The low frequency response of the system should be addressed first.  In the design stage our first steps include placement of the seats and subwoofers.  The goal of this is to find or manufacture an area of similar deep bass response where we can equalize any remaining anomalies to provide a consistent sense of bass for all listeners.  It also means matching the overall response of all speakers.

We’ve heard the term boomy bass.  Intuitively, it could mean that the bass is too loud, but that would shortchange those among us who love lots of bass.  A more damaging condition is when one or more bass frequencies are much louder than the others.  It is a direct result of room mode distortion of frequency response.  This is what we mean by boomy bass.  The result is a ringing effect where the low frequencies of a sonic image are detached from the higher frequencies of the image.  In many cases, the bass becomes somewhat monotoned, and there is a sense of boom, as if someone is pounding on a wall.

In the HAA workshop we use a recording of a stand-up bass (double bass) to review low frequency response.   As the musician plays the song the range of bass frequencies show some notes are much louder meanwhile others are too quiet, a distorted portrayal.  In some rooms, the ringing, boomy frequency seems to unnaturally surround the listeners, at other times the subwoofer appears to be the location of the bass and is localized.  Both are wrong.  The low frequencies should appear to be emanating from the sonic image of the stand-up bass in the soundstage.  The entire range of frequencies of the instrument should be integrated as heard from the same place.