Asymmetrical Room Treatment

Chrisar wrote:
"While I know that having a decent amount of airspace between a trap and wall is beneficial, is there an upper limit on this? My guess would be that about 1 or 2 times the thickness of the trap would be ideal, but I am just guessing here"

If you're using fiberglass filled absorbers (which you are) then you simple change the frequency at which the absorber maximizes its effectiveness at by changing the air space distance. I don't believe there is anything intrincically good or bad about how far you pull the trap out, it's a matter of using that flexibility to your advance to attenuate a problem frequency. Remember that the absorber works best when the particle air speed is fastest which is at the 25% mark of a frequency's wavelength. It's easy enough to calculate what that is as follows using a 440Hz frequency for example:

Speed of sound 1130 / 440Hz *12inches = 30.8" then multiply that by 25% and you get 7.7" which is the airspace needed to max the absorber placement.

I would think other practical issues like asthetics or not having the absorber blocking a walking path through the room etc might factor into it too.

I think Kevin has some very good answers, though I am not sure if the OP can take advantage of all of them due to his restrictions in renting.

My question is regarding a 4" diameter (I am assuming it round) or is it a panel type? If its round, doesn't the 4" diameter preclude it from acting as a bass trap? I was under the impression that for the round tubes, one need really about 16" to get into the bass notes?

FYI - I spent my evening installing some new Real Traps - Corners panels (mondos), a couple of PFZ (?) on the ceiling (suspctd about 4"). On one wall, left, I have four 2 X 2 X 4" thick Real Trap Panel sound panels (tilted, out 6" at the top and flush at the bottom) in a 2 X 2 pattern with 2" between each panel. On the opposite side where my window is, I glued laminate thickness playwood onto the auralux backing. They are 4 feet tall, 2 feet wide and 2" thick. The window is about 3 feet tall by about 5 feet wide. I basically bent the laminate so that panels are wedged between the top and bottom window framing - bowing outwards.

My back wall (behind me) is about 15 feet behind where I sit and am justing letting the physical aspects of what behind me defuse the sound (I have nothing specifically addressing the soundwaves behind me due to the distances involved and it doesn't sound like I need anything).

Finally, I have two of the auralex panels between the speakers (in front of the fireplace opening, positioned at about a 15 degree angle - with a point in the center).

I need to put some decent heavier drapes up over the window and auralex bowed panels, but already the room is sounding much better.

Bass is much tighter and I can play a much high SPLs without the sound breaking up, conjecting and just becoming over energized.

Anybody want to make any additional comments it would be fine. I think I need still some corner (wall/wall/ceiling triangles and possible raise higher my front wall corner traps which are pretty wide frequency ranging).

Ckoffend.

I'm sure he's talking about a 4" panel.

Also, it sounds like you're putting together a really nice room.
I would stress that the 15 ft. space behind you should also be treated in some mannor.
Stand at your listening position and clap your hands, do you here any echoe ? If not you are good to go.
If so, you need to dampen the area behind you.

15 ft. is a long distance and the reflections at 15 ft really turnes into 30 ft. by the time it arrives at your chair. That's a huge timing gap.

Anouther point I'd like to make is that if you treat a room one wall at a time and you sit to listen to the results, if you make a mistake and over dampen the room, you will immediatly know that you went to far. Your sound stage will collaps.

It sounds like the combo of absorbtion and deflection, your going to have a great sounding room.

There's nothing in the electronics world that can give the upgrade that a well treated room can.
If someone is reading this and never heard a treated room, then you need to treat your room.
It is the most bang for your buck in audio.
Have fun.
John

Ckoffend - Are you asking if the original poster (Chrisar) is using 4" thick absorbing panels? I think he said he is. Whether it's a 4" thick panel or 4" diameter circular trap or a 4" radius semi-circular trap, 4" is still only 4" and is the bare minimum considered for a broadband absorber. The thicker the better because you don't want the trap to act like a low-pass filter which would only absorb mid/high frequencies as it'd skew the tonal balance of the reflections and the reflections of those reflections from the speakers you paid dearly for. So, go thick or go home . . . so to speak. My front wall corner hemi-cylindrical diffusers/bass traps have a total thickness of 37" which includes an 8" air space, as my 21' * 14' room can acommodate it.

Are you using the room for 2channel music or HT as the back wall treatment varies? Check out Dr Floyd Toole's book - it'll teach you many useful and pragmatic things to help you decide what your room needs and what kinds of treatments go where.