Eminent Technology LFT-III loudspeaker
The Eminent Technology LFT-III also clearly qualifies as a new design by any standard. Like the Apogee Ribbons, it is one of the few new speaker systems since the appearance of the Magneplanars and Quads to introduce a major new departure from cone- or dynamic-speaker technology.
The Eminent Technology LFT-III is a new planar-magnetic doublet design, using a single-diaphragm transducer claimed to give a response ranging from 35Hz to beyond 40kHz. Unlike both the Magnepan planar magnetics and the Apogee bass driver, which are topologically similar to one another, the Eminent's magnets are on both sides of the diaphragm. This results in true push-pull operation, which, Eminent Technology claims, produces substantially more linear operation, keeping the diaphragm within a constant-flux magnetic field over its entire displacement range.
The conductors within the diaphragm, etched as if they were on a circuit board, are flat, with narrow gaps between each trace. The traces are very thin, keeping the impedance at a high 822 ohms. Crossovers segment the diaphragm so that a 2" line source reproduces the full range for good dispersion, and the remainder of the diaphragm plays only low frequencies.
The specifications are outstanding. You may never read all the type we put in the "Specifications" sidebar, but this time you should. Few companies have ever been as thorough in providing such specifications and few have ever made claims as strong, including very flat frequency response, outstanding power handling, astonishingly flat phase response, and exceptional speed.
There is also considerable flexibility in set-up. You will need at least three feet of clearance from the rear- and side-walls to get the best response, but the speaker already has jacks for biwiring, and can be rewired internally for use with an electronic crossover (although I see no reason for such additional devices). The treble-energy level is also variable over a reasonable range, with three settings allowing you to tailor the speaker for a given room and system, although even the most significant treble cut still leaves a lot of apparent upper-midrange and treble energy.
In short, the Eminent Technology LFT-III is an innovative planar speaker with significant design advances. It is also relatively good looking. While hardly small, it is thin, and the mix of oak and a black grill cloth gives it styling that should be acceptable with most decors (footnote 1).
Three Minor Flies in the Magnetic Flux
The Eminent Technology LFT-III does, however, have three design problems that you should know about:
First, it has a highish modulus of impedance for a modern speaker. Coupled with its lowish sensitivity, it will need an amplifier capable of giving at least 100 watts per channel into 16 ohms: many modern high-current amplifiers simply lack the necessary voltage swing.
Amplifier compatibility is hard to predict. An Adcom GFA-555 will drive the LFT-III quite well, but Krell 100 watt mono amps will not. My advice is to plan on using an amplifier spec'ed at around 200 watts per channel into 8 ohms, or check with your amplifier manufacturer. Eminent Technology is considering a 4-ohm versionsomething I would emphatically endorse.
Second, the speaker is top-heavy unless you use the spikes in the feet and adjust them so they reach firmly into the floor. Even then, it is not kid-proof without a few bricks on the back of the feet, and can present problems on padded carpets. Shadows of the Infinity RS-1B!
Third, it unpacks like a dream and is quick to assemble, but does require some minor tweaking to tighten the diaphragm and ensure proper bass. Instructions come with the speakers: it is an easy five-minute job for both, but you do have to read the instructions thoroughly.
These quibbles set forth, we now come to the sound of the LFT-III: this is one speaker whose sound lives up to the promise of its design technology. Its performance is worth reviewing step by step:
Frequency Response: exceptionally flat, with natural timbre and no apparent coloration. The overall response curve is very flat, and even the adjustments do little to alter the fact that it extends beyond hearing with great smoothness and speed. I could not detect a major frequency coloration on any instrument or type of voice.
While the LFT-III certainly has a different timbre from the Quad ESL-63 or Apogee Duetta II, it is one of the very few speakers to approach them in overall coherence. Further, there are no detectable shifts in speed or transient character and dynamics with frequencyas is the case with the Magnepan IIIA and Infinity RS-1B.
The energy level in the upper midrange and treble may, however, be high for some listeners. The sound has none of the aggressiveness of the smaller MartinLogans, but is much more like a Thiel in overall timbre than an Apogee.
Treble, Bass, and Midrange: It doesn't make much sense to talk about the treble and midrange character of this speaker. When properly set up, it is virtually without individual character in these rangesalthough the overall response is as described above. This often makes it seem to lack characterbut then, a speaker should. It will not romanticize anything, or add euphonic touches. It won't spoil or color anything, either.
The bass, however, is restrained and detailed, rather than warm and full. The speaker is tuned for flat bass to about 30Hz with no hump or extension. There is lots of bass power when there is lots of bass, but there is no subwoofer effect, and the Eminent does not match the Apogees in their apparent ability to reproduce the gut dynamics of the lower bass.
Good bass also requires tightening during set up, careful room placement on the basis of a lot of experimentation, and a good, compatible amplifier. The Eminent Technology LFT-III may sound a bit bass-shylike the Magnepan IIIA or Quad ESL-63if you don't pay attention to set-up.
Transient Speed and Detail: The LFT-III is much closer to a ribbon or electrostatic in apparent speed and transient than it is to the Magnepans or most dynamic speakers. Performance is outstanding.
Dynamics: With the wrong amp, the LFT-III can sound weak and seem to clip. With the right amp, the performance is great. With a good amplifier, the LFT-III plays loud by any standard, and its dynamics are excellent, resolving shifts from low- to high-level passages as well as virtually any speaker around.
Be aware, however, that these dynamics are coupled to a speaker sufficiently lacking in frequency coloration and bass overhang so that you have to keep the volume high enough to approach natural musical sound levels to get the best results. Like other relatively uncolored speakers, there is nothing to warm the bass or lower midrange at lower volumes, and the Fletcher-Munson effect means your hearing's severe lack of sensitivity to low frequencies will then make the speaker seem lacking in bass.
Soundstage: The soundstage is wide and coherent, with excellent placement of instruments and voice without artificial detail or seeming to etch the imaging in place. Depth is very good. The overall sound is just slightly forward, but few are likely to quibble. With careful placement, a pair of LFT-IIIs can sound very natural over a relatively wide listening area.
The Eminent Technology LFT-III is a speaker to be shortlisted by any reader who can afford a top-quality, high-end system. My own tastes tend slightly more toward the Apogee Duettas, but I'd have to say that this is one of the few speakers I'd add to my personal shortlistwhich is currently limited to the Apogee Duetta II, Quad ESL-63, the top-priced Thiels and Vandersteens, and the better Infinities.
The Eminent Technology LFT-III is clearly of reference quality. It has outstanding analytic accuracy and resolution over a wide range of frequencies and a wide dynamic range. Its coherence and integration of all important listening parameters is likely to make it popular both for monitoring recordings and designing electronics and cartridges. Only true bass freaks are likely to miss anything, and they will miss much less than with most speakers approaching this level of coherence.
Footnote 1: Although my design-research group informs me that an all-black and all-beige/off-white version is badly needed to meet WAF (Wife Acceptance Factor) standards.