Room gain and its affect on audio quality

[mojave]

Lately I've been wondering what effect room gain has on the audio quality of the bass. For a sub, whether sealed or vented, you get the lowest extension when the sub couples with the room and provides room gain. Because a sealed sub has a 12dB/octave rolloff, its rolloff can mirror the room gain to provide an even response with quite low extension.

Recently, NekoAudio wrote the following:

Personally, I try to minimize room gain when using a subwoofer. Because that's due to constructive interference, which means delayed energy. And thus smearing.

A subwoofer driver at the floor means it is placed at one end of a wavelength that can be reinforced by the next driver movement. Same as in the corner or against the wall. Moving the driver away from that location prevents the driver from adding to a standing wave.

Do some like the sound quality of bass better with full range speakers because there isn't as much room gain? Open baffle subwoofers are also said to sound great. Is this because they are pulled out from room boundaries?

[dvenardos]

I saw that too and have always found ported subs to sound best when positioned away for the corners.

The open baffle subs have a dipole radiation and are therefore directional so you shouldn't get the room interaction that you do with monopole subwoofers.

http://paws.kettering.edu/~drussell/Demos/rad2/mdq.html

A dipole source consists of two monopole sources of equal strength but opposite phase and separated by a small distance compared with the wavelength of sound. While one source expands the other source contracts. The result is that the fluid (air) near the two sources sloshes back and forth to produce the sound. A sphere which oscillates back and forth acts like a dipole source, as does an unboxed loudspeaker (while the front is pushing outwards the back is sucking in). A dipole source does not radiate sound in all directions equally. The directivity pattern shown at right looks like a figure-8; there are two regions where sound is radiated very well, and two regions where sound cancels.

[tesseract]

This makes me wonder how the CS18.2, or any opposed driver sub, would perform with one driver wired out of phase. Any data on isobaric sub room interactions?

What works in one room will not necessarily work for everybody, though. Here is something to consider.

http://www.diyaudio.com/forums/subwoofers/159935-dipole-sub-small-room.html