For some time I've been experimenting with different techniques that would hopefully give good sound in a fairly small room. That's an area where I would like to offer something competitive, but so far all of my systems have been more suitable for medium or large rooms (though some people are using the Jazz Modules in fairly small rooms).
Here are the problems inherent in trying to design a speaker to work well in a small room:
1. Limited real estate available, especially side-to-side. But not only does a speaker physically take up floor space, it also effectively occupies the space behind it.
The solution is to use a narrow speaker, preferably one that can be placed close to the wall.
2. Early onset of reflections. Because the path lengths to the walls are shorter, reflections begin to arrive sooner than they would in a larger room. Early-arrival reflections are more likely to be detrimental from an imaging and coloration standpoint than are later-arriving reflections.
The solution (from a loudspeaker design standpoint) is to have good radiation pattern control as far down into the midrange region as is practical, and aiming this radiation pattern so as to maximize as much as possible the time delay before the onset of reflections. Note that these characteristics and the narrow speaker requirement are mutually exclusive, so some compromise is inevitable.
3. Uneven bass response. The room-interaction peak-and-dip pattern is usually worse in a small room than in a large room, and contributes to many people not wanting a speaker with significant bass extension in a small room.
The solution is to spread around the bass sources as much as is practical, preferably in all three dimensions. In my opinion the ideal would be a Geddes-style or Swarm-style distributed multisub system, but if floorspace is at a premium that's out of the question.
4. Excess room gain at low frequencies. The proximity of the room boundaries results in more boundary reinforcement than speakers normally get, especially if they have to be placed close to the wall. So a speaker designed to be approximately flat in the bass region in a medium or large room will have excess bass in a small one, and if that excess bass is also uneven it can be quite unpleasant.
This is really a free lunch in disguise, as the solution is to have a gentle bass rolloff that starts fairly high up. Because we don't need to generate as much bass energy, we can make the speaker a bit more efficient for a given size. However if the bass is going to be lumpy anyway, we want to err on the side of having too little bass instead of having too much.
The amount of room gain varies significantly from one room to another, and also with changes in speaker (or listener) location within the room. So some adjustability of the speaker's bass response is desirable.
5. Poor driver integration at close listening distances. This isn't an issue in most cases, but at very close listening distances it can be. The ear is poor at resolving the height of a sound source up to about 1 kHz, and then it improves significantly. So if there's a large vertical spacing combined with a fairly high crossover frequency, it could cause problems.
Several months ago I was in the home of a Jazz Module owner and he was listening from close enough to the speakers that if he sat forward in his chair he could reach out and touch them both. I would have expected to hear vertical discontinuity at such a close distance, but he didn't hear it and neither did I. So as long as I don't get the drivers farther apart and/or raise the crossover frequency significantly relative to the Jazz Modules, we should be okay.
