I have a few problem frequencies in my theater that need addressing.

I have a post over at HomeTheaterShack, so I won't cross post the pics here, but check them out for more detail: http://www.hometheatershack.com/forums/h....html#post94903

The summary:
A 2/3 Octave null at 33 Hz, which corresponds with the long axis of the room (~19 feet half wave)

A narrow bandwidth null around 100 Hz, and a 1/3 octave null around 260 Hz.

those are the nulls. I also have a peak at 130 Hz that is around 6dB up from where it should be on the crossover slope.

Due to SAF, I only have the back wall, behind the dvd rack, and front corner to play with.

Any advice is appreciated.

Thanks,
Anthony

Oops, I think I figured out my 130 Hz / 260 Hz problem. The opening of my dipole sub corresponds exactly with the half and quarter wave of those frequencies (half being the null at 260 and quarter being the peak at 130). I'm going to test these separately.

That still leaves me with the 30 hz and 100 Hz nulls to contend with. Any ideas there?

The obvious advice is you need bass traps. The more pressing question is where you can put them without pushing the limits of SAF. My motto with acoustic treatment is, "You can have effective, attractive, or affordable - pick any two." In your case getting enough bass trapping to make a real improvement will cost more than just the traps. One solution is to get a fabric stretch-wall system to cover larger areas of wall that have bass traps and reflection panels. There's no magic bullet here.

--Ethan

Thanks Ethan.

Followup question: take SAF out completely.

Are you thinking true absorptive traps, panel resonante traps, or helmholtz style?

I have a lot of volume in my riser that I could put some ports on for a helmholtz resonator (it is sealed completely to the back/side walls, and floor.

I was also thinking about a "chunk" style trap behind my DVD's (corner triangle rack). it would only be about 8" deep, but would run mostly floor to ceiling.

My wife doesn't care about aesthetics, more room usability. So a big black monolith in the corner of theroom doesn't both her. Walking around an obstacle every day or bumping her elbow on something when she sits down, that's the kind of stuff she'll veto.

Thanks for the help.

For a room that size I'd stick with plain ol' porous absorption, either panel or chunk style.