New Eminent Technolog LFT-8C speakers

Loudspeakers
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The ‘8C is the fourth iteration of the OLD LFT-8, using push-pull mag-planar tweeter and MR drivers and a cone woofer system.. The latter is what is new, now being a different 8” cone in front with a 6-1/2” cone in rear that are both driven with a built-in amp that uses DSP processing.. The DSP is for mostly the woofer but can also apply a variable-frequency hi-pass filter to the amp driving the MR panel and a variable-but-should-be-0.6-millisecond delay to the panel amplifier to correct timing errors between the two different types of drivers.. Connecting the panels thru the DSP* is optional, but that’s the way I have it now.. The main issue Bruce solved with the dual-woofer system is that the earlier versions of the woofer were single-driver monopoles instead of dipoles like the panels.. Read…

and watch

Mine arrived yesterday, Sunday the 21st.. I already knew about this but was still a bit surprised at how DIY they would appear to a novice, especially since they include NO instructions. Let’s just say ‘some assembly required’; I had no trouble getting it done with virtually no help.

The sounds so far–that is, fresh out of the cartons–is just what I expected–at least 9 octaves of bandwidth, excellent rez and tonality, and a tallish, spacious soundstage.. What is audible already (to this slow-hearing music lover who is NOT a golden-eared audiofile) is the improved coherence of the music coming from this system.

The original feet are almost laughable–simply pieces of 3/8”-squarestock steel with some holes in them and painted flat-black; I’ve ordered the optional ($500?) stands which are MUCH sturdier and stable.. I’ve had these under earlier versions of the ‘8s and they are well worth the money.

Things are rather messy now, but I’ll post some pics soon,

(1) that is, IC cables from preamp to DSP/bassamp and then cables from the DSP to the main amp(s).

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2025Sep22_DSC1277_ '8Cs in_2000w
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One little problem–the M1200s have so much Voltage gain–30.5dB, which is only about 10dB too much, IMO–that I ‘have to’ run the the woofer gain full up, and I’d still like about 10dB of room to play with.. The BHK600s have switchable gain of 30.5 or 26dB, and the Atma-Shere MA-1s have 25dB, so those amps will give me 4 or 5dB of range.

They sound REALLY good–very high rez, nice tonality with the bass level, lo-pass-filter point, and filter slope all adjustable, and a VERY nice soundstage with some height.. I think I’ll reinstall my 3by5feetby6inches fiberglass panels on the front wall behind the speakers.

I’ll be changing the musicroom a bit the next month or two.. The two book- and CD-cases are coming out of the front corners and moving to the rear on the sidewalls, while the amps and CC speaker are moving about three feet forward and closer to the front wall; the loboy is departing the premises.(1) Then we’ll cut away the front six feet of so of carpet and level the front five feet of concrete floor.. All that will leave plenty of room in the front for a 3cm granite pad which will hold two or maybe three pairs of poweramps and somehow, the incoming ET LFT-12(new) CC speaker.. The angled corners will have plenty of room for my pair of GoldenEar SuperSub XXLs…

…which I’ll tune as real subwoofers that will be low-pass filtered at 40 or 50Hz, to reinforce and extend bottom-octave energy.

(1) If anyone close enough to Phoenix wants that lowboy, it’ll be only $100 retrieved by you.. I paid about $1300 for it IIRC.

PS. The red dots on the speaker panels are the targets for my laser-based Bosch DLR-130 Distance Measurer.. I carefully mount that (with the system’s rotational point ON the axis of the laser) on a foto tripod so that I can measure speaker distances.

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Neat setup, measuring tool is Kool… post away when its complete!

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While Bruce Thigpen has a bunch of planar speaker patents (mostly around optimizing the magnet structures to reduce the amount of magnetic materials used) and by all accounts some very good inventions over the years, I am very puzzled about the Eminent Technology speakers. The crossovers, or lack-thereof are very strange and there is broad overlap between the drivers causing all kinds of interference and nastiness.

This was the original LFT-VIII as measured by Stereophile.

94ET8fig03
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The LFT-16 that they measured had the midrange and woofer out of phase and even swapping the polarity showed a very non-optimized crossover with a broad peakiness.

I’m not sure if they have fixed any of this but some basic sane crossover work would vastly improve the performance of these things, as the drivers and system design seems very reasonable.

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

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Chris, I don’t know how things were(1), but today’s LFT-8C has the two panel drivers and the woofers in the same electrical polarity, and with the 0.6msec. delay applied to the panels, the three of them are in phase too, at least at some frequencies, which is better, I believe, than being in phase at NO audible frequencies.

These ‘8Cs sound significantly more coherently spacious and spaciously coherent than their predecessors did.. Fortunately or unfortunately, depending on one’s perspective, there are many useful attributes to tune in the DSP(2).. I’ve tweaked woofer level and low-pass point but nothing more…yet. There are two parimetric eqs accessible via the DSP’s control knob and five more accessable thru the app, which I do not yet have; I have an aversion to having outboard computers connected to my audio/video system.

…and they have a tall soundstage, something that’s very important to me. :grinning_face:

(1) I owned, played, and played with LFT-8s, ‘8As, and ‘8Bs, but all that was many decades ago.. The term ‘decades ago’ is easy for me to use truthfully, since I’ve been an audiofool for more than 65 years…and STILL no golden ears!!!…but I’m still a musiclover, and I try hard.

(2) I’m increasingly convinced that the more variables there are to refine the sounds, the more opportunities and degrees there are to thoroughly screw up the sounds.

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I’m still tweaking the bass controls; of course the level is adjustable, but when one adds the Lo-Pass Filter Point and the LPF slope, the number of combinations is amost infinite…AND…there’s a ‘rumble filter’ (what a quaint term…:slightly_smiling_face:) with a Hi-Pass-Point that’s adjustable for frequency and slope.. I’ve adusted all these to balance overall bass level, degree of warmth added to the upper-bass/lower-MR, and power handling.. I listen to big-orchestra Romantic-period Classical and film music, and there are BIG bass drums in that music, and those two, relatively small woofers in the ’8C can output only so much bass energy.. They are, after all, NOT SUBwoofers.. So…still tweaking.

The MR and treble portions of the music seem to sound better and better(1)–excellent rez, tonality, spaciuosness, soundstaging, instument placement and size, etc.. (Adding the Sound Anchor stands MAY have something to do with that.) One feature of the ‘8Cs that helps those characteristics is having NO filtercaps in the MR filter network(2), and I don’t plan to add any.(3)

Oh yes…these sound SO good that I’ve formally ordered a pair of LFT-6s from Bruce.. These are full-range…well, at least nine-octave…all-mag-planars that are a little bigger than the ’8s and have been discontinued for years(4); I’ll be adding a separate thread for those.

Meawhile, gorgeous music!!!

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(1) Try to remember while reading my drivel that I am NOT a golden-eared audiofile, I’m a slow-hearing music lover who pays attention when he wants to–and who usually is simply enjoying the music!

(2) The MR x-over is merely a low-pass choke.

(3) Said another way, I will not be adding a bass-blocking ‘protection filter’ in the digital processing.

(4) I as Two Jeffreys Audio in the 1980s was an Eminent Technology dealer, and I guess Bruce likes me.

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