Paul McGowan gets asked about rotary subs.

@wsrrsw , as soon as I followed your link, I *L'd*....

Upon reading our OPs' opening statement and his desire for 41hz, the LFT 8s' seem like the rational choice, But ...

There's always the '$ No Object' crowd....*G*  And I wish them well, and hope you've got the space for the Trw-17, and the more power to you.

You'll need it...;)

I remember reading that same article back in '10; the 'pitch-shifting blades' instantly reminded me of 'prop wash' from light aircraft, hearing the 'pitch shift' as the prop is adjusted....having grown up the son of one who worked for Douglas Aircraft in SoCA....

Novel use of the tech; not for the average HT, no....😏

....though it does start to edge into 'He Who Need Not Be Named' sort of turf, what with concrete walls for drivers and an astounding level of confidence in the quality of his hearing and its' perfection beyond us mere mortals...

...and at the cost of the rotary... What if you didn't like it? *cringe*L*

WTH would it cost Now, given the improvements in 'circuit magic', acoustic materials and the app of active room eq, etc., ad near-infinitum....?

Reality...what a concept...*sheesh*L*

Thanks @wsrrsw: Thanks, I hadn’t seen that write-up on the TRW-17.

@uncledemp: Though "normal" recordings made in studios are limited in very low frequency content, some recordings made in very large "rooms"---cathedrals and churches, large theaters---contain very low (below 20Hz) information. That’s why you can hear the sound of the room itself (the dimensions of large spaces allow very low frequencies to propagate.). I have some EMI and Decca Classical LP’s in which the environment in which the recording was made is quite audible/evident---a HUGE space. I can only imagine what the ET TRW-17 would make them sound like!

@aldnorab: Some good questions. Here’s some answers to them:

1- Very true. That’s how I learned of the Magneplanar Tympani T-I’s (Gordon Holt’’s review of them---which was not entirely positive---had not yet appeared in Stereophile). In the Spring of 1972 I happened to visit a newly-opened hi-fi shop on the very day Bill Johnson was delivering and installing a complete ARC/Magneplanar system in the shop’s excellent sound room (Bill was a pilot and owned a plane, so flew himself and a demo system to new dealers who were located far from Minnesota). I made like a fly on the wall---keeping my mouth shut and my ears open, listening to Bill and Walter discuss all thing hi-fi. I got quite an education that day!

I had already heard the Infinity Servo-Static and Dayton Wright electrostatic loudspeakers, but was unprepared for the sound the ARC/Maggie system produced. Shortly thereafter I bought from that dealer (Audio Arts in Livermore, California, owned and operated by Walter Davies, as fine a man as I have ever known. He later created the Last Laboratories line of excellent LP and tape preservation products.) the same system: Tympani’s bi-amped with the ARC passive crossover and D-51 and D-75 power amps, an ARC SP-3 amplifying the signal from a Decca Blue cartridge mounted on a Thorens/Decca player. That was Johnson’s reference system, except he had brought along a prototype tonearm in development at ARC, which was never put into production. I remember it resembling the Weathers and Grado arms of the 1950’s and 60’s.

2- Prior to introducing the LFT-8, Eminent Technology had already marketed LFT models which were not hybrids: the LFT-3, LFT-4 (a pair of which I also own), and the LFT-6. Instead of a dynamic cone woofer, those three models had planar-magnetic woofer diaphragms, which were of course somewhat large (bass frequencies require drivers which have either large radiating surfaces---planars of course do---or considerable excursion capabilities---planars don’t---in order to be able to "move" enough air.

To make an LFT model of more modest proportions, Thigpen decided to use a dynamic woofer for the LFT-8. He readily admits the 8" woofer is the LFT-8’s weakness, but for those with a room big enough one could use the bass panels of the Tympani’s with the LFT-8 midrange/tweeter panels. Or, since the LFT-8 woofer operates up to only 180Hz, in place of it one could instead use a pair of the fantastic Rythmik Audio/GR Research OB/Dipole Subs (which---unlike "normal" subs---can be used up to 300Hz.). Or, get the new LFT-8c, which incorporates a new sealed dipole woofer. By the way, Magnepan has itself been working on their own dipole woofer for some time now, and it will eventually come on the market.

3- All drivers are made with compromises. Do the front-mounted magnets of the LFT driver cause diffraction? Remember, the more expensive Magnepans---the 20.7 and 30.7---themselves employ push-pull midrange drivers, with magnets front and rear. Which is worse: a small amount of diffraction, or a large amount of harmonic distortion? Only you can decide. ;-)

If you wish upon a star...

http://www.eminent-tech.com/index.html?fwd=LFT8.html

SOAF= Zero....unless vision-impaired..

Even then, with the 'hearing compensation' that's typically existing...

O, Lucky Man....;)

@avsjerry: That pic is with the front grill frame & cloth removed. With it in place, the LFT-8 looks no worse than do Maggies. Not pretty, but not horrible.

Would love to hear with my Acoustat Model X’s.  Over the years, I’ve tried probably ten subwoofers with them and have never found one yet that’s fast enough.