Acoustically treating a closet

[Elvis Christ]

Hello,

I've got a closet that is 4 ft. deep, 33 inches wide, and 9 ft. high with carpet on the floor. I've been wanting to throw a 2 x 12 cab in there and keep it mic'd at all times...that way anytime i want to record guitar, i flip a switch on the amp in my control room and i'm ready to go.
I'm not really concerned with isolation...i mostly just want to treat the closet so that i don't get any strange resonances. I don't need to crank the amp super-loud as I use a solid state Hughes and Kettner Zentera. I figure the closet itself will give me enough isolation to avoid disturbing my roomate and will also keep me from having cables run all over my house.
The materials i have to work with are several 2 x 4 pieces of Auralex pyramid foam (probably enough for the whole closet), several blankets, and I also have access to some 1" thick pressed fiberglass board ("furnace board") with foil backing.
The walls are plaster, so it will be a bit tricky to mount stuff without cracking the plaster.
Before I embark on this project, I just wanted to consult and get an idea of a good direction to go in. Thanks!!!

[Sigma]

make 1x2 "frames" stuff with fiber glass do all walls... put in some corner 1/4 round traps for the boxey 200-400 that will still probably be there..stick a plastic ceiling diffuser up

dead is better in a room that size

[Ethan Winer]

Originally Posted by Elvis Christ

The materials i have to work with are several 2 x 4 pieces of Auralex pyramid foam (probably enough for the whole closet), several blankets, and I also have access to some 1" thick pressed fiberglass board ("furnace board") with foil backing.

Rigid fiberglass is better for bass absorption than thin foam, but you need three to four inches thick. So peel off the backings and stack four pieces adjacent to get enough thickness, then put them straddling corners. More here:

Acoustics FAQ

--Ethan

[Sigma]

ethan if he losses 8 inches width wise at 25 inches he ain't gonna fit much anything in there..

[Elvis Christ]

true. the dimensions of the closet limit what i can do to some extent. although i would love to, i can't just line the entire closet with 4 inches of fiberglass.

[jamsmith]

Try hanging some horse blankets a couple of inches from the walls.

[Old Cane]

That sounds like something i would do. Do you mean saddle blankets or stable blankets?

[Sigma]

you know dude i was just thinking....when ya put an amp in therre angle it toward the ceiling.. then you can mic the cab and a little further off ..plus you got over 8 foot of breathing space rather than less than 4

just a thought

[Elvis Christ]

hey, that's a good idea! i'll definitely angle the cab.

maybe i'll use packing blankets...or do these "horse blankets" have better acoustic properties? has ethan winer studied this?

[jamsmith]

Horse blankets, padding blankets, whatever. I think someone even sell a "recording" blanket you hang on frame to make vocal booths. The key is leaving some air space behind them.

[norman_nomad]

Have you listened to the guitar cab in there without treatment yet?

One mistake a lot of people make is to make a space overly dead.... things start sounding anemic and become hard to mix... sometimes it's hard to pull energy from a really dead room.

I think you should spend a lot of time with cab and mic placement along with a combo of absorbing and reflective materials until you get a combo that sounds right.

You can justify spending a lot of time tweaking it knowing that the cab is just going to sit there in the sweet spot. thumbsup

[gullfo]

i would add that instead of angling it, put the amplifier in the control room and the cabinet in the closet facing up laying on thick carpet padding. i would build any absorbers to be hung on hooks so you can adjust their placement in the closet to create a variety of "room" sounds.

[Kiwiburger]

I agree with the comment that in a box like that, dead is best. It's impossible for the reflections to sound good in such a small space, so much better to kill them as best you can.

What I would do? Forget a cab. Buy a single 12" (or 10" or even 8") driver, and build your own minimal size box out of thickest plywood and 4x4s. Make it a totally sealed box, that will sit on the floor with the speaker facing upwards. Use the longest dimension of the space to project into - in this case upwards.

I dislike fibreglass - not in my lungs and fingers. Foam is misunderstood. You can buy different densities, get it flame and mould ******ent.

I would sit this mini-speaker on a slab of foam, and install a vertical tube of foam - the thicker the better - at least 2" but preferably 4". This tube (imagine a rolled up mattress) would sit around the facing-up speaker. Absorbants actually work better if there is an air gap, so this tube will give best bass trapping than if the foam was glued to the walls. Hang the mic(s) over the top, and cap the tube with another slab of foam.

This is not so different from an old Joe Meek technique of sitting amps on the floor, facing up, and covering the whole mess with a tarpaulin.

The dry tone can be treated with artifical reverb - convolution of real spaces can be very nice.

Ideally - I wouldn't be using such a small space, but if that's what I had, that's what I would do.

[norman_nomad]

Originally Posted by Kiwiburger

I agree with the comment that in a box like that, dead is best. It's impossible for the reflections to sound good in such a small space, so much better to kill them as best you can.

I dunno. I always think it's worth experimenting with the space before assuming it's going to sound bad.

I've recorded guitars in untreated closets with good results.


In fact... one of the clips from my website has guitars that I recorded in a bedroom closet. No treatment... except maybe some clothes on a hanger...

The speaker is facing a wooden sliding closet door and is within inces of it!...so it's getting some major immediate reflections... but this became part of the sound... it actually made the guitar sound more exciting....

I attached the clip.

[jamsmith]

Originally Posted by Kiwiburger

I dislike fibreglass - not in my lungs and fingers. Foam is misunderstood. You can buy different densities, get it flame and mould ******ent.

We aren't talking bat insulution, fiberboard. And you cover it with fabric. You are around it day in and day out without even knowing it. It is used in offices ubiquitously.

While 4 inch foam will start to compete with fiberglass in mid-range/mid bass, it tapers off in low frequencies. Of course you have traps for bass that is difficult in small spaces. I used 1" Corning in my vocal booth and it worked great

[Sigma]

Originally Posted by gullfo

i would add that instead of angling it, put the amplifier in the control room and the cabinet in the closet facing up laying on thick carpet padding. i would build any absorbers to be hung on hooks so you can adjust their placement in the closet to create a variety of "room" sounds.

only reason i said angle is

1. more distance

2. no parallel surface wher it fires..it would fire ito the coner where wall meets ceiling