Sealed subwoofer for ESL-63

Jzzmusician wrote: "I’ve got a pair of Quad 2805’s. I love pretty much everything about them but I would like a bit more bottom end... What would you recommend for a subwoofer(s) in the 2-3k range?"

I’ve owned three pairs of Quads and many pairs of SoundLabs, so I’m somewhat familiar with the superb pitch definition of a good dipole bass system. You can hear every little nuance of what the bass player is doing.

In my opinion, the most promising approaches to adding deeper extension to your Quads are probably four small monopole subs, and two dipole subs. Both approaches have similar smoothness across most of the bass region. Briefly, the more bass sources the better, and each dipole is like two bass sources, from an in-room smoothness standpoint. In both approaches, the bass energy from all these different sources bouncing around the room combines in semi-random phase to produce much smoother response than you’d get from a single sub.

Obviously two dipole subwoofers are gong to blend well with two dipole main speakers. But four small monopole subs, scattered around, have about the same in-room smoothness as two dipoles, so they also blend well with two dipole main speakers.

But there is an important difference:

At the bottom end of the bass region, where the wavelengths typically become quite long in relation to the room’s dimensions, a multiple monopole system would tend to have a rising response, because at these long wavelengths their outputs are effectively combining in-phase. And in-phase combining results in 3 dB more SPL than semi-random-phase combining.

On the other hand, at these long wavelengths, the in-phase and out-of-phase energies of the dipoles will combine to produce a falling response, because they are summing towards complete cancellation.

Neither is ideal. But the little multi-sub system has a trick up its sleeve: You can reverse the polarity of one of the subs! This actually results in smoother response over most of the bass region, and then no fat-sounding hump down at the bottom end of the bass region. Smooth bass is "fast" bass, and the net result is smooth bass that extends lower than a comparable dipole subwoofer system would go. And subjectively, the distributed multisub system has the impact that dipole systems lack. So arguably best-of-both worlds: Articulation and pitch-definition competitive with a good dipole, but with impact too.

Yeah I got a dog in this fight... four small dogs, to be precise. So feel free to take my comments with as many grains of salt as needed.

Duke

dealer/manufacturer/distributed multi-sub guy