Eminent Technology LFT8B’s reversing woofer polarity


I have a pair of the Eminent Technology LFT8B’s and read Dr. Robert E Greene review in the Absolute Sound magazine (2014 I believe) of the speakers where in the review he reversed the polarity of the woofers and said it made a significant improvement. He was going to give the speakers a mediocre review (his words) before doing this and after reversing the woofer polarity he then said they were significantly better and proceeded to give them a rave review. Have any LFT8B owners out there ever tried this? Thank you.

I suspect there may have been something wrong with the review pair for that to be effective. 

I reviewed the LFT-8A/B for Dagogo.com  and owned it, even did the "stacked" pairs for a while which was fun.

NO way that speaker gets mediocre rating for its design, build, sound and cost. I think there was something terribly wrong in previous review ( didn't read it, don't care to) to arrive at such a conclusion.   YMMV

To turn the LFT-8b in an absolute giant-killer (actually, even in stock form it is), use a pair of GR Research/Rythmik OB/Dipole Subs in place of the LFT’s 8" woofers. Unlike "normal" subs, the OB/Dipole will play up to the 8b’s x/o frequency of 180Hz.

Until you do that, there is a remedy for the resonance in the 8" woofers output (in the 1k-1.5kHz range, way above it's x/o frequency), heard as a low-level "whistle". "Davey" has posted on The Planar Speaker Asylum a simple, cheap low-pass filter that suppresses that resonance to the point of inaudibility. It is just a single cap and resister, placed across the woofer's terminals (on the back of the woofer, not the speaker terminals).

I am a newbie to the LFT-8b's having installed them for a little over a month. Robert Greene's review was fresh on my mind when I reversed polarity on the woofers. Expecting some kind of transformation, I heard none! I did it twice, once a week in, and then a few days ago with about 200-250 hrs on the speakers. ( Yes, I've been listening non-stop! )

To be honest, I really wasn't expecting anything major. The speakers wired in their correct polarity was, for me, extremely engaging. I spent most of my time on speaker placement which proved most enlightening. 

BTW @bdp24 turned me onto the ET's. I put the same question to him on another post. And It was Doug's review that moved things forward, having  no dealers nearby. 
Hi bdp24

I appreciate your input and suggestions. 

I went to GR Research's website and I don't see the Rythmik/OB dipole subs you're recommending. Does GR Research still sell these or have they been discontinued? Do you use one or two and where do you set the crossover point at. 

I don't hear that "low level whistle" from the woofer you mentioned. Just because I don't hear it doesn't mean it's not there and everything won't sound better if eliminated. Do you think it's on every LFT8B ot just on some? 

Thanks for your help.


Scot, here’s the deal with GR Research, Rythmik, and the OB/Dipole Sub. GR Research is a 1-man company (Danny Richie) specializing in two things: 1- open baffle speakers; 2- kits for DIY speaker builders. Danny is also well known for his crossover expertise. Rythmik is also a 1-man company (Brian Ding), known for it’s patented Direct Servo Feedback subwoofer design and the sealed and ported subs incorporating the servo design.

Danny was already offering a sealed sub when he learned of Brian’s then new servo system, and thought combining an open baffle woofer with the servo system would make a killer sub. Danny contacted Brian (they are both located in Texas), the two put their heads together, and the result is the OB/Dipole Sub.

Both men and companies sell the sub, in kit form only. Rythmik lists the sub on their website in the "Custom Installation" section. The listing shows the A370 plate amp and 12" woofer that comprise the kit, not installed in the requisite OB frame into which the kit is installed (the consumer is responsible for the latter---see below).

GR Research lists the sub on it’s website in the "DIY Subwoofer Kits" section. In that section, all the various versions of the OB/Dipole Sub (1- economy plate amp and one woofer; 2- that plate amp and two woofers; 3- the more advanced A370 plate amp and one woofer; 4- the A370 plate amp and two woofers; and 5- the A370 and three woofers) are pictured, again as on the Rythmik site just the plate amp and woofers, no OB frame.

In each of the OB sub listings on the GRR site, links to diagrams for both W- and H-style OB frames are provided (just click on the highlighted link), as well as a link to a woodworker in Canada who is making fantastic H-frames (for one, two, and three woofers) in flat-pack form. The frames are CNC cut out of 1" (baffle) and 1.5" (top/bottom/sides) thick MDF, with dadoes and alignment dowel pins to make assembly very easy (only wood glue and clamps required).

For lots of info, pictures, and discussion of the OB/Dipole Sub, head over to the GR Research section on the Audiocircle Forum.

Hey bdp24

Thanks for the explanation, I’m sure I would have eventually figured all that out, only problem is I would have been 5 years older! Does Rythmik sell this sub already built? I would like to hear one. The other sub System I would like to hear is the “Swarm”. Thanks again, very interesting. Take care

No Scot, both Rythmik and GR Research sell the OB Sub as a kit only. But the Canadian woodworker offers his H-frame fully assembled (and finished if you want) in addition to shipping it as a flat pack. To see what it looks like, look up the Virtual System of Audiogon member kennythekey (using just "kenny" as your search word). Kenny had his frames built and veneered by the Canadian.
Not to hijack this thread, but many thanks to bdp24 for all your past posts about the LFT-8Bs -- I ended up purchasing a new pair a couple years ago from someone who purchased them but never ended up using them due to life changes (lucky find).  Funny side story -- the dealer he purchased them from mixed up the boxes for the matched pair of panels and woofers (they come in separate boxes).  I ended up with a new, but unmatched pair, and when trying to assemble them, the predrilled holes were too far off to make the connection, but too close to be able to make a clean new pilot hole!  The woodworkers and DIY guys will know what I'm talking about... SOOOO, before I could even hear these I had to spend some analyzing the issue, which led to some careful application of plastic wood and re-drilling... thank goodness I came into with with a woodworker background, so I was able to correct the issue cleanly -- lol, do we all go through this stuff, or am I somehow in debt to the karma police?

Anyways, what an incredible set of speakers.  When I was researching, I was on the fence between these and open baffle designs -- mainly the current offerings from Spatial.  I still would like to compare these to some Spatial Sapphire M3's someday, and would be highly interested in reading the opinions of anyone who has any about this, or even better has perhaps heard both designs.  

To my ears, and this is coming from a fairly long and varied experience with other very nice speakers, these are nearly perfect for my tastes.  The imaging is one of the things that people sometimes mention is just sort of mediocre, but in my case I'm finding it to be totally holographic and pinpoint accurate, while also being large and immersive... shrug.  They are *very* sensitive to placement -- micro adjustments in any way can bring a notable change.  Finicky position tweaks and experimentation has been a large part of my history with these, but I don't find this to be a fault in any way of the speaker... I look at it as the added care needed for adjusting and maintaining a precision instrument -- it needs more finesse and care than a generalists tool, but once set up properly, it excels.  A high level racing bicycle requires more careful alignment of all parts versus an el cheapo mountain bike, for example.

My one complaint, in my system, has been in regards to the treble.  Sometimes it's just a bit forward and hot for my ears, and I find it can be a little bit fatiguing.  However, I'm admittedly prone to being sensitive to this.  The effect varies widely from recording to recording, and I don't have other 'spare' high end gear on hand to mix-and-match to run a process of elimination.  I'm left wondering if it could be how they play with my upstream components, or some untamed room brightness exacerbated by the nature of the dipoles, or just the nature of the speakers.  It could also just be the mastering of the recordings themselves.  Maybe these are SO honest and revealing, that any harshness in a recording can easily grate on the ears.  It's usually in the mid to upper treble region, where saxophones, female vocals, electric guitars, and treble-leaning synths commonly venture.  I do only have a few diffusion panels in an otherwise fairly bare drywalled room -- maybe the answer is to add some carefully placed absorption panels.  Even though the speakers are almost 5 feet off my front wall and a few feet from the side walls, I could still be getting too much bounce.  It would help be to know if anyone else who knows or owns the LFT-8Bs has experienced this same 'peaky treble' - ?

Otherwise, I'm happy as a clam in audio nirvana... (are clams happy?)...

My tech disconnected the tweeters and placed the speakers with the tweeters facing the outside - they sound and image much better. 
His own speakers may have had their phases reversed. Subwoofers can be tricky. If you are crossing down low without a full two way crossover and your main speaker's bass is on the fat side it may well sound better with the phase reversed. Back in the day with dipoles there was a strong movement towards wiring subwoofers out of phase. If you are crossing under 80 Hz with a full two way crossover running a steep slope you will have to go back and forth a few times to pick up on the difference. Crossing up at 100 Hz the difference is very noticeable. 

One thing to remember about dipole planars is that the rear wave reaches the front wall (behind the speakers), is reflected off that wall at the same angle but in the opposite direction, eventually reaching the listeners ears delayed in time in relation to the same sound coming from the front of the speaker. The front and rear waves may reach the listener’s ears in perfect phase, 180 degrees opposite each other, or anywhere in between. That creates the possibility (probability, actually) of comb filtering. And that’s just with the planar section of the ET LFT-8b (and all other hybrid designs).

The x/o in the LFT-8b is symmetrical 1st order, so the bottom of the Linear Field Transducer’s (hence it’s model nomenclature) passband and the top of the sealed dynamic woofer’s have a broad area of overlap, centered at 180Hz. You want the output of the two drivers to sum rather than cancel, which brings into play the relationship between the front and rear waves of the LFT drivers, as discussed above.

One cool benefit of using the GR Research/Rythmik OB/Dipole Sub in place of the stock ET woofer is that the Rythmik plate amp (included in the Sub kit) has a phase/delay control that provides continuously-variable phase rotation/delay, from 0 to 16ms/180 degrees rotation. This allows one to position the LFT-8b and the OB/Dipole Sub side-by-side for maximum coherence and imaging, while simultaneously allowing optimum phase alignment regardless of speaker/sub distance from the front wall. Another benefit is with both speaker and sub being dipole, their relative outputs remain constant regardless of their distance from the listening position (the output of dipole and direct radiators fall off at different rates as listening/measuring distance changes).
Regarding any perceived brightness in the LFT-8b, the midrange/tweeter x/o (again, symmetrical 1st order filters) is located at 10kHz, well above the brightness range. The LFT-8b allows for three tweeter output settings, but that won't help with brightness. What will help is a superior tube amp (a Music Reference RM-9 MK.2 or RM-200 Mk.2 will work nicely), one reason being the LFT drivers, unlike other magnetic-planars (I'm looking at you, Magnepan) are an easy 11 ohm load, almost purely resistive. The LFT-8b is very insensitive (low-to-mid 80's), but not so much with the woofer run separately. Another factor is toe-in; try the LFT facing straight ahead, or with just a little toe-in. I use diffusion behind mine (Vicoustic 3D), but I have a warm room. For colder rooms, try absorption on that wall (or the side walls) instead.

For those who missed it: the LFT-8b reproduces 180Hz to 10kHz from a pair of LFT drivers, one above the other. Now THAT'S a wide bandwidth driver! Superb coherence and timbral uniformity. As the pianist's hands move up and down the keyboard, every note has the same timbre as every other. My Infinity RS-1b failed THAT test (and the GRR/Rythmik Servo-Feedback Sub is a considerable improvement over that of the RS-1b).
As long as I'm here ;-) :

I'm assuming every LFT-8b owner bought and is using the Sound Anchors stands specific for the speaker. If so, and you intend to keep the ET's for a while, an accessory to consider is the Seismic Pod by Townshend Audio.

While many speakers are candidates for the full Seismic Platform or Podium (I forget which is for loudspeakers), the LFT-8 mounted on the dedicated SA stand is not one of them. The SA stand is a T-shaped outrigger design, and Seismic Pods installed in place of the stock spikes works great. The LFT's center of mass is such that a "C" Pod bolted onto each of the two front legs and a single "D" Pod on the lone rear leg balances perfectly. I had John at Townshend send me Pods made with a bolt hole through the top "cap", which allowed me to bolt the Pods directly onto the bottom surface of three legs (using thread adapters I got from those provided with the IsoAcoustic GAIA footers ;-). The top of the cap is the same diameter as the width of the SA legs, so the pairing looks they were made for each other. Whether the sonic improvement justifies the expenditure I'll leave up to others. I'm not going back to the spikes ;-) . 
Likewise, all info is much appreciated, good sir -- really key insight shared here.  Also, fun to find a gathering of fellow LFT-ists :).  I'm off to experiment with positioning again, with less toe in this time, as per your suggestion.  Bruce mentions in the manual that they generally sound flat when on-axis with the listener, so I've been doing that by default, but perhaps this is very room and personal taste dependent.

In  the past 1 1/2 year three tube amps and three pre-amp / phono stage has passed through the ET’s. I  believe with @bdp24 that tubes in the signal chain mitigate brightness. I started with an all tube combo, vintage MFA Luminescence pre + 100 w push pull triode. Needless to say there was no brightness. However, the Luminescence was giving other problems. The preamp chain then  went solid state with Lightspeed Passive Attenuator and a current mode phono stage, creating a more revealing and transparent sound. No brightness, again. I played with a vintage International Projector Corp am 1026 amp for two months. With only 22 w I have come to realize all the talk about how difficult the ET’s are to drive, minimum 100w..etc. is BS. Right now my main amp is from Japan,  Mactone mh-300 b, with output again in the 20’s. Four 300b’s in push pull class A configuration are playing very well with the ET’s. No brightness to report.

Room Placement

My room is 3.3 x 9 M. The ET’s sit 2.8 m from back wall, almost 1/3 into the room, with 40 cm from side wall and quite a bit of toe in.
I am getting the holographic, image specific, and wide soundstage that I was told only box speakers excel in. I didn’t expect it from the ET’s, but thoroughly enjoyable.


Through a recent change in cartridge I did get a glimpse of ET’s brightness with the Audio Tekne MC 6310. Framer described it as more Lyra- like, i.e. analytical, than Koetsu. Well that is a pretty apt. However, adding a damping pad from Origin Live helped greatly.

@ bdp24 Thanks for the Townsend pod information. My only question is whether removing The the sound anchor stand and simply placing the speaker directly on a Townshend speaker base might not be a even better solution?

Interesting question, @ledoux1238. If I didn't already have the Sound Anchor stands and like them as much as I do, the Townshend Podium option would be worth considering. I'm sure the lead shot-filled Sound Anchors stands are at least as non-resonant as is the plate of the Podium, and of far higher mass. My thinking is that the higher mass may provide a more stable platform for the high vertical center-of-mass of the ET panels. Another thought is that the SA stand bolts directly onto the bass bin of the LFT-8, with the Townshend Podium the latter just sits on the plate. Either choice will do nicely!
Leaving the SA stands is probably the way to go with a bit more mass, as you say, at the bottom. How is the height of the Townshend pods affecting listening on the vertical axis? Do you need to change your chair / sofa height?  I find the ET’s particularly sensitive on the vertical axis. I sit low on a reclining chair while listening. And I find that tilting the ET’s 1.5 cm forward gives me the best soundstage and imaging. Adding the pods will raise the speakers quite a bit. 
Placement and the amplifier driving the 8 and 16 model ET speakers is key.  I've heard both speakers about ten times with some great amplifiers at a local dealer who's sold them longer than any other shop in the USA  ETs can sound incredible, deep bass, midrange, detail and smooth in the right setup. Can be really fun speakers to listen to.  
@ledoux1238: The Townshend Pods raise the height of the LFT-8 about 1.5" above that of the SA stands’ stock spikes. One reason I prefer planars is because of the higher image they create relative to most "box" speakers. I like looking up at the "stage", not down on it (as if from the balcony in a theater).

I sit in a low-back stuffed chair, my ears around 38" off the floor. The panel of the LFT-8 contains a pair of vertically-aligned---one above the other---m-p drivers, almost filling the entire 12" X 48" panel. The single ribbon tweeter which runs alongside those drivers is centered above the middle of the panel and the midrange/bass drivers, and is of course very limited in vertical dispersion. If your ears are below the tweeters radiation pattern, the rear of each speaker can be raised above that of the front, to aim the tweeters output a little downward. A couple of MDF or Baltic Birch blocks will do for testing, a set of BDR discs used permanently if you like (their 2-3/4" diameter is perfect for supporting the bottom of each pod. I use them between the Pods and my carpeted floor).
Thanks for the BDR tip. I am sure I can source locally for something similar. The Townshend pods will be inserted sometime down the line.

There is a question about adding OB subs to the ET’s. I think you run GR Research servo subs and you do not connect to the ET’s woofers. You mentioned somewhere that the ET’s crossovers still engage the woofers even if they are bypassed. Have you tried to disengage the woofers from the crossover?

@ledoux1238, the LFT-8b contains two pair of binding posts, one for the panels, one for the bass bins. The speaker comes with a set of jumper wires between the two, to facilitate running the speaker with a single stereo amplifier (the power amp can be connected to either set, to the panel posts makes the most sense). If one wishes to bi-wire or bi-amp, that jumper may be removed. That also allows one to not connect the bass bin at all, which is what you do if using a separate woofer/sub. So the woofer doesn’t see the signal at all, but the power amp still sees all frequencies, including low frequency ones.

One of the benefits of full-on bi-amping is keeping bass frequencies (in the case of the LFT-8b, those at and below around 180Hz) out of the power amplifier, which raises the power available to the panels whilst simultaneously lowering the distortion the amplifier produces (especially advantageous with a tube amp). The LFT-8b instruction literature includes details on how to create passive 1st-order low-pass and high-pass filters (an external x/o for bi-amping), the employment of which provides those full bi-amping benefits.

If the LFT-8b is used without a separate external x/o, while the power amp will see bass frequencies, the m/t panel won't, as the speaker-level x/o is already removing low frequencies from the signal sent to the m/t drivers. It's not as complicated as a first reading of all these details may make it seem!

1. Can I simplify use two separate amps, one connected to m/t panels and one connected to the woofers, without a cross-over? Do I need some form of volume control for output mismatch?

2. From reading the manual, I need two x/o in passive application, one 180hz high pass and one 180hz low pass. 
a. Where can one find ready made high and low pass x/o modules?
b. Where to I connect these to?
c. Would I need additional volume dial to match output?


1: You sure can. However, if the two amps don’t provide the same gain (fairly likely), you WILL need a means of adjusting the volume of the higher gain one. Some power amps include a volume control, but these days that’s rare. A simple outboard volume "pot" at the input of the power amp will work, but will of course necessitate an extra inter-connect.

By the way, if you use two identical amps, you can bi-amp either horizontally (one stereo amp for the panels, one for the woofers) or vertically (one stereo amp for each complete loudspeaker).

2: Exactly correct.

a: This subject has been discussed in detail many times before on Audiogon, so do a subject search; there are lots of products to choose from. I have the nice little x/o Nelson Pass offered in the First Watt B4, but it is no longer offered factory-assembled (kit only now), though it is more x/o than you need for this application (plus it retailed for $1500, perhaps more than you want to spend). There are LOTS of self-contained volume pots (even from ebay vendors), one from HSU (the maker of subs) for under $100. Cheap volume pots are notorious for channel imbalance, so get a good one! When he was alive, Roger Modjeski was offering a "Volume Pot In A Box" pre-amp (he was a proponent of passive pre-amping). Contact Music Reference to see if there are any left in stock.

However, the best way to do the filtering (possible because that needed is the simplest of all types) is a passive, 1st-order (6dB/octave). All that requires is one cap and one resistor per channel, which can easily be soldered onto the input jacks on the power amps, inside the amps. Why is that ’best"? No extra inter-connect required, no extra breaks in the signal path. Less is more! (that goes for you too, musicians ;-)

If you have a good tech in your area, having him do the work won’t cost you much. I had Tom Carione at Brooks Berdan Ltd. in SoCal install the exact filter you need in my Bedini 25/25. I had him replace the stock binding posts with Cardas at the same time.

b: already answered.

c: ditto.

I hope this doesn’t sound too daunting. Used as delivered from the factory, the LFT-8b already sounds great (have you read the review by Robert Greene in TAS, or the reviews in UK mags?) . I would listen to the speaker stock, see if you like it enough to take it to another level. Be sure to get the dedicated stand Sound Anchor makes for the LFT-8b. If you’re familiar with that stands they make for the Vandersteen speakers, you’ll know what they look like. Eminent Technology stocks and sells them.

@bdp24  I greatly appreciate your answers. As it turns out one of the amplifiers that I will be using, Mactone mh 300b,  has a built in volume control.  It put out 22 watts and I am using it right now to drive the LFT-8b's to satisfactory level. But I intend to use it to drive the M / T panels in the bi-amp set up. There will be a 100 w tube mono's returning from repairs. These will drive the woofer. I will start with no x/o and use the volume control of the Mactone to match levels for now. 

I also got in touch with Bruce T. and he recommended I look into x/o's from Marchand Electronic which I believe you have commented on in previous post. 
@ledoux1238: Yeah, the Marchand x/o’s are very well respected. They make filter "cards" for every conceivable need, the 1st-order you need being the most simple.

As for using the volume control of the Mactone to balance the panels and woofers, remember this: a volume control doesn’t provide gain, it only attenuates the signal sent it (with the volume control set fully clockwise, it is proving zero attenuation). For your plan to work, the Mactone will need to have greater gain than do the woofer amps. If the woofer amps have higher gain than does the Mactone, the volume control on the latter will not be able to bring that amp up to the level of the former. Even wide open, the gain of the Mactone will remain less that that of the woofer amps. On the other hand, if the Mactone has greater gain, that amp’s volume control will allow you to attenuate (lower) its output, thereby providing a means of balancing the panels and woofers. See what I mean?
@bdp24 Regarding the potential mismatch of the two amps, your point is crystal clear. I will know in two weeks time.

If there is a mismatch, the issue of which x/o remains. The initial thought was a passive x/o, 1st order. However, several comments, including yours, I believe, indicated that the particular passive x/o from Marchand was not as good as their active tube. You have pointed to the less than stellar parts quality in the passive. There is also a clear price difference between the two units.

I suppose going active will provide the most flexibility for future subwoofer upgrade, or, heaven forbid, a change from the ET’s to other transducers.

Regarding your earlier post on the TAS reviews of the ET’s, I think I’ve read all the available professional reviews and most of the forum posts on the LFT 8b’s before I contacted Bruce T. I have had the pair for over a year.  In terms of placement / interaction with my listening room, I believe they are optimized. I would like very much to push to optimize the speakers in other ways, hence the bi amp queries. And eventually, I ‘d like to upgrade the the internal x/o caps, and try OB subs. 

My list of active crossovers includes:

Marchand XM-44
Beveridge RM-3
Accuphase F-25

With each of these I have the flexibility for different slopes and frequencies. I can also attenuate (Beveridge, Accuphase, Marchand) or add gain (Marchand). I've used these frequency dividers with various panel speakers and I'll never go back to passive crossovers again. Unfortunately the LFT 8b's crossover is too high for my taste, I prefer to keep it under 100 Hz (and currently use 80 Hz). Not sure why Thigpen chose the higher crossover frequency, but I'm sure he had a reason.
@clio09, I believe the reason for the 180Hz x/o from the panel to the woofer is because the dual midrange LFT drivers don't produce enough output below 180Hz to do otherwise.

But remember, the LFT-8b wooder is just that: a woofer, not a sub. Looked at it that way, the 180Hz x/o in the speaker is unusually low. The LFT-8b is a 3-way design, and most 3-ways x/o from their midrange driver(s) to their woofer(s) at a frequency far higher than 180Hz.

On reason the GR Research/Rythmik OB Sub works so well with the LFT-8b is because the sub can be used up to a x/o frequency of 300Hz (the reasons why can be found on the GR Research and Rthmik websites). Used with the LFT-8b, the OB serves as both woofer AND sub.
@bdp24 Yes I realize the LFT-8b has just a woofer, and not an active sub. My bass array are just woofers too, based on the woofers Roger Modjeski used in his ESL system. His theory was to keep the crossover point low from the panel to the woofer, so his ESL panel (a two-way) was designed to go down to 100 Hz. He listened to a lot of Leon Redbone and some other male vocalists whose voices went low enough that at a higher crossover point than 100 Hz you could start hearing the vocals in the woofers.
I did not know the LFT-8b were three way. What's the other crossover point?
@clio09 You have convinced me that active x/o is the way to go. And also, more research is needed before I jump in.

@bdp24 The GR Research / Rythmik OB subs come with its own plate amps. Do you then use one set of amps for the M / T panels only?  You mentioned that the woofers on the ET’s are bypassed. In terms of connections, are there one line out each from the preamp to the m/t amp and the GR plate amp? 

I sincerely apologize for my questions which, I assume, is rudimentary for you guys. Just trying to learn from the masters! 
@clio09: The LFT-8b panel houses a pair of LFT midrange drivers, and a single ribbon tweeter. The x/o point between the two is at 10kHz, symmetical 1st order. The speaker is fitted with two sets of binding posts, one for the panel and one for the woofer.

Bruce Thigpen’s earlier LFT loudspeakers---the LFT-3, -4, and -6---ran the LFT drivers all the way down into the woofer territory, with no dynamic woofer. But those models had a bigger array of the LFT drivers. The use of a dynamic woofer in the LFt-8b is a compromise, one that could enable BT to offer a full-range model with bass extension and retail for $2499. He put a lot of effort into achieving a seamless blend between the woofer and LFT drivers. The LFT-8b does NOT suffer from the discontinuities other hybrids do.

@ledoux1238: When adding the OB sub to the LFT-8b, yes, you need only one stereo amp (or a pair of monos), and it drives the panels. With this set up, the LFT-8b woofer is not used at all, and you just remove the jumper cable that runs between the two sets of binding posts, hooking up your speaker cables only to the posts for the panel.

But remember, this is possible only with the GR Research/Rythmik OB sub, as it plays up to 300Hz. The LFT-8b’s crosses over from the woofer to the panel at 180Hz, far above what "normal" subs can play up to.

As for the connections required to run both the LFT-8b and the OB sub, you need either: 1- two sets of output jacks on your pre-amp---one for the sub plate amp, one for the amp powering the panels; or 2- a "Y" jack or cable, to run a set of cables to both the subs plate and the power amp for the panels. If you use an active electronic x/o that provides both high-pass and low-pass filtering, you need only one set of pre-amp outputs. The x/o will have two pair of output jacks, one for each filtered signal. In that case, three sets of interconnects will be required: one set for pre-amp to x/o, and one for each of the two filtered signals---the speaker power amp and the sub plate amp.

@bdp24 Acquiring an active x/o seems the versatile path with bi-amp or sub-woofer application. With an active x/o in the signal path, the advantage seems to be adjustability, a way to dial-in the most ‘appropriate’ sound. Would you say that an active x/o allows the speaker system to perform at a higher level? With the LFT8b’s, you get smoother highs, wider soundstage....etc? What is the most significant improvement in a bi-amp, non sub -woofer application?

@ledoux1238: Here’s what I would do:

Get yourself a pair of LFT-8b’s and live with them for a few months. If you then feel you want to get more out of them, address the reason for your dissatisfaction. Why worry about bi-amping when you haven’t yet heard the loudspeaker?

For the money it would take to add a good crossover and second amp, you could instead add a subwoofer or two. A "normal" sub, not the OB. In my opinion bi-amping will not provide as much improvement as will adding a sub or two.

The LFT’s weakness is the woofer: it limits the maximum SPL the loudspeaker can produce. Bi-amping will NOT change that, adding subs will. If you don’t want to go with the OB, regular subs are a good second best. Rythmik and GR Research both offer the F12: Rythmik with an aluminum cone woofer (F12), GRR a paper cone (F12G). If you desire more output, there is the F15HP by Rythmik. Or any good sub of your choice.

Even when bi-amping the LFT-8b, the stock x/o stays in place. Thigpen uses x/o parts that allow him to offer the speaker for $2499/pr. A real good way to upgrade the speaker’s sound is to build a duplicate x/o (using the stock parts values), but with premium parts. The x/o schematic is viewable on the ET website (and is included in the owner’s manual), and if you aren’t into soldering, a good tech can build it for you.

The OB Sub provides the improvements of both bi-amping and adding subs, as well as creating a full-range OB loudspeaker. That would be my first choice. But it's not for everyone, perhaps not you, ay?
Hi everyone

I just wanted to share something with everyone who owns LFT8B’s.

About 6 months ago I emailed Grant Vandermye (myesound.com) best known for making stands for Magnepan speakers among several others. I had his stands on my 3.7i’s and really liked them. I asked Grant if he made those same stands for the LFT8b’s and he said he did not. I asked him, would he consider making me a pair for the LFT8B’s and to my surprise he said sure, why not. He’s a really nice guy and a pleasure to work with. Long story short....

Six months later, with the help of friend we set them up yesterday and all I can say is WOW! I cannot believe the improvement. Anyone who owns these amazing speakers needs to hear these stands. The first thing that just hits you is how much more stable the instruments are within the soundstage. I could not believe the improvement. I am hearing background details on familiar albums that are mind boggling. Bass is much tighter and much cleaner. Midrange and the high frequencies are much more open. They are, in my opinion, a must hear. For the money ($560.00 usd pair incl shipping) it is a tremendous upgrade for not a lot of money. Enjoy!


Cool Scot, I’m emailing Grant to get a pic of the LFT-8b stand.

Is everyone watching Steve Guttenberg’s Audiophiliac Daily Show blog on YouTube? The latest has Steve and Herb Reichert discussing 300B tube amps and horn loudspeakers. But there were also two things said which are directly related to the LFT-8b.

1- Eminent Technology specs the LFT-8b as having a sensitivity rating of 83dB. That, according to one Audiogoner, rules it out as a loudspeaker worthy of consideration. In the Steve & Herb video, both emphatically state that sensitivity is a highly over-rated factor in loudspeaker design, and that what you really want is as high an impedance as possible. That is of course especially true with a tube amp, for the obvious reason.

The LFT-8b has a nominal impedance of 8 ohms (the Maggies---also a magnetic-planar design---are nominally 4 ohms, but dip to just below 3 at some frequencies). However, the LFT midrange and tweeter drivers, when separated from the dynamic woofer, present a constant 11 ohm load to the amp. A very good reason to bi-amp the LFT-8b.

2- Herb recounts a story of listening to the Altec A-7 and Wilson WATT/Puppy side-by-side in the late-80’s. He and his assembled guest listened first to the Wilsons, quite liking the sound. But when the Altecs were played, Herb says the "life-size" image they produced made the Wilson image appear as a miniaturized version of the same picture.

I have stated many times that I prefer planar loudspeakers over boxed ones for that exact reason (likening box speaker sound to a doll house), amongst others. When I hear a voice hovering about 3’ off the floor, my suspension-of-disbelief evaporates. The LFT-8b produces life-size images, and singer’s voices at life-like height.
Hi all

Regarding the amp requirements to properly drive the LFT8B’s, too many people worry about having enough watts per channel. My experience has taught me that the quality of the amp is much more important than the watts per channel.

I had a Cambridge stereo amp on them (200 wpc) and it was good. Not knocking Cambridge, they make a nice amp, but when I switched to the Pass Labs XA30.8 and heard it for the first time, I laughed out loud. That amp, on paper, is rated at only 30 watts per channel (solid state) but it’s all power supply. The thing weighs 84 lbs, it’s rated at 30 wpc @ 8 ohms, 60 wpc @ 4 ohms & 120 wpc @  2 ohms and it still has 12 dB of headroom! It’s a class a design. That amp drives those LFT8B’s effortlessly and always sounds incredibly musical. Watts per channel means nothing. 


Thanks for mentioning the Audiophiliac show on YouTube, I’ll definitely check it out. 

Regarding the Mye stands for the LFT8B’s, I’ll bet he doesn’t have any pictures on his website yet, mine were the 1st pair he’s built. If you look at the pictures of the stands for the Magnepan 3.7’s you’ll get the idea, it’s basically the same stand. I’ll try to get a picture posted on this website (if Agon will allow it).

I also forgot to mention the most important attribute of the stands, the upright braces that attach from the back of the stand to the sides of the 60” panel. The upright braces prevent the panel from moving forward or backwards when the music is playing. HUGE IMPROVEMENT. To test the stability of the panel, I put my finger on top of the panel and tried moving it forwards and backwards, it felt like it was anchored to the floor, no movement whatsoever. The biggest benefit is image stability. The instruments within the soundstage are now precisely placed and pinpoint and rock solid. The improvement is off the charts. Background details are much better. Background voices are more intelligible. On familiar recordings you hear things you never knew were there. Everything is much more open. Like I said in my original posting, a must hear for anyone who owns these speakers. No negative, all positive.

I also prefer a Planar magnetic driver to any dynamic driver. It’s a simple matter of physics. The heavier dynamic driver will never start and stop as quickly as the planar drivers. I’ve owned Magico’s, Avalon’s, and the list goes on, some of them costing more than 10x the price of the LFT8B’s. I obviously prefer the LFT8 B’s. The fact that they only cost $2500.00 pair is a gift. Thank you Bruce Thigpen! Take care.


very important information that  you are sharing. The flexing of the panels adversely affect sound quality. I believe retrofitting  vertical bracing to the sound anchor stands that I am using would be another solution. 
There is a guy on the Planar Speaker Asylum who has run a brace between his pair of Magneplanar Tympani T-IVa and the wall behind them. He says that has resulted in a noticeable increase in not only sound quality, but also increased bass out of the twin woofer panels. Grant offers a stand for the T-IV, but it costs as much as I paid for my pair of that loudspeaker!

@scothurwitz: There is no pic of the LFT-8b stand on the Mye Sound website, nor is it listed on the pricing page. I emailed Grant to see if he took a pic of the pair he made for you. May I contact you via email, and bother you for a pic or two? Thanks---Eric.

I remain astonished at the fact that many more people own Magnepan 1.7's than the LFT-8b. Eminent Technology is a very low-profile company, as are a number of my other favorite hi-fi brands (Music Reference, EAR Yoshino, Townshend, London, GR Research, Rythmik). Buying the LFT-8b requires a leap of faith for people without an ET dealer nearby. I luckily had one such: Brooks Berdan Ltd. in Monrovia, CA. Brooks chose the LFT-8b as his magnetic-planar loudspeaker, and steered me towards it (and towards Music Reference). Thanks Brooks, miss ya buddy :-( . 
While I am sure the Mye stands are excellent, there is another person who also makes stands for Maggies. The company is Magnarisers and while I do not own Maggies I was impressed enough with the stands and their price that I contacted him to make stands for my Acoustat Model 2 speakers (sans interface as I use the direct drive amps). He did a great job for a reasonable price and there was a noticeable improvement getting them off the floor.
@clio09: Yeah, the Magnariser's are a great value. Their Maggie stands are a simplified and lighter weight version of the stand Sound Anchors has for years been making. The difference between the Sound Anchors and Magnariser Maggie stands and the Mye is obviously the Mye providing bracing 2/3rds the way up the panel height, in effect stiffening the rather flimsy MDF frame the Maggie drivers are mounted in.

In contrast, the Eminent Technology LFT drivers have a stiff metal frame onto which they are bolted. That frame is then mounted into a cut out in the speaker's MDF baffle. Supporting and stiffening that MDF baffle can be only a good thing! 
Hi guys (and gals)

I to, probably like most of us, used the Sound Anchor stands and liked them. You fill them with sand, adjust the rake angle, and you’re good to go.

One of the weak points of the LFT8B’s design is in the way the panel attaches to the woofer box (no offense Bruce). Five small wood screws screwed into an MDF woofer box just isn’t very secure. If you put your finger on the top of the panel and move it forwards & backwards there is a lot of movement. With the Mye stand in place, no movement whatsoever. That panel now feels like it’s part of the floor!

The thicker metal Mye stand with the upright braces that bolt to the thicker metal bases of the stand allow the upright braces to attach to the sides of the panels with a metal “C” clamp and  makes that panel MUCH more stable. The “C” clamp attached to the sides of the panels was done at my request. Grant wanted the upright bracing to screw into the backs of the frames but I felt the attachment points were too close to the tensioning adjustments for the midrange panels and didn’t want to risk going anywhere near those cam adjusters. I felt the “C” clamps attached to the sides of the panels were an acceptable aesthetic compromise. That is the key element of the Mye stand and why the imaging within the soundstage becomes rock solid and instruments are now pinpoint stable. 

My my pair of Mye stands were the first pair Grant has ever made. It doesn’t surprise me that there are no pictures of them on his website yet or have been added to the price sheet. I feel pricing is very reasonable. I paid $560.00 for the pair including shipping (from Canada) to Illinois. He includes all necessary hardware and an Allen key for assembly. The fit and finish is very nice (all metal surfaces are powder coated). The price/performance ratio is well worth it. 

This is embarrassing to admit but here we go, I am terrible with computers and have never used the camera on my smart phone (I’ll wait for the laughter to die down) I will try to figure out how to take a couple of pictures and email them to my computer so I can post some pictures for everyone. 

Anyone who would like to contact me through email is more than welcome to. I don’t think Audiogon allows people to post their email but if they do here it is:  scothurwitz@comcast.net. If that doesn’t work, feel free to direct message me. Tanks and take care.


Thanks Scot, expect an email from me ;-) . Grant sent me a diagram of the stand in an email, and it looks fantastic. I'm very familiar with his Maggie stands, which also secure to their frames with C clamps. I think I may get my LFT-8 Mye stands made to screw into the baffle, but I'll discuss that with Grant. I'm a little more concerned with aesthetics than I should be ;-) , and those C clamps give the Mye stands a homemade look.

The Mye Maggie stands are far better than the Sound Anchors version, as they brace the thin MDF baffle, the Sound Anchor just bolting onto the bottom of the Maggie baffle. The same is of course true with their LFT-8 stand, but it was quite an improvement over the stock ET "legs", which are a joke, inappropriate on such a fine loudspeaker. 
Hello All

Resurecting this after a few months. Asking all ET LFT-8 owners, are they as fussy as they sound to set up? Do they have a really small sweet spot, or are they a little more forgiving then some make them out to be? Are the older models like the 6 more desireable?