Others experience re: subs and Magmepan 20

Jim, Rythmik Audio has two sealed subs featuring dual 8" woofers, the F8 and FM8. The only difference between them is the FM was designed to be used as a mid-bass woofer, it’s x/o to a lower-frequency sub being 4th order at 50Hz. Both operate up to 250Hz, and both incorporate the Rythmik Direct Servo-Feedback amplifier.

Also, co-designed by Rythmiks Brian Ding and Danny Richie of GR Research is the unique OB/Dipole Sub, available with dual 8" woofers, though dual 12’s is the more common choice. This OB/Dipole Sub is the ultimate sub for use with all planar speakers, for obvious reasons.

By the way, both Brian and Danny are adamant that because of the design of the 8" and 12" woofers (designed in house specifically for open baffle implementation, and custom manufactured by TC Sounds for Rythmik and GR exclusively), and how they are controlled by the Rythmik Servo-Feedback circuit, the 12" is just as "fast" as the 8", but capable of considerably more output. The sense of "speed" in a woofer is in how quickly it returns to "rest" after the signal has stopped, not how quickly it starts (Rythmik/GR subs have been described as "stopping on a dime"). Subwoofer frequencies are relatively "slow", but woofers, once set in motion, tend to stay in motion. That’s where the Rythmik Servo-Feedback circuit comes into play. If you’ve ever heard the Infinity IRS loudspeakers, you know what I’m talking about. I formerly owned the mini-IRS, the RS-1b (featuring six 8" servo-feedback controlled woofers per side), and the pair of Rythmik Audio/Gr Research subs I now own are considerably better. Leaner, cleaner, no boom, no bloat. It’s the only Open Baffle/Dipole Servo-Feedback Sub in the world! Seriously, if you don’t have room for a pair of Magneplanar Tympani T-IV bass panels (great as subs for Maggie MG series speakers), this is the sub to own.

imdoc---akg_ca’s repost included a few assertions (well, a lot more than a few, and I didn’t make it through the whole thing :-) that must be disputed.

1- "it is virtually impossible to build a really good subwoofer for under $1000. Yet most of the subwoofers out there sell for between $500 and $900."

First, it is NOT impossible to build a really good subwoofer for under $1000. There are a fair number of Maggie owners very satisfied with their Rythmik F12G subs, to name just one under $1000 sub. I have heard the Vandersteen subs, very fine products, on many occasions, and while not wishing to pit Vandersteen against Rythmik, I can safely say that anyone who is satisfied with the Vandersteen is very unlikely to not also be so with the Rythmik. In fact, one’s preference might flip after having heard both.

But come on akg, do you really think the owner of Magnepan MG20r’s is limited to a sub-$1000 (no pun intended) subwoofer?! There are a number of incredible subs available which are valid competition to the Vandersteens, if funds are available.

2- "This is the only subwoofer (referring to Vandersteen of course) that is specifically designed to be inserted into the highest of high-end music systems without doing any harm to the precious signal."

What a ridiculous, arrogant statement! That is patently false. Whoever wrote that sentence must be woefully ignorant of the products of a number of designer/manufacturers who set their sites on that exact goal. Richard Vandersteen is not the only talented speaker designer out there, for gawds sake! I could name a few, but I’ll just mention Danny Richie and Brian Ding, of GR Research and Rythmik Audio respectively. Brian Ding designed his line of subs (which incorporate Mr. Dings patented Direct Servo-Feedback technology) for music reproduction, and Danny Richie and he collaborated on a 12" driver offered with either an aluminum cone (for high volume application, including loud music and/or home theater) or a paper one (the "G" in the model designation of the Rythmik F12G, which uses the paper-cone version of the woofer, refers to GR Research) specifically for music listened to at less than extreme volume, it’s lower mass providing higher low-level resolution.

In addition, they also collaborated on a very unique subwoofer designed specifically for "the highest of high-end music systems"---an open baffle/dipole sub (two 12" woofers mounted in an OB "H-Frame", powered by the Rythmik Servo-Feedback amplifier), the ultimate design for mating with a dipole speaker such as Maggies (and ESL’s, and Ribbons). The GR Research/Rythmik Audio OB/Dipole Sub is, and I say this with the upmost respect, a completely different animal than the Vandersteen, and all other, sub(s). Is the writer of the quoted sentence even aware of GR Research and Rythmik Audio products, or all the other high-end designs now available?

3- "In fact his (Vandersteen) crossover is so ingeniously simple that it is a wonder nobody else thought of doing it the same way."

It IS simple, and it WOULD be a wonder if nobody else thought of doing it the same way. But they DID, and a long, long time ago! Advanced enthusiasts having been employing a simple 1st order crossover as a high-pass filter since the 1950’s. You don’t really believe no one before Richard Vandersteen thought of something so obvious, do you?! The Dahlquist x/o in the 1970’s used that exact technique---a single capacitor to filter the signal going to the main speakers.

Now, if you’re talking about Richards technique of taking the signal for the sub from the speaker taps of the main power amp, Richard is not the only one doing that either. Both Rythmik Audio and REL offer the same hookup, Rythmik also providing line-level connections.

All of this is not to say that the Vandersteen subs are not very fine products. Far from it---they are great. But they are not the only really good ones available for use in "the highest of high-end music systems". They do have some competition, and may in fact have some which surpass them. There are even Magneplanar fanatics who use the Tympani T-IV bass panels as subs for their MG series Maggies!