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Suck out at 165 hz...can't find the cause

I have been focusing on improving my room and dealing with its effects on sound quality. I have been able to deal with some peaks in the 40-100 Hz region, and my room/speakers now measure generally quite well.

But I have a fairly narrow band suck out centered at 165 Hz, that is fairly deep (around 10 db). I have tried moving the speakers, putting up soft stuff (blankets, pillows, human beings) along the axes of the room, etc. Nothing seems to affect it at all.

Could this be something related to the speakers themselves (e.g. internal speaker cross-overs)?

This is an analog two-channel system with a Jeff Rowland Capri pre-amp, Kharma MP150 ampifiers and Wilson Benesch Curve speakers. Unfortunately, the reviews of these speakers do not have any measurements with them, so I don't have an external reference.

The amps are wonderful but are not super powerful, so I'm thinking that an RCS system won't help because trying to get rid of a dip of that degree will force the amps to work too hard and they probably won't be able to do it anyway.

Your thoughts as to what might be causing this and any advice on dealing with it are most appreciated.

Thanks!

--dan
dgaylin

Showing 2 responses by shadorne

shadorne's avatar
shadorne
7,491 posts
 
If it is fairly consistent across the room then it could be woofer to floor and ceiling height effect (quarter wave cancellation) - a down firing subwoofer crossed over at 90 Hz might help.

FWIW a null/suckout at 165 Hz is not too bad provided it is narrow.
shadorne's avatar
shadorne
7,491 posts
 
Depending on the order of the mode and type (Axial, Tangential or oblique) you will get peaks and troughs at different places across the room. The worst effects are when these combine at th elistening position.

Some things go across the entire room. The quarter wave cancellation reflection of the bass frequencies from the wall behind the speakers generally affects the entire room.
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