Possibly not off topic - tuning a room

[Joe Hart]

We just moved and I'm setting up a studio in the basement. And I'm having issues with bass frequencies bouncing around (concrete floors and walls). I've laid down some carpets and stuff and got rid of some high frequency reflection, but the bass is a problem. All my amps sound incredibly boomy and lack any definition at all. :-(

Does anyone know about bass traps? I am looking into building some of the large plywood panel boxes with rigid fiberglass inside (I don't know what they are officially called). I have build plans and drawings and everything, but would like to know if the actual dimensions of the plywood panel are very important. Everything I read about says 2' X 8' so you can get two panels out of a sheet of plywood. Can I make them 4' X 6'? Or almost any size? I would imagine that different sizes would trap different frequencies, so if I just did a bunch and kind of "covered all the basses" (no pun intended) would that work? I can build them VERY cheap, so cost isn't really an issue.

Any help would be great!! Thanks.
-Joe Hart

[petemoore]

I'd guess you're discussing 'bass traps' as a tuned 'muffler' type thing, allows certain frequency to pass, but the length of the waveform of certain bass frequency range is attenuated by the size and importantly the length of the 'trap'.
 But I'm really not sure what you're talking about 'looks like.
 Boxes can be tuned for somewhat frequency specific bass resonance or attenuation.

[Joe Hart]

It's basically a large piece of 1/4" or 1/8" plywood (different frequencies) mounted to a wall with 1 X 4's, with a sheet of fiberglass inside it to absorb some of the sound waves. And it's all airtight with caulk. So, it's pretty much like framing a plywood wall against the concrete wall. Does this help you "see" what I'm talking about?
-Joe Hart

[Joe Hart]

And I know they can be "tuned" to certain frequencies, but I also think they have a rather wide range to them. So, if it's tuned to 60Hz, it will also get a lot of 50Hz and 70Hz, and some 40Hz and 80Hz, and a bit of 30Hz and 90Hz, etcetera. I was hoping to just kind of throw up a bunch of them and see what happens!?!? If I'm understanding correctly, you really can't have enough bass traps. It will only tighten up the bass response of the room, not eat it all up. Or am I way off track here?
-Joe Hart

[petemoore]

Since you said something about EZ acess to materials, and considering there are only a 'few cuts per unit...I say 'mess with it' [if you are  inclined to do so] also because what you start with obviously influences what you end up with 'after] the tuning bit.

[therecordingart]

Check out www.recording.org and go to the Acoustics and Design section of the site.  They will be happy to help....plenty of acoustics experts there.

[MartyMart]

http://www.soundonsound.com/sos/jul00/articles/faqacoustic.htm

Joe, there's some good info here, from a very good "UK" music tech mag
If you skip through the "basic" stuff, I'm sure that you'll find some good
info on bass traps etc.
Oh BTW - go easy with that carpet, its very easy to make the room much
too "dead" with it IE: you'll soak up way too much hi-mid/top end !!!!
You need a balance of carpet/wood/non flat surfaces etc  :wink:

Marty.

[petemoore]

:gregs; studio room for the drums had carpet strips hanging 12'' down from the ceiling, this absorbed sound amazingly, and too well in IMO...COMpletely DeaD.
 I prefer it very dead around the drummer, and some 'liveness' [at least] elsewhere, otherwise there's no 'room sound' per se'.
 It is possible to 'kill' almsost all room reflextions, but I don't like when the room is so dead.

[Joe Hart]

Am I also correct in thinking that the huge plywood traps work better than the triangle foam corner traps?
-Joe Hart

[sean k]

You could also look into something called a helmholtz resonator.They work somewhat like tuned bass reflex in that air in a chamber is used to absorb bass frequencies.I suppose you've figured out exactly what the room is tuned to,or its resonant frequency so you can make sure of anything you use wil be specific to that.So you'd maybe make a false wall about a foot out from a wall and have ports in it with different sized chambers around each one.

[Connoisseur of Distortion]

my advice for cutting bass from your amp is simple. observe your amp. you will not that there is a pot labeled "Bass". adjust to desired level.  

actually, try getting your amp off the ground. i had a little step-thing i set my amp on to cut its bass response a bit. definately made my baseent experiences passable...

[sean k]

Right,the problem is lessened drastically if you haven't got drums going in there in which case you play pink noise into the room and measure response and you'll get your peaks and dips so you make up an EQ to cut at the peaks...easy.

[Joe Hart]

Thank you Connoisseur of Distortion. I was wondering what all those pretty knobs were for. Just kidding.

The problem is the room itself. Everything is boomy and muddy in the low frequencies. Even a little portable CD player up on a folding chair.

So, I'm just going to go and make some of those big plywood bass traps (I can make them for about $30.00 each, and it may take a weekend to make 6 or so). From what I've read, that should help if not solve the problem.

Thanks everyone! And any other thoughts would be appreciated!!
-Joe Hart