Eminent Technology LFT 7 !!

Awesome @riverdinaudio! I don’t think a pair of LFT-6’s ever made it to the West Coast (I’ve never seen a pair for sale here). My LFT-4’s were shipped to me from the Midwest iirc, and arrived in perfect condition (packed with a LOT of bubble wrap).

I eagerly await the introduction of the LFT-7.

The 8c isn't for me either @daytrader; no digital, thank you very much!

But there's a better alternative anyway: a pair of the OB/Dipole Servo-Feedback woofer system that Rythmik Audio and GR Research developed and market together. While the new ET "c" woofer is a dipole, that is all it has in common with the Rythmik/GRR woofer. It contains 2 or 3 (your choice) 12" woofers mounted in an open baffle frame. Unlike "normal" subs, it plays up to 300Hz. That enables one to use it in place of the stock LFT-8b woofer! Just leave the stock woofer disconnected (easy as it was it's own binding post). The plate amp that comes with the kit (yes, you have to build it, or have one of Danny Richie's cabinet makes do it for you. For a price, of course) has the most extensive range of controls on the market, including the option of a 180Hz 1st-order low pass filter, to exactly duplicate the filter used with the stock woofer.

And it's 100% analogue!

Actually, I should have said "to minimize the degree of comb filtering created" rather than "to prevent comb filtering." And then place the second panel with the midrange driver up against the side of the first pair on which is located its tweeter. That will create a sort of coaxial driver, in the horizontal plane at least.

When running dual LFT-8’s, the tweeter on one of the two speakers (per side) should be disconnected, to prevent comb filtering. The tweeter operates from 10kHz up, with a 1st-order high pass filter (and the midrange panel a 1st-order low pass at the same 10k). The wavelength at 10k is only 1.35 inches, much larger than the distance between the tweeters in two LFT-8’s placed side-by-side. A pair of stacked LFT-8’s is an interesting proposition, one on top of another rather than side-by side.

I have a pair of LFT-4’s, the half-sized LFT-6. And a pair of LFT-8b’s. I’d trade my two sisters for a pair of LFT-6’s.

@riverdinaudio, agree about the Maggie ribbon tweeter. I have a pair of Tympani T-IVa's, which contain it. I never though of using it in place of the ribbon tweeter in the LFT-8b, as that ribbon is used only for the top octave. When I get the time, I'm gonna place the T-IVa m/t panels beside the LFT-8b panels, compare the two tweeters. Thanks for the idea!

There are a group of guys on the Planar Speaker Asylum Forum who had removed the midrange driver from the T-IVa, replacing it with multiple NEO8 drivers (seven, iirc). Haven't heard them myself, but reports are very positive.

I failed to mention it above, but the GT Audio Works sub is nothing more than the GR Research/Rythmik OB/Dipole Sub kit installed in their own H-frame, not visa versa. Credit where credit is due! The sub came from the fertile mind of GRR's Danny Richie, a long-time proponent of OB loudspeakers and subs. When he learned of Rythmik Audio Brian Ding's new servo-feedback sub system, he thought mating it with an OB woofer (which are designed specifically for that application, different from those designed for non-OB use) would create a new SOTA sub/woofer, and got to work on the design.

The sub uses the Rythmik A370 plate amp, into which Brian Ding installs a dipole cancellation-compensation network (a simple single-pole/1st-order low-pass filter). Danny designed the woofer, which is the Rythmik 12" paper cone woofer optimized for OB usage.

@gstewtoo, great to hear from another planar fanatic, especially of the Eminent Technology stripe! Bruce's speakers are ridiculously under-acknowledged and appreciated, aren't they? I'm still hoping to eventually snag a pair of LFT-6, but until then my LFT-4 and -8b will have to do. ;-)

Did you do the x/o upgrades yourself? I would like to eliminate them altogether, and use my First Watt B4 x/o in place of the speaker level filters, but Thigpen's x/o's are not textbook designs: they employ driver-compensation elements that the B4 can't replicate. Still, just bi-amping them with the B4 should produce a worthwhile improvement.

Because both the GR Research/Rythmik OB/Dipole Sub and their standard sealed enclosure subs (the F12G in the case of GRR) employ the Rythmik Servo-Feedback system, the difference between the two is not as great as it would be sans the servo. Each has it's own strengths and weaknesses in comparison to the other:

Sealed provides more output, OB less room loading as well as dipole characteristics matching that of planar loudspeakers (not just out-of-phase cancellation to either side, but also equal SPL drop off at varying distances, keeping the speaker/sub balance the same at all listening positions.). Not to mention no sealed enclosure resonance issues!

THE sub for planars is the GR Research/Rythmik OB/Dipole Sub. This has been discussed on Audiogon numerous times in the fairly recent past, so I won't bore everyone again with the reasons why. ;-)

Yes, the swarm is a great thing, but an OB/Dipole sub is more appropriate for planar loudspeakers. No reason you can't have four of them!

Oh, you own LFT-6’s. I’ve located a pair, but shipping them is a problem for the current owner, and he’s on the other side of the U.S. from me. Road trip? ;-)

At one point I owned pairs of both Tympani T-IV AND T-IVa, which is just plain silly. Now it's just the T-IVa, LFT-IV and LFT-8b, and original Quads. Oh, and a pair of ESS Transtatics. A pair of LFT-6 and I'm all set. ;-)