Listening room measurements / How'd you do it?

[pearsall001]

I presently have a GIK monster bass trap & two Echo busters corner traps. The difference they made was quite noticable. I want to take it further w/ more absorption panels, bass traps, diffusion panels, etc. but first I'd like to measure my room's acoustics. With room measurements I can then decide on a plan of action. Did any of you guys do this & if you did how did you do it? I'm not very savy with this sort of thing. Hopefully the simpler the better.

[dorokusai]

I hired a hobo to hold a microphone/SPLM in different parts of the room so I could plot my graphs. Then we did shots of Old Grand-Dad until I passed out....I have not gotten that microphone back yet.

[amulford]

Check your colon...

[Ruin]

Ouch

[organ]

LOL:D

ok, now to your question. imo, probably best to do it by ear. Do a little at a time.

[pearsall001]

WOW!!! I didn't realize I was on the Comedy Central forum. So much for asking a question here. I thought you guys were audio heads that knew all the answers, or at least thought you did. Oh well, my bad.

[dorokusai]

Do you have an EQ to adjust the levels that you're wondering about in the first place?

[amulford]

I don't measure my rooms. If you do, there is software that will help you, but that's about all I know...

[unc2701]

High frequency- do it with your ears... there's no perfect method here & some people like a bright room vs a "dead" room. You cannot have too much diffusion, you can have too much absorption.

Low frequency: Get a radio shack SPL meter. First test: run a single test tone at a time & go from your -3db response on your speakers to about 250 hz. make the tones fairly long. Start in your listening spot, then get up and move around the room and see if your db's change a lot. This will usually happen at your room modes- if your room is a rectangle, you'll have 3. One each for height, width, depth. Take each dimension and divide 1130 by it.

Example: If you've got a 16 foot wide room, you've got a mode at 70.625 hz (16*70.625=1130). Run a 70.625 hz test tone and wander the room with the spl meter. if the readings are wildly different at various locations (equidistant from the speakers), you need more bass absorption. Using the standard absorption methods, you'd need a bass trap at least a quarter wave length from the reflecting wall or 4 feet (hell no!!!). However, tympanic absorbers can do the same in about 4", depending on the dampening and resonant feq of the panel.

Helmholtz absorbers can also be tuned at your room's modes, but they're not very effective at low freq since the port area is the only place where you get any absorption. PM me if you need the formulas to build one.

If you still have bass issues, check out the SpringTrap, it's a combo vibrating panel/ helmholtz resonator- a freind uses them w/ studio work and I've had some very cool email exchanges with the designer. I don't have any in my house, but that's deffinitely a future purchase.

[tryrrthg]

Room EQ Wizard (http://www.hometheatershack.com/roomeq/)