Eminent Technology LFT 7 !!


Not a missprint!  LFT 7 was the LFT 6 with additional bass panels. The bass panels had 3 bass drivers per panel.  4 panels total.  Would like to hear them or purchase them.  
61eebd42 ef5f 470e a8c1 7b2099ea77c5riverdinaudio
I’ve never heard of the LFT-7. They’re not mentioned anywhere on the ET website (including the company's product timeline list), though the LFT-III and LFT-IV (which I own) are. Where did you learn of them?
At Eminent Technology website select Product History.  First production of LFT 7 was 1989.  Since the LFT8 was also released in 1989 I suspect very limited production of the 7.  
Well I'll be darned! You are of course absolutely correct, I don't know how I missed it. There were only 300 pair of the LFT-IV made, so when I found a pair I snapped them up. The LFT-6 is 78" tall, 18" wide. The LFT-IV is also 18" wide, but "only" 56" tall. The LFT-III adds two bass drivers to the LFT-IV, and is 27" wide, so I imagine the LFT-7 might also. 78" tall by 27" wide---a fairly substantial loudspeaker!
Exactly!  I found my LFT 6's in Texas and consider it one of the great purchases of my audio life.  Currently remodeling my primary audio space to better allow rotation and display of my speaker stable.  Magnepan's are great.  The LFT's are greater.  More of everything and no compression.  First time I heard the LFT 8 I cried.  They gave me everything the Maggies held back.  Still love to rotate my Magnepan 1.7s in for couple of weeks. Will always regret selling my Tympani IVa's.   And do not miss a chance to audition the 3.7s.  WOW!
I have given up on owning a pair of LFT-4s.  
Just received a response from Bruce Thigpen on my LFT 7 inquiry.  He says only 3 or 4 pair made and all went to Asia.  Darn!

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. ;-)

@riverdinaudio Would you describe the difference between a LFT 8 and 6?

     How about using your LFT 6 and using a high quality 4-sub distributed bass array (DBA) system like the Audio Kinesis Swarm reviewed below?

https://www.theabsolutesound.com/articles/audiokinesis-swarm-subwoofer-system/
     
     If you have the space to position these 4 relatively small, 12"Wx14.5"Dx28"H, subs with 10" aluminum long-throw woofers asymmetrically around and facing your room perimeter walls, I'm fairly certain this high qualitybass system would be an excellent solution paired with your high quality Eminent Technology LFT 6 main speakers. 
     I've used this bass system for about 5 years now, initially with a pair of Magnepan 2.7QR main speakers and currently with a pair of 3.7i for both music and with Oppo 105 and 205 Bluray universal disc players on 5.1 surround systems for HT.
     The 4-sub  DBA concept was first discovered through scientific research and experimentation somewhat simultaneously by acoustic experts such as Dr. Earl Geddes and Dr. Floyd Toole and then further developed by audio industry members such as Todd Welti of Harmon International and Duke Lejeune of Audio Kinesis. 
     This bass system concept implementation results in bass performance that is near state of the art in virtually any room and with any pair of main speakers, even those generally considered too fast and detailed to integrate well with conventional dynamic cone subs such as planar-magnetic and electrostatic panel type main speakers.  With 4 subs operating in concert, the bass extends down to 20 Hz +/- 3 dB, is as powerful and dynamic as the source content dictates, is very smooth, fast, detailed, with a sense of ease quality that is very natural on all genres of music and integrates seamlessly with any pair of main speakers. 
     You might reasonably think I'm exaggerating but I really don't think that's possible given the extremely high quality bass this 4-sub DBA system reproduces in my room and I believe will also reproduce in your system and room.  It's fairly expensive at about $3K, which I rationalized as about the same price as 2 high quality subs, but it's also a complete kit that contains everything you need except the speaker cables (4 subs, 1,000 watt class AB amp with volume, cutoff frequency, limited equalizer and continuously variable phase controls.  Each sub comes with conical spike footers and a port plug for operating in your choice of ported or sealed mode.  I believe AK still offers a 28 day free in-home trial period that takes almost all the risk out of an audition, too. 
     I found the attached Absolute Sound review of the AK Swarm above to be very accurate and will give you a good description of what to expect in your system and room.  I consider this the last sub system I'll ever need because I'm certain it will perform very well even if I move or change main speakers.
     You can check out my system pics on my profile if you're curious about how they look and are positioned.  The current pics are my former system with the 2.7QRs.  I'll be posting updated pics in the next few days with the 3.7is, $3K in new GIK room treatments, a new OLED 4K hdtv and a few other new components.

Best wishes,
    Tim

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!

Yes I believe in the Swarm bass array.  I currently own all components, cabinets made, for 4 Dual driver GR Research Servo Subs modeled after the GT Audio Works system.  So assembly will begin shortly.  My main listening room is 22x53x10 and is being remodeled.  I decided to go this way only because I have always wanted to experiment with servo controlled bass drivers and the cost to do so has become realitively reasonable.   I am not tied to OB/Dipole for bass but it is possible.  The PAP Quintet 15 proves that.  The Linkwitz Lab lx521.4 proves that.  For sub bass closed box is best to my ears.  Tastes varies.

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!

Hello riverdinaudio,

      I have listened to numerous high quality subs including dipoles but have never listened to OB or any GR Research subs.  My only experience utilizing 4 subs in a distributed bass array (DBA) configuration is the Audio Kinesis Debra 4-sub complete DBA kit system I bought and installed about 5 years ago in my 21'x15'x8' room.  This system is identical in price, sub amp/controller utilized and concept to the AK Swarm system except the Debra subs are more rectangular at 12"Wx14.5"Dx28"H.  
     I initially used Magnepan 2.7QR 3-way 6'x2' dipole panels as main speakers with no room treatments, DSP room correction or EQ and ran them full range (35-20K Hz) with all 4 Debra subs operated in mono, without the port plugs and a 40Hz cutoff frequency setting, so all 4 subs in mono and  ported configuration operating between 20 and 40 Hz.
     This setup provided what I consider near sota bass performance in my room that was fast, smooth and detailed enough to seamlessly integrate with the 2.7QRs while still providing the powerful deep bass impact and dynamics I felt they lacked.
     A couple months ago I upgraded to a pair of Magnepan 3.7i main speakers, which are the same size and 3-ways but have the true-ribbon treble transducer instead of a quasi-ribbon transducer, and fully treated my room with $3,500 worth of custom installed GIK room treatments.  You can view my recently updated system pics to view the results.
     Long story short, the true-ribbon treble section and other 25 year newer technology of the 3.7i main speakers, along with the room treatments, significantly improved the overall detail, sound stage imaging, naturalness, quality, realism and overall enjoyment of my system. And I  perceive the sota bass performance and seamless integration with the new 3.7i main speakers provided by the 4-sub DBA system as even more  impressive, which I didn't think was possible.
     So in summary, I'm stating that I'm thoroughly convinced of the 4-sub DBA concept's effectiveness in my room and believe you'll be thoroughly convinced if you deploy one in your room.  However, I'm not stating that 4 high quality GR Research/Rhythmik OB or servo-controlled sealed subs wouldn't perform and sound equally as well or better in a DBA confguration, because I've never heard them and just don't know.

Best wishes,
    Tim
Damn Tim, 3.7i's and the Debra Swarm. I would without hesitation take that over the 3/4 million dollar Wilsons. A lotta loot left for music!
Hello bdp24,
     
    Yes, the 3.7is with the Swarm are extremely good and a real bargain. Think of the 20.7s with better bass and dynamics at half the price. I've heard the 30.7s and don't claim the 3.7i/Swarm combo is quite that fine, or probably as fine as the $750K Wilsons which I've not heard, but it's definitely a close enough approximation to the 30.7s from my perspective, especially at less than 1/3rd the price.
    I went on a bit of a splurge in addition to the 3.7is and GIK room treatments. I also bought an LG 77" 4K OLED hdtv, pre-owned Levinson 326S preamp, Oppo 205, Lumin D2 dac/streamer and a 20 TB Synology hard drive that came loaded with 20,000 hours of music of multiple genres (rock, blues, R&B, jazz, folk, country and classical) that's all on my LAN and controlled by Lumin software on an iPad. It functions and has a GUI very similar to JRiver.
    I've chosen not to feel guilty and would think I died and went to heaven if I didn't have to completely pay for all of it to the last penny. But this is by far the best system I've owned to date and the system I receive the most enjoyment from on a daily basis with music and HT. So, I have absolutely no doubt it's all been worth it and have zero regrets.

Enjoy,
Tim
Interesting... sorry I missed this thread earlier.

I got a pair of LFT-VIs in 1994 or so and used them as my main speakers until I moved across-country in late 2006.

From 1981-1994, I cycled through Acoustat 2s, 2+2s, MG-IIIAs (Still the best highs overall in my setups!), 1+1s, PK R&D mods to the 1+1s, and original CLSs. Sometimes I used various fill-in speakers as gaps between selling and buying occurred and I filled those gaps with SMGs, MG-Is, MG-IIs, and Spica TC-50s (still have them!).

While all of the top planars above had their pros and cons, I found the LFT-VIs to be the best overall mix... not quite as detailed as the best electrostatics, but very close, not as good of highs as the big Magnepan ribbon, but not far behind, while not a single-driver electrostatic, with careful positioning they equaled the coherence of those speakers and the TC-50s, AND more dynamic than any of the other planars.

Before I moved, I’d already gotten the panels to do a mid-woofer rebuild (2 mid drivers had trace breaks) and looked for a fill speaker to use in the apartment until after we bought a house there and I had the chance to do that rebuild after we got settled. I found a good deal on some Gallo Ref 3A’s which were ok, but the mid-to-woofer transition was not as good as the full-range or otherwise coherent speakers like the LFT-VI. THEN I found a GREAT deal on a pair of LFT-VIIIs and got them... and they quickly replaced the Ref 3As. We moved into the house, I used the Ref 3As in the smallish downstairs ’temporary’ stereo room, and put the LFT-VIIIs upstairs for when I got time to setup that room.

Before that happened, I found another great deal on a pair of LFT-IVs and jumped on that. They went into that downstairs ’temporary’ setup in 2007-2008 and are still there now, a couple of crossover upgrades and lots of system changes later and sounding better than ever. AND I use the Ref 3A just away from the corners with a resistor across the woofer terminals as a bass damper... works!

Back to the LFT-VIs... The LFT-VIIIs (also with upgraded crossovers) are sounding great in that upstairs room. I’m working hard to retire mid-next-year so I can do that LFT-VI rebuild. BUT to the subject of this thread, I found a pair of mostly dead LFT-VI’s and got them for a good trade in 2009 or so. The dead panel drivers on my original LFT-VIs were the mids on 2 of the mid-woofers, so I figured that the 6 pulls from the LFT-VI rebuild would supply sufficient drivers for the deaders. BUT when I reached out to Bruce T at ET about using them to construct LFT-VII’s, he suggested getting 6 woofer only panels, similar to what they used in the old LFT-III outer panels, as that’s what they used on the original LFT-VIIs. So I did. MAYBE a year from now, everything willing, I can update y’all on how they worked out. Will be bi-amping them with separate amps for the woofer panels... and yes, if I need more woof, I’d consider some of the dipolar cone drivers like the GR Research ones mentioned above, I’ve heard a number of good dipole cone-drivered woofers/subs since 1980 or so and suspect they’d be the best overall match to the LFT bass presentation.

Greg in Mississippi

P.S. The LFT-VI’s got Sound Anchor bases (also on the LFT-VIIIs) and upgraded crossovers too along with Dynamat on the non-driver portion of the diaphram panels. All were well-worthwhile, though the Dynamat is way ugly!

@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.

As of last week my Eminent Technology stable is a pair of LFT3, pair of LFT6, 4 sets of LFT8 and two new LFT 8 panels.  My current project involves using the LFT8 panels with a Magnepan True Ribbon tweeter and GR Research Servo Sub stack.  Also working on an improved support for the LFT3.  How wonderful it is to find kindred spirits.  The Magnepan Ribbon tweeter IS without equal and I never have understood why people do not use it instead of complicated tweeter line arrays.  Magnepan will sell you a pair!
Greg, you made my mouth water with your saga.  More power to you!  I do belive that once one gets to 100Hz a correctly damped cone driver is the only way to go.  My Audio Artistry Beethovens have 4, 12 inch equalized woofers per side below 100Hz and it is a revelation of what true foundational bass is.   Hopefully, mag
...nepan will someday complete their plan to blend quasi-ribbon panels with equalized cone woofers.  Currently called the Condo 30.7.  But that is a another thread.  Back to my recently acquired LFT3s.  The previous owner suggested they were best at lower volumes.  I will soon know for sure.  The LFT6 may or may not need bass assistance depending on taste.  As a long time Magnepan owner the LFT6 bass was fine for me.  

@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.

At the 2019 Capital Audiofest I looked into the back of the GT Audio Works woofer stack and realized i could build my own for pennies on the dollar sine they are GR Research re-badged.  Pleae understand, the GT Audio Works system is a work of art and love.  I am a fan!
Many years ago I used the Magnepan 60" ribbon tweeter with the BG Radia 75" ribbons and generic sub.  Could never get it to blend and at the time my reference was a Magnepan MG20.  Even Magnepan had trouble blending their tweeter to there original wire on membrane design.  

I have a beautiful set of LFT-VI in my office paired with a two smaller SHU Subs. Works well enough,  played occasionally.  I have a minty NAK deck, too. I should play this stuff, not try to keep as museum pieces.   :) 
It is all too easy to get distracted from this hobby.  Start listenning at low levels, if you can, as long as you can each day.  Tidal steaming has revitalized my daily listening.  
I prefer silence in work, music occasionally.  I get all the listing I wish at home. :)

Sorry for the slow response, busy couple of weeks at work.

@bdp24, was it obvi that I love ET speakers? I’ll have to try to hide that better!

I did do all the xover and panel upgrades myself, if anyone is interested message me and I can send you a link to my ET Speaker folder on my Google Drive space and you can see the upgraded xovers for the IVs, Vis, and VIIIs along with the Dynamat on the LFT-VI panels. One thing that made the upgrades work on the IV’s and VI’s was being able to use the now unavailable Northcreek Audio 100uF and 200uF polyprops. I should have bought some additional 100uF when they still had them! I used these to replace the 470uF electrolytics in the originals.

While there are other caps in the 47uF-100uF range now available that will likely surpass them in performance, their price/performance was very good back in the late 1990’s / early 2000’s and an upgrade over the Solen that were the standard back then. Today I’d have to spend time looking over the Humble Homemade HiFi reviews along with scanning PCX and Soniccraft to see what’s available, likely a lot of good choices today (and great ones if you want to spend real $$$$$). A quick glance suggests the Auricap XO 100uF could be a good contender today, but upgrading a pair of LFT-IV/VI/VIII 470uF electrolytic caps would be a $1000+ purchase!

On the LFT-VIII xovers, there was some chatter on AudioAsylum about leaving out the 470uF in the midrange leg, so I did that there… no issues after running them that way for 14 years, knock on wood!

My read of the LFT-IV, VI, and VIII xover is that you should be able to duplicate the basic mostly 1st-order xover configurations with the B4 while retaining Bruce’s passive compensation networks directly on the drivers. Takes more good amps than I have, though! The LFT-III original xover was a bit more complex with some higher-order slopes, discussed at length in the IAR review. Since Bruce went to all 1st-order xovers for all speakers after that (except for the LFT-VIII mid-panel highpass where I believe the C6 2.2uF cap is there to compensate for a top-end rise in those panels), I wonder if he changed the LFT-III xover in the later ones.

BUT as you said, just biamping them with the bass-mids xovers at low-level before the amps and bypassing the in-speaker passive components will make a significant improvement even if you don’t go all the way to 3-way biamping. AND I never understood Bruce’s recommendation for the biamping split on the LFT-VI between the bass/mid and tweeter… bass – mid/tweeter makes more sense to me. AND that’s how he configured the LFT-III/IV and LFT-VIIIs, so not sure why the LFT-VI is setup differently. I guess I should ask him.

@riverdinaudio, I love your LFT speaker/driver collection and look forward to hearing about your experiments. I’ll keep your comments on the driver usage below 100hz in mind. My thought is to use the LFT-VI+VI bass panels to as low as they are effective… I’m guessing 40-50hz, maybe a tad lower. Then eventually cross over to a dipole cone sub setup to take it lower, likely something from GR Research.

One non-speaker revelation that has significantly improved the bass quality and extension of my setups in ways I didn’t expect and couldn’t imagine was using UC pair buffers on my DIY’d-ish DAC setups. I use an Allo.com USBBridge Signature as an I2S endpoint and feed either very modified versions of their Kali DAC or Ian Canada’s FiFoPi/DAC/output stage combos. In the last year or so I added a final buffer pair of 325F Ultracaps to the 2 DAC/interface rails (2x5V for the Allo Kali, 2x3.3V for the Ian Canada FiFoPi/DAC combo) and a pair of 3000F UCs on the 5V to the USBBridge Sigs. IF you DIY your digital gear and can handle the UCs safely (they will source welding-level current if shorted), I highly recommend this. Revelatory in many ways, with the bass improvements just a part of the overall jump upward.

BTW, does anyone have the IAR LFT-III review scanned? I have the hard-copy, but if someone has it scanned and can forward, that’ll save the scanning effort. Just lazy, I guess.

@riverdineaudio, really looking forward to your reports!

Greg in Mississippi

P.S. I’ve been an ET enthusiast since before he made speakers, getting an ET-1 tonearm not long after they first came out, upgrading it to an ET-2 when that became available, and now having 2 ET-2.5s.

@bdp24 ,

I think you found you're ' golden thread'
@slaw, ain't it the truth! Damn, @gstewtoo's post today has me feeling like a kid on Christmas morning. A lot of info to take in and digest, and then employ.
Just saw this LFT-VI pair plus bass modules from LFT-VIII's listed on EBay for $2,500 USD earlier this week:

https://www.ebay.com/itm/Eminent-Technology-LFT-6-Linear-Field-Transducer-Planar-Magnetic-Speakers/3...

They went pretty fast, 2-3 days.

I personally consider the price VERY fair... when I bought mine back in the mid-1990's, I paid $1200 plus $100 shipping. In current $$$, that is almost $2,500, so one could consider the LFT-VIII bass modules a bonus. 

There was another set of those bass modules listed and sold in the last few weeks. Sorry, don't have a link for that listing.

Greg in Mississippi
Shipping on them is $800 which is also very reasonable.  Someone is going to be very happy!  
What does Maggie get for a set of ribbon tweeters ?
$900 a pair.  I believe there are 3 lengths.