dealing with room modes.

First of all I'd like to thank all of those who contribute to this form. It's helped me a lot over the last year. Last summer I built a studio in my detatched garage. I am now at the point where I am working steadily out of it, but my room is not sounding as good as I would like. the problem I am having is that in the area right in front of the console and monitors, I have a build up of about 125 htz. when I stand up in the spot where my chair is, it gets better, but when stand on the chair with my head close to the ceiling, it builds up again. and it seems to sound the best when I am standing a few feet behind where my chair is. So the build up is about 5 feet from the front wall right where I am always sitting, and its becoming very annoying. The main room that I track and mix in, is about 20 by 14 by 8. here are some pics. pic 1 2 mid high bass traps (160 to 220 htz) 4 by 8 feet each pic 2 I've got 2 3by8 deep bass traps using the ethan winer design (thanks ethan) pic 3 The back wall is covered with 2 convex pieces of peg board, that are filled with oc 703 and rockwool pic 4 The ceilings have 4 angled sheets of 1/4 inch board with the tops covered with 703, and rock wool. the centre of the ceiling of covered with the fiberglass ceiling panels pic 5 the front wall has a 4 by 8 piece of 2 inch linacoustic duct liner which has a SAC of1 down to 500 htz, and .66 down to 250 htz

so I have a few Ideas, but I would love to hear yours. 1) redo the front wall behind my monitors with deep bass, and high mid bass absorbing panels, like ethan winers design, 2) try to hang 2 bass traps directly above my head hanging from the ceiling. this will be more difficult as I already have the 4 large panels up, and I am running out of trusses to anchor too. my lights are up there as well. thanks in advance.

cchord59 wrote:

so I have a few Ideas, but I would love to hear yours.

Repeat after me: More bass traps. More bass traps. More bass traps. :) Seriously, this is your only viable option. But trap placement matters too, especially if you have a build up at a specific place and frequency. One great way to find the best place for more traps is to play bass-heavy pink noise through your speakers, then walk around and climb up on a ladder etc listening for where the bass is loudest. That's where more traps should go. (Or use an SPL meter or a microphone connected to a recorder and VU meter.) It so happens I have exactly the noise source you need here: http://www.realtraps.com/lf-noise.htm Also experiment with speaker placement and listening at different spots in the room. These are free to try, and can often make a big difference. --Ethan

cchord59 wrote:

So the build up is about 5 feet from the front wall right where I am always sitting, and its becoming very annoying.

Sounds like you're sitting at a boundary interference peak from the front wall. (Which could be exacerbated by the presence of several modes at this frequency.) Moving your speakers and listening position back from the front wall might help, but could also move the problem to another (equally annoying) frequency. Regardless, it's probably the best thing to try initially since it doesn't cost you anything. If that doesn't make it better, you might try beefing up the front wall absorption - either pull the 2" material away from the wall 2", or - better - make the front wall treatment about 6"+ deep instead. (I.e., add two more 2" layers over the top of what you have.) You might also try this over a wider area than what's shown in the "front wall" pic, making sure the treatment area overlaps the rear of each loudspeaker by a foot or two in each direction. Make sense? :)

thanks alot it all makes sense I built one trap today that went together well, but I am wondering if anyone can tell me the frequencys that is will absorb down to. Its built on a frame of 1 by 4s with 2 inches of dense rockwool and a 2 inch gap between the wool, and the wall. I am hanging them like pictues. its 4feet by 4 feet thanks.

here are some pics of the traps I made. Nothing special or new, but I thought someone may be interested to see them. I just layered to 1 inch panels of rockwool together to make 2 inch with a 2 in cavity between the rockwool and the wall. I wonder if these panels made with 703 would absorb differently than with rock wool?