I'm speaking here from an imprecise understanding, (FWIW), but my
sense of 'bass slam' is as dependent on the harmonics as on the
fundamental -- they both have to be present, appropriate in amplitude,
and undistorted. You may have issues with the harmonics which could be
high enough in frequency to be muddled by first reflections. Have you
tried putting centering your speakers on the long wall well away from
the end walls. Your room is big enough to not feel cramped with this
arrangement.

By the way, many moons ago you recommended Obligato caps, and led me
to try them in the parafeed positon in my S.E.X. Amp. I like the
result very much. I meant to mention this to you in Dallas, but
the opportunity didn't arise. Thanks,

Skip

This is one of the long standing myths about audio. If this statement were true, headphones wouldn't work, and there would be no bass in a car. When the wave length becomes large with respect to the space, the entire space pressurizes and the air vibrates as a single mass. Your ears can't tell the difference from a passing wave train and a pulsating pressurized room.

The rest of the discussion of room problems was correct. In these small rooms most of the nodes are along the walls and in particular in the corners. The loops are in the middle of the room. I was fortunate to find the bass performing reasonably at the seat I planted my visitors in.

Bob

Bob

I suspect this one is actually from the walls. They're as rigid as the floor in a concrete basement, so the destructive interference from a standing wave will be just as strong.