Subwoofers for Martin Logan CLX's

Dipole planar loudspeakers have long been known to be very difficult to successfully mate with subwoofers. One reason for that is that almost all subs are monoploes,  not dipoles. Wendell Diller of Magnepan has long maintained that monopole subs "Do not work with dipole loudspeakers." Magnepan has been working on a dipole sub for a number of years now.

No need to wait; GR Research and Rythmik Audio have been offering an OB/Dipole woofer system for over ten years, and it has enthusiastically found favour amongst owners of dipole speakers. Two such owners are AudiogoN members jaytor (4 woofers per side, a pair of Duals stacked) and bigwave1 (two woofers, one Dual). You can see the sub in their virtual systems. Take a look at bigwave1’s frequency response graph for proof of bass response flat to below 20Hz! The sub is offered in a 2-woofer version (the Dual) and a 3-woofer version (the Triple).

The GR Research/Rythmik Audio OB/Dipole Servo-Feedback Woofer System sounds very different from sealed and ported subs. It sounds "leaner", like the bass produced by large planar/magnetic dipole loudspeakers. The sound character of the sub is the closest thing I’ve found to the bass produced by the dual bass panels of my Magneplanar Tympani T-IVa loudspeakers.

I really like the way the Rythmik subwoofer(s) integrate with my Maggies.

Please don't laugh (too hard)

It's not exactly state of the art but I use a single Janis W1 sub with Acoustat 3 speakers and it is a great match. It's very fast and blends really well when crossed over at about 50Hz. I would not recommend using it with its original Interphase amplifier because it shrinks the soundstage among other things. I'm sure that the Rythmik is amazing but the Janis with a decent crossover and amp, or even a Dayton subwoofer amp fed at speaker level sounds wonderful. A Marchand Sub amp would be perfect. I first bought one in the early eighties but sold it. The one that I use now cost me $41.00. The slot-loading and short-excursion driver permit the Janis to mate well with electrostatics in a non-EDM oriented system. Well, that concludes the low-budget section of today's discussion.

Thanks so far for the recommendations. Just to clarify my friends not interested in budged level subwoofers. I don’t think he will even consider lower level gear at this point or DYI options. His tastes and budget are in the upper audio gear level. I can’t see him buying an entry level subwoofer when he already has RELs top models from ten years ago. He’s looking for an upgrade to what he already has. He will most likely buy two REL sub at $30,000 if I can’t convince him to change directions. I’d like him to buy some OB servo subs from GR reasurch but he is hard to convince a sub below $2000 will out perform the top REL’s. But I’m trying.