I recently signed up for the V.P.I. Industries newsletter, and today received my first such. In it, Harry Weisfeld reviews a Grado phono cartridge, but this post concerns one of the speakers he listed as being those he uses to listen to music and evaluate recordings through. All but one are traditional dynamic cones/domes in a box designs, only one being a planar/dipole. That planar is the Eminent Technology LFT-8b. I'm pretty sure Harry could, if he so chose, have instead as his sole planar a pair of $6000 Magneplanar MG 3.7i's, or even $14,000 20.7's. But nope, he instead chose the $2500 ET LFT-8b, imo the greatest value in a loudspeaker on the market. I compared it to the 1.7i, and the difference was dramatic.
The low price of the LFT-8b works against it in the mind of audiophiles who equate price with quality and performance. But it’s more than just that; far more people own Magnepan MG1.7’s than LFT-8b’s (approximately the same price after Mye and Sound Anchor stands, respectively, are bought for each), many of them not even knowing of Eminent Technology. That’s a result of ET having far fewer dealers than Magnepan, and getting far fewer reviews. I believe many 1.7 owners, had they heard the Magnepans and ET’s side-by-side, would have instead purchased the ET’s. But ET exists like a cult-level band, known only by the hippest music lovers. Flying under the radar, so to speak.
The same is true of Music Reference (the RM nkj refers to directly above is Roger Modjeski, designer/builder/owner of Music Reference products. Roger designed the direct-drive tube amps for the Beveridge ESL’s, and now makes his own direct-drive tube amp/ESL loudspeaker with sub system, available for $12,000/pr). Roger is very much like Eminent Technology’s Bruce Thigpen, designing and making products offering ridiculous value, yet owned by far fewer audiophiles than those of more "trendy" companies, ownership of which carries with it more audiophile cache’ and bragging rights.
How many have compared an RM-9 or RM-200 against an ARC, Conrad-Johnson, Quicksilver, Jadis, VTL, Manley, Shindo, Cary, Lamm, Ypsilon, McIntosh, Allnic, etc. amp? Aside from Brooks Berdan, only Michael Fremer, as far as I know. Brooks had sold ARC when he was at GNP Audio, and chose VTL, Jadis, McIntosh, and, yes, Music Reference as his tube brands (along with a few others) when he opened his own shop. It was he who turned me on to both Eminent Technology and Music Reference, two of his favorite companies and product lines. Wise man.
Oops, left out Atma-Sphere! By the way, Modjeski is now making OTL amps himself, including those in his direct-drive ESL loudspeaker. No output transformer in the amp, no input transformer in the speaker!
A couple small corrections here. The Music Reference ESL Speaker System is $12,000 including a pair of ESL panels, a pair of bass speakers, and a bass amp that includes an active crossover (4th order Linkwitz-Riley, 100 Hz high pass and low pass). The direct drive amps are extra starting at $6,500. The speaker system and amps are custom built to order.
Yes, there aren’t any output transformers in the direct drive amps so technically it is an OTL. However, they put out 5000V. Not sure how many OTLs do that, so the speaker better be up for it.
I run the original Acoustat servos with Acoustat Model 2s with panels modified by Roger Modjeski (I also have Quad ESL with Atma-Sphere M-60s, but converting the Quad to be powered by direct drive). I augment them with a bass array of 4 woofers in a biamp set up. For Roger, the 100 Hz cutoff point is important (his ESLs cut off here), as he wants to avoid male vocals creeping in to the low end, which he has demonstrated to me on select recordings he has. That’s the main reason the LFTs and their 180 Hz cutoff aren’t in my system.
Thanks for the info and correction clio. 5000 volts! Beware, modifiers!! I bought a pair of LFT-4’s as an alternative to my Quad ESL’s, and it CAN be crossed-over to at 100Hz (or lower) from a sub, being a pure panel / no cone woofer design. I know Roger uses an 8" woofer in his sub, so am thinking his ESL may be an excellent candidate for the OB/Dipole Sub from GR Research/Rythmik. No offense, Roger ;-) . An 8" woofer can move only so much air, and the dual 12" woofer OB/Dipole Sub is really, really good, and perfect for dipole loudspeakers. I gotta sell some of my vintage drumsets before I can spring for the Music Reference direct-drive system.
Unfortunately Bruce won't sell the panels separately, which I can understand. As for active subs, I just can't get past the internal amplifiers they use. My Luxman M-02 might not be the be all end all in power, but for the 8" drivers Roger selected it's near perfect. The crossover is EQ'ed to 30 Hz which is enough for me.
The Rythmik A370 plate amp (the amp in the OB/Dipole Sub) is no ordinary amp. It is a well designed 370 watt class A/B analog amp, controlling the dual 12" woofers in a servo-feedback circuit. The front-to-back cancellation inherent in dipoles is counteracted with a 6dB/octave shelving circuit, providing response to below 20Hz at sufficient SPL for most music. The dipole operation of the sub works particularly well with dipole speakers for the obvious reason, as well as exciting one less room mode than monopole subs.
Clio, if you ever see an Electron Kinetics Eagle 2 amp at a reasonable price (less than $500 or so), consider getting it for your 8" woofers. It is a KILLER bass amp!
Bruce Frederick, I also used Xindak. Also liked it, but very much like the Audiomica Dolomit Reference cable I now have. Not biwire configuration. Using pure silver cable as jumpers. Powered by Hypex Ncore400 amps, with Vandersteen 2wq subwoofers making a world of difference to not only the low end but also freeing up the amps to make the mids and highs simply effortless.
I have a pair of LFT-8b's, I put them side by side and ran the exact same audio signal through both one at a time. I found one speaker to be louder than the other. Could anyone tell me what could cause this or how I could adjust them to correct this.
There is a reason Harry Weisfeld chose the LFT8B's for his planar choice. Bruce Thigpen, the designer of the LFT8B has been designing "out of the box" (no pun intended) audio for decades, just like Harry Weisfeld whom I would imagine has great respect and admiration for Bruce. Bruce, if I'm not mistaken, has 7 patents for his various designs and you can't say that about most audio designer. The LFT8B's have been around for over 3 decades and in all that time I believe he has made only one change to the design, the tweeter was changed to the same exact material that he uses in the midrange driver and extends out to 50K! In other words, he got it right the first time. It's simply a brilliant design. In my opinion, the clarity and transparency is unsurpassed at any price (as long as the equipment upstream is up to the task). When they are set up properly (easier said than done) they are stupid good for the money.
I bought a pair of the LFT8B's a few years ago and thought they were very good and as I look back at old photos of my system back then I can't believe how good they were with the mediocre equipment I was using (it was all I could afford then). Cambridge stereo amp and preamp which is good gear but not really considered high end by most. I thought I needed the 200 wpc that the Cambridge amp offered. I was wrong.
Like most audiophiles, after a few years of enjoying them I wanted to try something "better" so I sold them (big mistake) and bought some good box speakers. The speakers I bought were box speakers with dynamic drivers that cost about 4 times what the LFT8B's cost. They were different, that's for sure. They had more slam and socked you in the chest and maybe imaged a little more precisely and they were certainly fun but they lacked that certain musicality that the LFT8B's had and I missed that unbelievable clarity in the midrange and high frequencies. So, after about two years, you guesses it, I sold them and bought the LFT8B's again! I thought, if I liked them back then, I should love them now as my equipment has improved a lot over the years since I had the LFT's. I now own a Pass Labs XA30.8 stereo amp that only has 30 wpc class A and before you all start wining about that not being enough to drive that speaker, let me tell you, your wrong. Not only does it drive them effortlessly but it always remains supremely musical. The moral of that story is, as long as the amp you're pairing them with has a great power supply (like all the Pass Labs amps) with the ability to deliver enough current into a difficult load, properly, don't worry. That XA30.8 amp is a giant killer!
So that, in my opinion is why why Harry Weisfeld uses the LFT8B's. There are not many speakers out there that are that clean, clear and open sounding and transparent and revealing WITH the musicality that they bring to the party. The low Q woofer in that sealed enclosure blends beautifully with the midrange and tweeter as well. Hats off to Harry for hearing their special quality and the fact that they cost $2500.00 pair is simply a gift. Stupid good!
Scot, I went through a similar learning curve back in the mid-70’s. I bought a pair of Magneplanar Tympani T-I’s in ’73, but grew dissatisfied by their slightly opaque lack of transparency and missing bottom octave. In ’74 I replaced them with a pair of Fulton Model J’s, which cured both problems (the J’s had an array of six of the great RTR ESL tweeter, and a transmissionline-loaded woofer that went pretty deep). But I soon missed the qualities large planar loudspeakers excel at, and sold the Fultons, forever after a diehard planar lover and owner.
People continue to ignore the LFT-8, buying Maggies instead. I have nothing against them (I currently own a pair of Tympani T-IVa’s, though I don’t have a room big enough to use them), but compare the LFT-8b to the MG1.7i; if you have already bought a pair of 1.7’s, you’ll wish you hadn’t ;-). The problem is, ET doesn’t have many dealers, so one can’t easily audition them. Luckily, Brooks Berdan Ltd. had a pair (Brooks was a big fan of ET and Bruce Thigpen), where I heard them. ET has a money-back offer on the LFT-8, with I believe a 30-day audition period. I suppose the consumer has to pay the shipping, but to hear the LFT it might be worth it. Consumers without a dealer within 150 miles can buy factory-direct, at list price.
I owned Tympani 1Us, purchased right after they hit the market with rave reviews from HP and others. I set them up right next to my homebrew KEF/RTR speakers described here in 2017. It was no contest; my speakers blew away the Tympanis in every way. Not only were the 1s bass deficient but also the midrange was opaque and the treble was so lacking as to fail to reproduce primary tones in the hf range. Cymbals easily reproduced by the RTR ESL tweeters in my speakers were absent with the Tympani’s. I sold them within a week. This is no slur on modern magnepans with ribbon tweeters, just a comment on how far we’ve come.
Lew, do you remember J. Gordon Holt's reaction to the T-IU? He drew a line on a chart, representing what the speaker's frequency response sounded like to him. It looked like the side profile of the top of a single-hump camel: a midrange hump with the response above and below the hump falling off in both directions. Owners of the T-IU were not happy when the T-IA was soon introduced, incorporating changes made to correct that. The IU could NOT be updated to IA status.
Agreed. Magnepan kept at it though, the 3-panel Tympani line culminating in the T-IVa, a pair of which I now own. Though the two woofer panels don't do the bottom half-octave (30-20Hz), if braced (either to the ceiling or the wall behind the panels) make great bass above that. And their ribbon tweeter (present in the T-IVa, and in the current MG3.7i, 20.7i, and 30.7) is a real good one.
I've only heard the Maggies cum ribbon tweeter in audio salons or at hi-fi shows, but the improvement is obvious, for midrange and treble, in every way. I think I subsequently owned the Tympani IIIs, with the huge woofer panels sitting in between two outboard midrange/treble panels. But those preceded the incorporation of the ribbon tweeter. They were way better than the 1U but not as good as the Martin Logan CLS with which I replaced the Tympanis, once and for all. From then on, I was exclusively an ESL guy. To get back to the main topic, I have always been aware of the favorable reviews and opinions on the Eminent Technology speakers, but I am guessing that my earlier trauma with the 1Us might have kept me from giving them a try. Moreover, I was not aware of their tube-friendly impedance character until reading this thread. I would have thought they were like the Maggies, not at all well suited to tubes.
Yup, ESL’s are IT for transparency imo. I have QUAD ESL’s, Stax phones, and a pair of ESS Transtatic’s with three of the RTR ESL tweeters, I’ve heard the big Soundlabs, and had I the requisite space and funds would have a pair of them too!
The impedance modulus of the LFT-8b is a good point to bring up. Thigpen says he could give the speaker any impedance he wanted, and chose 8 ohms. The LFT panels themselves are 11 ohms (and mostly resistive in nature), and may be bi-amped separately from the woofer (two sets of binding posts are provided).
The earlier full-range LFT models (LFT 3, 4---which I also own, and 6) are 4 ohms, like Maggies. The 3 and 6 are bi-ampable (at 400Hz, I believe), so a tube amp could be used with a big ss amp for the bass.
The LFT driver is much more robustly-built than the somewhat-garage-ish construction of the Maggies. The substantial metal driver frame is bolted into a cutout in the solid oak speaker baffle, whereas the Maggies have no metal driver frame, the Mylar being merely glued (and stapled?) onto the MDF (yuck) frames. The LFT is also a push-pull design, one reason listeners find it to be a very low distortion-sounding design, closer in sound to an ESL than to the Maggies.
I’ve never owned Magnepan Tympani’s but I did own their 3.7i’s for 3 years and really thought they were a great speaker. I also tried a pair of their DWM woofers and that was a fun speaker system. lewm spoke highly of their ribbon tweeter, I thought that true ribbon tweeter was one of the best tweeters I had ever heard, the high frequency extension on that tweeter was insane. My room was not as big as I would have liked (17’ x 12’x 8’ ceiling) but after much trial and error (mostly error) I finally found the “right” spot and then they loaded the room amazingly well. The right side of the frame was only 16” from the wall to the right of the speaker and to my surprise and delight it worked. I have always wondered what they would have sounded like if I could have got them 2 - 3’ from the side walls? I have noticed a lot of guys on this forum comparing the LFT8B’s to the Maggie 1.7’s. I now own the LFT8B’s and prefer them over the 3.7i’s, I don’t think the 1.7’s are even in the same ballpark (other then the price). In my opinion, there are very few speakers, regardless of price, that can rival the LFT8B’s.
In the LFT driver, Bruce Thigpen found a solution to many of the shortcomings audiophiles have long considered Maggies to have. It's too bad more of them can't hear the LFT-8b, buying the 1.7i not knowing what they could have for only a few hundred dollars more. Brooks Berdan carried the ET speakers as his only planars, but made a lot more money selling Wilsons ;-) .
Scot: "been around for over 3 decades and in all that time I believe he has made only one change to the design".
I'm not an authority on the ET speakers but if they went from LFT-8 to 8a to 8b then I imagine there must have been two changes sufficient enough that Thigpen made a model change. And there could have been minor changes not in themselves warranting a model change.
But I think your basic point that the design survived more than 30 years with minimal changes speaks to the brilliance of that design.
I'm not in the market today, but if I am again I will certainly consider the ETs, thanks to bdp's posts along with others.
Yes, the "a" update addressed issues with the ribbon tweeter's x/o (but not the tweeter itself), the "b" the 8" dynamic woofer.. You’ll notice that the LFT (Linear Field Transducer) magnetic-planar driver itself---which handles frequencies 180Hz through 10kHz, with no cross-over---has remained unchanged for over 30 years!
With the Covid stay at home order in MI I decided to play around with the .6MH inductor. I tried the new Jantzen copper foil in wax 14 gauge, which is all the rave. Sadly, it thinned out the mids with maybe a slight increase in detail.....btw I hooked them up in both directions and they were worse than Bruce's stock 18 gauge magnetic wire air cores which are very good. I debated on ordering the 12 gauge copper foil in wax but decided to go with the Erse XQ 14 gauge perfect lay air coiled inductors. I'm glad I did as the moment I hit play the mids sounded rich and full like a good tube amp. The detail was all there and so were the highs. I did A/B Bruce's inductors and easily identified the Erse's every time.....by the fat juicy midrange. If you have a large room and are looking for more meat in the midrange than the Erse's are the ticket. Funny how the change in wire gauge(DCR) can make such a big difference in the mids. I think the inductor switch is just as significant as changing the 470uf and 4.7uf cap.
Thanks @brucefrederick. I myself am considering sending the LFT-8b x/o schematic to Danny Richie at GR Research, seeing what he recommends as an upgrade. One can send him a loudspeaker for a free complete evaluation (he measures the speaker, including spectral decay---aka waterfall plot, phase relationship between drivers, frequency response, both on-axis and off, etc.) but the ET doesn’t require that, just upgraded x/o parts.
I read through many threads regarding the copper foil wax inductors before pulling the trigger. Actually Danny was a fan of Erse inductors FWIW. The Erse’s are a stock item at parts express and cheaper than the copper foil in wax . I forgot to mention that the ET’s sound a lot fuller at low volume levels..... also the new coils tamed the slight harshness in the treble with female voices in many of my cd collection.
Thanks again Bruce. Say, where inside the woofer bin is the x/o located? I haven't removed a woofer to have a look inside, though I have the parts for the "Davey" mod (to remove the woofer's resonance in the 1200-1500Hz range), just a cap and resistor.
I am also considering moving the x/o to the top of the woofer bin, right behind the LFT panel. Shorter runs of wire (maybe silver) soldered onto the driver terminals, eliminating the stock spade connectors.
the crossover is mounted on a cross brace(L to R) maybe 8" back from woofer opening. I replaced all the caps and have no resistors in the crossover since I am using the hi setting on tweeter. I would just replace all the caps while the hood is up.
I did try bi amping during the stay at home order and maybe noticed a little more clarity and less smearing of nuances and detail. Overall I think bi wiring gives me more of an improvement than biamping. I guess if covid comes back in the fall I'll try an outboard crossover as I have loss some real estate inside the woofer cabinet with the large sized film caps. Hats off to Bruce Thigpen for putting up with me as I play around with his genius design. Every email has been most pleasant and gracious.
Likewise Bruce, every time I have spoken with BT on the phone he has been very relaxed, not like he is trying to get off the phone as soon as possible. In my opinion, to realize the full benefits of bi-amping requires the employment of a filter on the inputs of each power amp, to keep the bass out of the m/t amp and drivers. As the x/o is a fairly simple symmetrical 1st order at 180Hz, that can be accomplished with a single cap on the input jacks of each amp, though a means of balancing the two amp’s gain is still required. A volume control on one of the amps (the bass amp being a good choice) works fine.
Has anyone tried to run two separate sets of speaker wires from a stereo amp to the two sets of binding posts on the LFT8B’s? My dealer says this makes a huge difference. Right now I’m using one set of speaker wires with the same wire for jumpers with great results. Thank you.
I’ve run my LFT8b’s (and prior to the tweeter upgrade as 8a) bi-wired and bi-amped.
The bi-amp configuration was using 4/5ths of a Sunfire Cinema Grand. Kimber 4VS on top, 8PR on bottom. Have run bi-wire with the same wire combo from a pair of Cary SLM100 mono amps (both with KT88 and EL34). Currently running single wire with the 4VS from the Cary’s with 4VS as the jumper and EL34s. With the Sunfire there was a subtle but appreciable difference in bi-amping but that was just having brought more muscle to the table. Never did a bi-wire with the Sunfire.
Ultimately I heard no significant difference between bi-wire vs single on the Cary’s. Did compare the 4VS by itself vs the 8PR. The 4VS ultimately had better synergy in the system.
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