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

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.

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...

@ricevs I bought of pair of Lii Audio's that someone else built with baltic birch plywood...without the baffle step filter network he had built with Dayton parts, I didn't like them. They were too shouty when connected directly to the amp. With the filter they were better...but ultimately I sold them and replaced with Tekton Lore...which I am quite fond of. I have a long history with single driver designs and on some recordings, they are remarkable....but I am now of the opinion that they need filtering for the rising response or DSP to handle it.

When Stereophile reviewed the original version it was kind of a disaster...John Atkinson is normally pretty nice about poor measuring speakers but this one just looked broken. A lot of time has passed and my question for Eminent would be how they addressed the super rough response, ringing, and rough spectral decay. 

https://www.stereophile.com/content/eminent-technology-lft-viii-loudspeaker-measurements

@seanheis1: Though reviewer Corey Greenberg loved the LFT-8 ("These are MIGHTY fine speakers, rivaling many well-known models at considerably higher prices. In terms of detail and midrange clarity, they are some of the most impressive speakers I’ve heard at ANY price. The LFT-8’s gave the impression of a very fast, natural-sounding speaker."), John Atkinson’s measurements of it were indeed pretty bad. Measuring a dipole planar loudspeaker is fraught with peril, the measurements not at all correlating with the sound the speaker produces. That’s why Magnepan doesn’t send out their speakers for review.

Something to be aware of: The LFT-8 Greenberg received for reviewed was the original version. Partway trough his evaluation, Bruce Thigpen send him a revised planar panel, which had it’s ribbon tweeter moved from the top of the panel to its’ middle. The LFT-8 then later had three other revisions made---a different woofer, tweeter, and cross-over. With one of the revisions came the 8a nomenclature, another the 8b.

John Atkinson knows how to measure a dipole...but I agree an average Joe would struggle to get the best possible measurement just like they would struggle to get the room and placement just right for that tiny sweet spot...reviewer gatekeeping is pretty severe with family owned hi-fi brands & really anything high end like Wilson/Magico...it's smart business.  

Magnepan measures poorly due to things like phase cancellation and a first order filter...it appears some Eminent speakers do the same and the top model uses DSP for some frequencies...but higher frequency beaming with planar designs can't be fixed.        

There are people that rip out the Magnepan filter & replace it with a DSP crossover to presumably level the response and time align the tweeter and midrange....to great satisfaction based on self-reporting....but to each their own.

This is not to say that one cannot love a speaker that has a highly uneven frequency response and ringing. Zu Audio would not exist if people didn't like what it did...including it's editorialization of the response and masking other frequencies.

Regarding Corey Greenberg, he did note a lack of coherence between the mid and bass panel. Steve Guttenberg noted the same. However, Steve Guttenberg noted an improvement in coherence with the DSP version...not surprising....but then he did mention he didn't like how the DSP changed the sound so he turned DSP off...so who knows...I have heard DSP sound terrible and I have heard DSP that is transparent...all about implementation and the technology used of course.