Steve Guttenberg finally reviews the Eminent Technology LFT-8b loudspeaker.

@ledoux1238: I myself am opposed to the proposition of subjecting the output of analogue sources (phono, reel-to-reel and cassette tapes, FM tuner) to digital conversion, so won’t be getting the 18LS.

However, for those wanting one of the other advances of the LFT-8c and upcoming 18LS---that of dipole woofers in place of the 8b’s monopole woofer, there is another route available: just use separate dipole woofers, leaving the LFT-8’s woofer disconnected.

A dipole woofer system has been in development at Magnepan for quite a while now, and is reportedly about to be introduced (price not yet known). And then there is the Rythmik Audio/GR Research OB/Dipole Sub, which is two or three (your choice) 12" free-air woofers installed in an open baffle "frame" (@ricevs mounted them on a flat open baffle---3 layers of MDF!), the woofers powered by a servo-feedback plate amp. The plate amp controls include those for phase/time-alignment for woofer/loudspeaker mating, and of course output level (again for mating with the speaker), x/o frequency and slope, 1-band EQ, etc,., but accomplishes those jobs electronically, not digitally. It’s a great bass system, but is available only as a kit. You can get a CNC-cut flat pack that is a breeze to build (just wood glue and clamps, finishing of your choice) from a Canadian woodworker connected with GRR, and he will even build and finish the frames if you pay him.

And if you have the room, you can use the two bass panels of the Magnepan Tympani’s as woofers for the LFT-8b. They won’t play as low as the OB/Dipole Sub, but with enough power (and bracing) will get down to the low-30’s. Harry Pearson’s favorite bass reproducers!

@mijostyn 

As a former Tympany user myself just what are you doing now? The system you described above? 

Yes

Harry Pearson’s favorite bass reproducers!

I thought the Tympany were OK at the very bottom, not great. BUT, at the time I owned them, I was a recording engineer. Perhaps my perspective was colored by the awesome low end in some control rooms. OTOH, the Maggies' midrange and top were sublime.

Properly setup and configured in a good room, the LFT-8b, as I mentioned to Bruce, are "Merciless on bad material and sublime on well recorded."

@bdp24 I convert everything to 24/192 and RIAA correct the phono stage in the digital realm. I use digital crossovers, EQ and room correction to amazing effect. You have no idea what you are missing. But, I understand the purist approach. I drive an old 911. I have own new ones and do not like them, too darn refined. 

@ieales , You are not imagining anything. The bass of the Tymps is flabby at best. In total I think the 20.7 is a better loudspeaker. It still has less than optimal bass.

You are 90% of the way there with your speakers. IMHO your next move should be to disconnect the woofers in the speakers and build four 10 or 12" passive  subwoofers and space them evenly out on the front wall flanking the ETs. I would drive them with two amps and keep the channels separate, not mono. The crossover point I believe is 180 Hz. If you use a steeper slope (10th order) with your digital crossover you can safely push the crossover point down to 160 Hz. Time align everything and your bass energy will simulate a live performance. I use my old JC1s for subwoofer duty but I use to use a pair of QSC  commercial AB amps to great effect. Much less expensive. Dayton and Parts Express make incredible subwoofer kits at great prices. You can build for 12" subs for less than the cost of some commercial 12" units. Their drivers are absolutely top notch. I use 8 of their 12" Reference HO DVC drivers in my new subs. Each enclosure gets two drivers. I will be publishing the photo history of their construction on Imgur shortly.

@mijostyn Back in the mid to late 80's I had Tympani 4's. The earlier version where the 3 panels did not separate.

I converted my garage with advice from the Winey's to have one wall built on a slight angle to eliminate parallel walls. I then installed 2 layers of 1/2" drywall that were glued and screwed to the studs with glue between the layers along with 3 sets of headers between each stud location. The headers were about 20", 45", and 72" approximately above the concrete carpeted floor.

The amplifier for the bass panels was a Levinson ML-3 with dedicated 20 amp circuits for each of my 3 amps I was using at the time.

The bass performance was rock solid that it's equal I have never heard.

Describing the bass as flabby leads me to believe you have not heard the true bass potential of this speaker.

I recorded my Gretsch drumset (with a 26" bass drum) with a pair of small capsule condenser mics plugged straight into a Revox A77 reel-to-reel, using that recording to scrutinize and evaluate the sound of loudspeakers. For years the Magnepan Tympani bass panels came closest to replicating the live sound of that bass drum of all loudspeakers I auditioned: freedom from bloat (caused by driver "overhang"), percussive impact (i.e. attack), tonal timbre, texture, etc. For the sound of my Paiste 602 cymbals, it was ESL and ribbon tweeters.

The sound of a bass drum (even a 26" one) is more mid-bass than deep-bass, but those Tympani bass panels were very, very good at mid-bass. The sound of open baffle/dipole woofers is the closest dynamic driver equivalent to planar bass I’ve heard, the sound of the Rythmik servo-feedback subs second. For context, I own a pair of transmission-line loaded KEF B139 woofers (used by David Wilson as mid-bass drivers in his original WAMM loudspeaker), and owned Infinity RS-1b loudspeakers in the past, which had woofer towers containing six 8" servo-feedback controlled woofers.