DIY Omnifusor/Bookshelf

[audio[LAB]]

We are in bad need of some acoustic treatment in our newly setup control room. The room Is actually a 2 car garage with an 8ft ceiling. I figured I'd start with an omnifusor In the back wall facing the monitors.

I saw this pic on a kids Myspace. Its at Q Division Studios in Boston:



I figured I'd put some insulation between the wall and the shelves. Ikea sells these expedit shelves that will work great:




I'm just going cut it around so the shelves aren't so symetrical.

As far as the acoustics go, i'm going to fill it with a ton of books and leave some empty with boards angleing inward. Its really a shot in the dark though. I'm just going off of the pictures I've seen of real omnifusors.

Suggestions?

[Smitty]

ethan chimed up on a thread i started a while back and kinda bursted my "book treatment" bubble. FYI.

[JWL]

Yeah, what you describe is not diffusion. Diffusion is a calculated phenomenon, it is not just simple scattering. It is scattering at particular frequencies, uniformly throughout a given dimension.

I think you'd get better results just from building simple absorbers for the rear wall. If you really want diffusors, I'd go with a proven commercial design. I believe someone sells a kit for building a QRD diffusor, though I can't recall who sells it or how much they are.

For more on room treatments, check out some of Ethan's articles:

http://realtraps.com/facts.htm
http://realtraps.com/art_room-setup.htm
http://realtraps.com/rfz.htm

[audio[LAB]]

AAAAHHHH but it looks so awesome! How about some kind of combination of the real thing and a bookshelf? I know I know I'm just being stubborn. I guess I'm just trying to do something a bit different. I don't really like the way typical acoustic treatment looks.

Anyone have any other suggestions on obscure cool looking acoustic solutions?

[norton]

- Diffusion is a calculated phenomenon -

true.


BUT anything with a 3 dimensional shape will diffuse sound. Some shapes and sizes do it better than others but the bottom line is that your idea WILL work, and if you get the right materials and do a little research, it'll work WELL.
Especially taking into consideration the relatively large area it occupies.

Read up on RPG diffusers, and adapt that info to your bookshelves. It may not be perfect or ideal.. but if you've got some problems in the space... you'll be better off doing something than nothing.

Keep in mind that in order to be effective at breaking up and scattering specific frequencies, you'll want to at least have 1/4 of the the wavelength in depth or relief.

And the smaller the space - the more low end trapping you'll need. You almost can't have enough. Look for unused space to put traps.... like under your console... ( this dead space is a HUGE low frequency factory) closets.... all your 90 degree corners... YES even the ones at the ceiling.

go for it! and then come back tell us how it totally worked... tightened up the bass, gave you way better stereo imaging and only cost you like $150 for like 60 sq feet of pretty kickin bass trappin diffusion. Because that's what's going to happen if you do it right.

Good luck man!

dig

zack

[JWL]

Norton, you are describing scattering. Diffusion is a subset of scattering, with very specific techniques to make it happen. Anything with a 3D shape will NOT diffuse sound necessarily, but it is likely to scatter sound to some degree. Again, diffusion is a special type of scattering, in which sound energy is scattered equally in all directions.

audiolab, if that's what you want to build I say go for it. Even if it's not diffusion in the true sense of the word, it is likely to improve your sound if you build it right. One possibility: put some broadband absorption on the rear wall, cover with cloth, then put your shelf in front of that. So if you do get some diffusion, great; if not you are still getting some absorption back there.

[norton]

At this point JWL...i think we're talking about scattering semantic heirs.

I should have chosen my words more carefully... (diffuse as the verb - to scatter or disperse - as opposed to diffusion -the technical term of art)... and should have used the phrase
"any 3 dimensional shape will move sound around"...
which is what i meant. sorry for being so muddy.

In any envent.... I say - GO with the 703 - bookshelf and buy yourself a pair of 500 series preamps with the money you save. The scattering box will get you damn near 85% of the way there and the new pre's or eq's will make up the difference in a ridiculously substantial way.

good luck..

[audio[LAB]]

This is exactly what I wanted to hear. Its a fairly big space for a control room and this isn't the only treatment the room is going to get. I'm going to spend a good amount of time reading up on diffusion in order to work it in with my idea (not really MY idea but ehh).

I guess I don't want to admit the fact that I care more about aesthetics when it comes to acoustics mainly because of my ignorance toward it. I figure if I'm going to spend 13 hours in a room at a time it better be comfortable and have a good feel. The relaxation a comfortable room can give me is almost as important to my state of mind as the sound. I've been in rooms that have the cheap looking auralex stuff on the walls that sound good but make me feel like I'm in a padded room at a mental hospital, if that makes any sense.

Thanks guys!

[Babaluma]

i put that exact ikea shelf on the back wall of my tiny studio in japan, and it really tightened up the bass! i say give it a go!

[roscoenyc]

here's the decware diffusor kit.
also sold built.


http://www.decware.com/newsite/mainmenu.htm

click on 'rooms' should get you there
they don't go way down but I got a bunch of 'em and like what they did to our room

[JWL]

thanks, roscoenyc. That's the kit I was trying to remember.

[roscoenyc]

thanks, roscoenyc. That's the kit I was trying to remember.

Sure thing. Those people were cool to deal with.