Which subwoofer should I get?

Brian Ding---designer/owner of Rythmik Audio---recommends low level hookups over high level, but offers a couple of plate amps which include high level binding posts for those who want it.

I know the argument regarding feeding your main speakers and subs the same signal (from your power amp), but I consider that argument flawed. If the power amp were "perfect" (a straight wire with gain), there would be no difference between the output of your pre amp and your power amp (except in gain, watts, voltage, current, etc.). Assuming for the sake of argument that no power amp is perfect, the high level argument is therefore to add the same distortion (from the power amp) to the sub as your main speakers receive.

Let’s use a tube amp as our case study. Tube amps have long been considered slightly inferior to solid state when it comes to the reproduction of low frequencies (the Atma-Sphere OTL amps being one notable exception. A lot of the problems in tube amps when it comes to bass is the sound of output transformers, which OTL’s and most solid state amps are free of).

So with a high level hook up, you are adding the worst aspect of a tube amp to the one frequency band subs are made to reproduce: low frequencies. As the amp (presumably, and hopefully) does not suffer from that ailment in mid and high frequencies, your subs may very well be receiving a signal more different from what the speakers receive than if you were using low level connections.

At any rate, with a plate offering both high and low hookups, you are free to try both, and use the one you prefer. Rythmik Audio offers a few different amps that include both high and low level hookups. And all the Rythmik amps include a very valuable control: a continuously-variable 0-180 degree phase control, for time aligning your sub(s) and speakers. Most subs offer instead a simple 0/180 degree switch, which is of very limited value. A continuously-variable phase control allows you to find the best location in the room for the sub (in terms of bass nodes), and to then use the phase control to electronically "move" the sub (in the time domain. Rythmik labels the control Phase/Delay. Delay only, as it is obviously impossible to move the sub ahead in time.) so as to be in phase with your speakers.

I heard my first ’high end" loudspeakers in 1971. One was the Infinity Servo-Static, the other the ESS Transtatic. Both had woofers that reproduced pretty low bass, the Infinity by virtue of a single servo-feedback 18" woofer, the ESS a KEF B139 woofer in a transmission-line enclosure. The Infinity retailed for $2000/pr (a lot of money in 1971), the ESS $1200/pr. Being an itinerant musician, I could buy neither.

Then in 1982 I saw a pair of the Transtatics for sale locally, for $400. One B139 had been replaced with a knock-off, but a call to ESS and the speaker was restored good as new. I still have 'em. Back in ’73 I had heard the original Magneplanar loudspeaker, the Tympani T-I. It was love at first sight, and I bought a pair. I was stunned by the quality of the bass produced by the two woofer panels of the Tympani, which reproduced the sound of my Gretsch 26" bass drum (recorded in my living room with a pair of small capsule omni condenser mics plugged into a Revox A77) better than any other speaker I had heard.

I provide all the above info to establish my love of clean, lean, "un-fat" reproduction of the low frequency sounds produced by percussive instruments, in particular. Bass drum, piano, and acoustic and electric bass, first and foremost. I have made music with a lot of electric bassists, and with three players of upright acoustics. The sound of an acoustic bass is very unique, it’s character being like the low register of an all-string orchestra. Like the low register of a piano, but more "sinewy".

Harry Pearson chose the Tympani bass panels as the woofers in his custom Frankenstein loudspeaker creation, feeling they reproduced bass unmatched by normal dynamic woofers. Having lived with Tympani’s on-and-off for over 50 years, I completely understand his opinion. Tympani bass is free of the "plumpness" most woofers add to the sound of an acoustic bass.

When Danny Richie of GR Research approached Brian Ding of Rythmik Audio, it was with the intention of combining Danny’s talents at designing OB loudspeakers (including woofers) with Brian’s excellent servo-feedback woofer system. The resulting product is the GR Research/Rythmik Audio OB/Dipole Servo-Feedback Woofer, the only one of it’s kind in the world.

I say all this because I find the OB Woofer to sound more like Tympani Bass than any other woofer using dynamic drivers than I’ve heard. Brian Ding himself finds the OB Woofer to sound too lean, but I (and Danny Richie, and other OB Woofer owners) disagree. I think all other woofers sound too fat. I base that on my experience playing a drumset right next to an acoustic bass, as well as hearing lots and lots of bass drums and pianos in recording studios. You would be amazed at how much electronic manipulation recording engineers add to the raw signal coming into the monitor booth.

But the OB/Dipole Sub is not for everyone, or every system. For those people and systems, the regular Rythmik Audio subs will do just fine.

Oops, "were" it not.

I would suggest any of the Rythmik Audio models, where it not for the fact that the company does direct-to-consumer sales only. I'm not sure what their audition policy is, so head over to their website to at least check them out. Then go to the RA AVS Forum, to see what RA owners have to say.

REL lovers often cite that company's excellent subs as being unique in offering high-level connections on speaker binding posts. That is not true; Rythmik offers a number of different plate amps, a few featuring high-level connections. The Rythmik plate amps offer one feature the REL's don't: a continuously-variable phase control, imo indispensible. Others include variable damping, and a choice of crossover filter frequencies and slopes. And all Rythmik subs feature stop-on-a-dime transient performance, thanks to the patented Rythmik Direct Servo Feedback control of the woofers.