20 to 40 hz responses

[jpv]

I notice in this thread http://www.hometheatershack.com/foru...unt-ahead.html that in most of his plots the low freq. curves remain the same. I have noticed this in my measurements also. As long as I stay within a certain area the response curve remains the same, higher frequencies will show variation. My question is why are these frequencies not affected by placement on my subs or seating position?

[brucek]

My question is why are these frequencies not affected by placement on my subs or seating position?

It's certainly not normally the case. Moving a sub or the listening position can affect any frequency.......

[DrWho]

Lower frequencies have longer wavelengths, which will naturally disperse the peaks and nulls of the modal response over wider regions in the room.

[jpv]

Then the hump I have in my room at those freqencies can only be tamed by an EQ. Bass traps are not effective that low. Is this a result of the room or the speakers, I have two M&K subs. These frequencies fall below my room modes, The size of my room is 18.5 x 13.5 x 10.
Could I not be measuring it correctly?

[brucek]

I suspect it's the room. You could take a near-field measure of your subs. Try and remove as much influence from the room as possible when taking the measure. Perhaps drag one sub to the center of the room away from boundaries, or better yet, take it outside....

brucek