As he promised, Guttenberg reviews the Eminent Technology LFT-8c.

Damn Ric, you’re gonna scare off potential LFT-8b/c buyers!

Sure, an outright fanatic like Ric Schultz can concoct a Frankenstein LFT loudspeaker, but most audiophiles (including those reading this thread) are looking for a plug & play loudspeaker, not a complicated project. Heck, even building the Rythmik Audio/GR Research OB/Dipole Subwoofer is beyond the interest and/or capabilities of your "normal" audiophile. I found it to be relatively easy, and I’m no master cabinet builder.

The recommendation of the Eminent Technology LFT-8b/c was suggested as an alternative to the far more commonly known Magnepan planar-magnetic loudspeakers. In the opinion of myself and Steve Guttenberg, the LFT-8b is superior to the Maggies, only slightly higher in price to the clearly-inferior MG1.7i (I compared the two), and less than 1/2 the price of the MG3.7i. The 3.7i I have not heard, Steve has. Make of that what you will.

How would a set of 8b’s integrate with a swarm subwoofer system?

@peter_s: Very well. In fact, since the LFT-8b has limited response below 40Hz or so, it is an excellent candidate for add-on subs. And since the response of the woofer at 40Hz and above is unusually "fast"-sounding, it blends well with subs. I myself use a pair of Rythmik Audio F15HP subs (I bought the kit version, building my own 4cu.ft. enclosures), using them crossed over at 40Hz. I also built a pair of the Rythmik Audio/GR Research OB/Dipole Subs to use in place of the LFT-8b’s woofers, but that’s a story for another time.😉

The LFT-8b---having a sealed dynamic woofer for reproduction of frequencies 180Hz and lower---doesn’t suffer from the dipole cancellation found in full-range dipoles (such as Maggies). But an 8" dynamic woofer in a sealed enclosure---even one of the quality of that employed in the LFT-8b---can do only so much. Since the LFT-8b woofer is a monopole, there will be no discontinuity between it and a sub swarm also of monopole design.

Bruce Thigpen intentionally uses a higher-than-normal-mass woofer in the 8b (he in fact mass loads the driver), sacrificing the ability to play above 180Hz in exchange for better performance below that low crossover frequency. The LFT (Linear Field Transducer, invented and patented by Thigpen) magnetic-planar driver reproduces 180Hz up to 10kHz, with no crossover in that frequency band! That’s one major reason for the 8b’s unusually-high sound quality. Another is the LFT driver being of push-pull design (magnets on both sides of the Mylar diaphragm), in contrast to the single-ended Maggies such as the MG1.7i.

$3200 for the sound quality provided by the LFT-8b? You have to hear it to believe it!

There is no death......there is nothing to fear.

Here is a SUPER SIMPLE serious speaker. Buy a pair of the Lii Audio Platinum 10 inch full range drivers ($2200) and mount them on a four foot by 2 foot piece of multiply damped baffle and have four foot by 2 foot wings on the sides going back. Now you have a full range open baffle speaker that costs around $2500 for the drivers and wood and is 100 db efficient and when properly burned in and wired directly from your amp to the voice coil wires.....will sound incredible....You should get close to 40 hz in room with no eq. You could build a test baffle in one afternoon and start enjoying them while they burn in. My friend has the Silver 10s mounted on the above mentioned open baffle and he gets 40 hz flat in his room. He did mount an AMT on top with a copper foil cap to make it even better. His drivers are $1200. He goes to shows and the only thing he likes better at a show than what he has are the expensive silver Supreme Borresen speakers driven with 100K worth of stuff. He uses a tube amp he built himself. Plenty ways up the mountain of great sound.

You might want to check out the wild horn loaded cabinet that Decware designed for the Platinum speaker driver. There are sound bites on You tube. He does not wire directly to the voice coil wires.....he uses the junk binding posts on the speaker and probably another binding post on the front of the speaker (not good...he is not much of a tweaker). But his cabinet is way cool.

Ric is serious about cabinets. When he was building speakers using the BG NEO drivers and Rythmik/GR Research 12" woofers mounted on an open baffle, he made the baffle with 3 layers of MDF, Green Glue between layers.

I made my open baffle (W-frames for the OB/Dipole Subs) and sealed enclosures (for the 15" woofers) using one layer of MDF and one of Baltic Birch, with a layer of ASC Wall Damp between them. I braced the sealed enclosures with strips of Baltic Birch (two pieces of 3/4" x 1.5" glued together to make a 1.5" x 1.5" brace), one every 6" in all three planes (front-to-back, top-to-bottom, and left-to-right). Very stiff and non-resonant. With the Rythmik Audio servo-feedback woofers installed, I get the best bass reproduction I’ve ever had.

I had originally designed enclosures as per Danny Richie’s idea of doing a double-walled box, with a 1/2" space between the two boxes into which sand is poured. But with the serious bracing and the resulting size of the 4cu.ft. enclosures being 24" H x 18" W x 24" D (those braces eat up a lot of internal volume), I decided to use the Wall Damp means of absorbing wall vibration (the frequency of which---due to the bracing---is way above those the woofer is reproducing) instead. Using two different forms of wood---with different resonance characteristics---is another way to combat enclosure wall resonance.

I don’t have a table saw, so I hired a woodworker to cut all the wood for me, working off the diagrams I supplied him. He also had a CNC machine, so the cuts are very clean. The internal MDF walls are glued together, the outer BB walls (cut to size on top of the inner walls by myself with a router) just finished with clear lacquer. Looks European! I left a 1" space in the front of each H-frame and sealed enclosure for inset grills, like speakers had in the 1960’s.

I say all this to make the point that building the Rythmik Audio/GR Research OB/Dipole Sub---or even a GR Research or other brand DIY loudspeaker---is not beyond the abilities of younger audiophiles (no offense, fellow gray-hairs ;-). For the older or mechanically-challenged fellas, Danny Richie offers flat pack kits---and even fully-assembled enclosures and I believe completely finished speakers---via some woodworkers who collaborate with Danny, so it’s a path to champagne sound quality at beer prices worth considering.

But for a plug & play loudspeaker, can the Eminent Technology LFT-8b or 8c be beaten at its’ selling price? If your taste runs to dipole planar loudspeakers, I don’t think so.