurately called "broadband absorbers") lined near the corners, I'd put superchunks in the corners. I'd probably use John's slot resonators (possibly angled) along the side walls for RFZ creation, and I'd probably go with absorption on the back wall rather than diffusion. But other than that, I think it's a very intelligently designed room.... To answer your question, I think the specifics of where sound will "collect" will be frequency dependent. For example, bass usually tends to accumulate in corners. But seriously. Don't worry about that. If you have the resources to build this room, I'm sure you'll be stoked. JWL PS- I used to live in Columbus, back when I was pretending to be a student at OSU.... from 1988-1992 or so.... LOL. I grew up in Cincinnati, so I'm an old Ohio boy....

well in that case... .GO BUCKS!!! thanks for your advice again JWL ..... I was planning to superchunk the corners and put a bookshelf on the back wall... but if you think absorbing is the best idea back there I might try it with gobos and see how it works out... thanks agian! h0bo4life

That length room is on the edge of being long enough for diffusion at the rear instead of absorption - if you're gonna record in there, might wanna consider diffusion. You can always put 3 or 4" rockwool over the back wall if you don't like it, or build some portable gobo's to switch the acoustics between dry (mix) and not-so-dry (track) Just a thought... Steve

I agree that gobos on the back wall make sense, especially in a one-room design. When you are recording, you can move the gobos around strategically to maximize isolation in the one-room design. Then when it's time to mix/critically listen, move the gobos to the back wall again so they will absorb rear reflections. Another option is to combine your bookshelf approach with absorption; fill the back wall with absorption of whatever variety you like, and then put bookshelves in front of that. :-) Note that bookshelves aren't necessarily good diffusors, but they should break up reflections a bit.

ya.. ... one of the deals with getting to have this kind of space in our house when we build it is that my wife can use this room as kind of an office type space a little bit of the time and the bookshelf was a tradeoff to make her happy... gobos are easy enough and cheap so i'll probably go ahead and go that route and keep them off to the side or in a closet when i'm not mixing. thanks for all the feedback guys and i don't know what i'd do without your expertise. This forum has reallly helped me out a lot!