Paul McGowan gets asked about rotary subs.

bdp, I tend to agree, even though I've never owned ET  speakers.  I have owned a few pairs of Maggies and I agree the ET design makes more sense to me.  Better design to avoid a crossover through so much of the range and also more durable.

Regarding Paul's comments, he seems like a nice guy and obviously an enthusiast (as a manufacturer), but I've seen several bits of over-simplification or plain misinformation in his comments.

To your main point, I never understood why ET doesn't have more market presence either?

.....all electrostatics are planars

I'm not sure I would call the Martin-Logan curved electrostatic panels a planar loudspeaker. I would call it a panel loudspeaker, though. A plane is flat...

@pryso: Excellent point about the LFT’s avoidance of a crossover through much of the audible range. For those who missed it, the midrange planar-magnetic driver in the LFT-8 reproduces from 180Hz up to 10kHz, with NO crossover! That is a very big deal. Fans of single-driver designs take note!

Bruce Thigpen was very impressed with Jim Winey’s original Magnepan design (the Tympani), but thought he could do better. So he designed his LFT driver as a push-pull transducer, in contrast to the single-ended of the Tympani. A push-pull driver produces less distortion than a single-ended one, of course (the wires attached to the Mylar film of the drivers better remain in the field strength of the driver’s magnets). Winey eventually designed and built an excellent push-pull ribbon tweeter, but the midrange drivers of his MG.7, 1.7, and 3.7 remain single-ended. Also, the LFT driver is built into a substantial metal frame, as opposed to the Mylar of the Maggies being merely glued and stapled onto the speaker’s MDF frame.

The crossovers for all the LFT-8b drivers (the p-m midrange and tweeter, and the 8" dynamic woofer in a sealed enclosure) are simple 1st order/6dB-octave filters, with few parts. And the LFT-8, while very low in sensitivity, is an 8 ohm load. The m-t panel itself is an 11 ohm load, so great for tube amps. The LFT-8 comes with two sets of binding posts, for easy bi-wiring or (even better) bi-amping.

The ET TRW-17 Rotary Woofer has been described (by Peter Moncrieff in International Audio Review, I believe) as the world’s only true subwoofer. That is because it is designed and intended to reproduce "only" 20Hz and below. Most loudspeakers have a hard time reproducing even 40Hz at lifelike SPL with low distortion, and even the best subwoofers can’t do 20Hz very well (except perhaps the Rythmik’s).

The current Stereophile contains a review of the Klipsch La Scala AL5, and both the reviewer (Alex Harbestad, a name new to me) and John Atkinson’s measurements revealed the output of the AL5 to plunge rapidly at 50Hz. And that from a 15" woofer! Totally unacceptable, to me at least. The lowest note produced by a standard 4-string bass (electric and acoustic)---the E string played "open"---is located at approximately 41Hz. If a loudspeaker can’t reproduce 41Hz, I ain’t interested ;-) .

We all know that hi-fi’s are still---after 100 years or so of development---quite incapable of reproducing music that comes close to that which we experience when heard live. I have long believed a large part of that failing has to do with hi-fi’s failing to reproduce (and perhaps recordings failing to capture) the physical properties of live music. Live music is sensed not only by our ears, but by the rest of our bodies as well. While our hearing may not perceive frequencies below 20Hz or so, our bodies certainly do.

I would love to hear the TRW-17, and have seen pics of it in the system of one audiophile (he installed it in the floor of his listening room). He pairs it with his loudspeakers, which are a pair of Martin-Logan ESL’s augmented with the bass panels of the Magneplanar Tympani loudspeakers. Yeah, baby! I LOVE the sound of the Tympani bass panels (I own a pair of them as well, the T-IVa), but they are good down to only 30Hz at best (when braced and fed a LOT of power).

I have 2 sets of lft 8b they are great for me .Bruce answered all my questions.was super professional and knowledgeable.  Speakers arrived as advertised. I have them bi amped.thx

Interesting subject. Can think of a few things that might have slowed ET down.

1. In their beginning years Magnepan partnered with Audio Research a lot. Not a bad company to be associated with.

2. ET went hybrid with planar/cone woofer. People might prefer running Maggie’s with sub.

3. IMHO ET acquired a very tweeky reputation. The air tonearm was rough to keep working. Friend was always fiddling with it. Noisey Air pump had to be located in another room. I remember a home-made air filter, built into a milk jug, to reduce air turbulence. The system also had to be routinely purged of condensation and cleaned. The only arm I remember being as big of a pain was the Souther linear tracker. The rotary woofer is also way out. Bruce is very smart, but might need to pay more attention to convenience.

Often see the argument about ET speakers having less distortion than Magnepan. ET has magnets in front of the driver, causing diffraction. So which distortion is worse? Does the ET woofer have less distortion than a Magneplanar bass panel? Might depend on frequency range and volume. Would like to hear the ET speakers.

Thanks,

aldnorab