The category of loudspeaker is perhaps the most diverse niche in the audio world. Electrostatics, ribbons, or quasi-ribbons are all different variations of the box-less design that is commonly referred to as planar speakers. Planar speakers have a distinctive appearance that draws the attention of both the audio enthusiast and the casual observer. Most planar speakers are monolithic in appearance, and tend to dominate the room they are located in. While the visual appearance of these speakers may not appeal to everyone, the unique sonic presentation will capture the attention of anyone who appreciates well-reproduced music. In the late 19080’s there was a large number of manufacturers building this style of speaker. Although several of the prominent manufacturers of this time period have closed their doors, there are still several companies that continue to advance this type of technology.
- Frequency Response: 45Hz – 20kHz ± 4dB, -6dB @50kHz
- Phase Accuracy: ±20° 100Hz-31kHz
- Efficiency: 85 dB/1W(2.83V)/1m
- Dimensions: 9.75”W x 21.5”H x 9.75”
- D Impedance: 8 Ohms
- Crossover: 250Hz, 7.5kHz/3dB
- Woofer Type: 6.5” Paper Cone
- Tweeter Level Settings: 0dB, -3dB, -6dB @ 20kHz
- Weight: 23 lbs. Each
- Available Finishes: Oak, Walnut, Gloss Black
- Warranty: 3 Years Parts
- Retail Price: $950 per Pair
Bruce Thigpen is the man behind Eminent Technology, which is one of the “old guard” audio companies. Bruce developed the ET2 series air bearing tone arm, which has long been considered one of the finest products available in the world of analog playback. In 1987 Bruce was granted his fourth patent, for the Linear Field Transducer. The LFT driver is a push-pull variation of the planar-magnetic speaker design. This design addresses issues that are inherent in the conventional single sided magnet arrangement found in other planar-magnetic drivers. For twenty years now Bruce has been refining the design and application of the Linear Field Transducer. Earlier speaker designs such as the LFT-3 or the LFT-6 used LFT modules only, while later versions have added a conventional bass driver to handle the lower frequencies. The LFT-16 is the entry-level speaker in the Eminent Technology line up, and offers the budget conscious audio enthusiast a way to enjoy the benefits of a planar speaker for a relatively modest outlay of cash.
Eminent Technology LFT-16 review
The Linear Field Transducer panel is a polyester diaphragm with a thin sheet of aluminum foil laminated to it. A voice coil pattern is silk screened onto the aluminum, and an etching solution is used to remove the excess metal. The end result is a precise voice coil assembly that is firmly attached to the polyester diaphragm. This diaphragm is placed in a frame that contains two sets of magnet assemblies located on the front andrear of the driver. This push-pull magnet arrangement maintains far more control over the speaker diaphragm than a single sided design would.1 The LFT driver has significantly quicker response time to the input signal than a conventional driver because of the lightweight of the polyester and aluminum diaphragm assembly. For the most part a planarmagnetic speaker sounds similar to an electrostatic speaker design. Electrostatic speakers have issues with impedance dips, and are difficult for ordinary amplifiers to drive. Since the LFT driver uses a printed voice coil, it presents the amplifier with a non-reactive impedance load.2 Any amplifier that is capable of driving a moderately efficient speaker with an 8-ohm load can be used with the LFT-16 speaker.
The Eminent Technology LFT-16 falls into the large bookshelf category. Speaker dimensions are 21.5 inches tall, and 9.75 inches wide. The 6.5-inch woofer is contained in a small cabinet that is 12 inches tall. The remaining 9.5 inches of baffle height houses the Linear Field Transducer driver and a small ribbon tweeter. Speaker binding posts reside on top of the woofer module. The crossover system is set up for bi wiring, and the user can select from three different output levels for the tweeter. To be honest; the LFT-16 would probably not win any awards based on its aesthetic appeal. It is apparent that “function determines form” rule has been utilized in this design. Aside from the utilitarian appearance of this speaker it is evident that high quality parts are used in every area. While the LFT-16 may be an odd looking speaker, it s unconventional design foreshadows its musical capabilities. The speaker does not look like an average $1,000 speaker, nor does it sound like one.
In order for bookshelf-sized speakers to perform properly they must be placed on high quality stands. A firm foundation must be established in order for the speaker to reach its potential. I placed these speakers on a pair of 24-inch tall Target HS series stands. These stands are made of heavy steel, and all the plates are welded together. The massive center pillars were filled with approximately 50 pounds of sand in each stand. I used blue-tack to couple the speakers to the stand top plate. The LFT-16s were placed seven feet apart, and brought 4 feet out into the room. The LFT driver is somewhat directional, and needs to be angled in towards the listening area. I experimented with the amount of tow-in needed for this speaker, and achieved the best imaging performance when the faceplate is aimed directly at the listening position.
The Eminent Technology LFT-16 is slightly less efficient than the average speaker, and needs to be used with an amplifier capable of producing a fair amount of power. While I enjoy listening to my Electra-Print 300 DRD amps, they are definitely not the right choice for these speakers. Out came the tube amps,3 and in their place I installed a pair of the Monarchy SM 70 PRO amplifiers. The Monarchy amps produced 80-wpc of power, and are a proper match for these speakers. I retained the Electra-Print PVA preamplifier in the system. As usual, the Audio Magic Kukama DAC and the JVC XL-Z1050TN CD player handle source duties. Audio Magic Illusions 4D speaker wires, interconnects and digital cable made the signal connections between the various components. The power cords used are from the Audio Magic Extreme series. With all the necessary components in place, I was looking forward to hearing what these unusual speakers are capable of.
Most reviews are written with boring “audiophile” approved songs. For this review I decided to try something a bit different and use music that is fun to listen to. That’s right, I am going to use the type of music that the average audio enthusiast listens to on an every day basis. In the last couple of years I have developed an appreciation for reggae. The only problem is that quite often I had trouble deciphering the lyrics on many songs. I always thought this was an issue with the recording, or that it was just a characteristic of the performance. A perfect example of this phenomenon is “Hotshot” by Shaggy. [Hotshot; MCA 088 112 096-2] Imagine my surprise when I cued this track up, and discovered that I could easily understand all the lyrics of this song. The midrange and treble drivers of the LFT-16 are fast and detailed, and are capable of uncovering all the subtle detail embedded in a recording. Equally important, these drivers are free of any noticeable coloration. When I compare them to my Audio Nirvana Super 12 speakers, I would have to say that the tonal balance of the LFT-16 is close to neutral, while the Super 12’s are noticeably forward in the upper midrange area. There is a level of quality and refinement to the midrange and treble spectrum of these speakers that belies their modest price. The midrange and treble drivers in this speaker are capable of reference quality performance, and I would place them at the top of the class for speakers residing in the sub $1000 category.
The hook in reggae music is the bass line. In a rock-n-roll band the lead guitarist is the featured performer, while in reggae the bass player gets all of the quality chops. Farther into the disc by Shaggy is a song named “Angel”. [Hotshot; MCA 088 112 096-2] The bass line of this track is smooth and melodic, and it compliments the vocal style of this song. In one of my early listening sessions I felt that there was an issue with the integration between the woofer and the higher frequency drivers. This tends to be a common issue in a hybrid speaker design, due to the fact that planar type drivers have a significantly lower driver mass than a conventional speaker. I specifically listened for this phenomenon, and was not surprised when I heard a slight misalignment between the two different driver types. During the early listening sessions, the bass line on “Angel” was always slightly out of step with the rest of the music. As time progressed, this issue began to resolve itself. In my final listening sessions of the LFT-16, the timing between drivers was no longer a problem. The 6.5-inch woofer is quick, and is well integrated with the planar drivers. The woofer needs more time to fully break in than the midrange and treble drivers do. I had not anticipated this turn of events, and did not keep a running tab on the amount of hours it took for the woofer to reach this point. If I had to estimate, I would say that the woofer needs at least 300 hours to break in.
The primary strength of planar speakers is their ability to create a large and stable image. Planar speakers portray acoustic space in a manner that other speakers are incapable of approaching. While the Eminent Technology LFT-16 uses relatively small planar drivers, they still have the characteristics of their larger brethren. “Back to the Rivers of Belief” by Enigma [MCMXC a.D.;Charisma V2-86224] is a fine example of what is good about electronic music. The opening portion of this track has percussive instruments that appear to resonate in a cavernous room. Later in this song, synthesizer notes fill the back wall of my listening room, and a mass of voices singing Gregorian chant vocals are projected in front of the speakers. The LFT-16 uncovers every layer of this song, and spreads them out for the listener to enjoy. There are very few speakers that are capable of displaying the electronic tapestry that Enigma creates, and the LFT-16 does this better than most speakers regardless of price. I have heard many speakers that cannot equal the LFT- 16 in this area.
Every moderately priced speaker will have limitations to their capabilities. The Eminent Technology LFT-16 is not an exception, and it is important to discuss the areas where this speaker has performance issues. Planar drivers have restricted dynamic range, especially when compared to a conventional driver. The LFT-16 is 85DB efficient with a 2.83 volt input signal. The maximum SPL rating is 103 decibels. To the listener, this translates into limited dynamic range on large-scale recordings. I could drive the LFT-16 to satisfying volume levels with the Monarchy amps, but they never had the impact, or the “jump” factor that the Audio Nirvana speakers present. The planar diaphragms are very light and responsive, but they are limited to how much air they can move. A buyer of the LFT-16 needs to know that they are trading off a degree of dynamic contrast for the speaker’s ability to resolve fine detail.
The second issue with the LFT- 16 is related to the size of the bass driver it employs. The .6.5-inch driver is quick and lively, but it is also limited due to its small cone area. Eminent Technology lists 45 hertz as the low frequency limit of this speaker, and my listening experiences tend to coincide with this parameter. The LFT-16 has good solid performance well down into the midbass region, but it does miss the lower registers that may be contained in a recording. The obvious solution is to augment the bass response with a subwoofer. One evening I installed an Audio Pro Avantek subwoofer into my system. With a bit of experimentation I had an acceptable integration with the LFT-16 speakers. It is important to use a high quality subwoofer, since a poorly matched speaker would just detract from the other strengths of the monitors. As an example, the soundstage in the Enigma disc became deeper and more precise when the Audio Pro subwoofer was utilized. Instruments that are located in the rear plane of the soundstage are responsible for producing the deepest bass passages. When the speaker system is unable to reproduce this information at the correct level, the depth of the soundstage is lost. As a general rule, all bookshelf size speakers will benefit from the addition of a subwoofer.
In a world where cones and domes dominate the small speaker category, the LFT-16 offers a refreshing choice for an audio enthusiast looking to take an alternate path. The Eminent Technology speaker has fantastic midrange and treble performance. Aside from its limited dynamic range, I cannot find any major fault with the LFT-16.. The bass performance of this speaker is respectable, especially when you take into account the small footprint of the speaker cabinet. The imaging capabilities of this speaker are quit a treat, and they surpass any speaker in the thousand-dollar price category that I am aware of. While some people may not embrace the unusual appearance of this speaker, it really is an audio gem that should be experienced by audio enthusiasts from all walks of life. The individual who has a modest budget to work with should be thrilled to use this speaker. While someone who owns a mega-buck main system can appreciate the abilities of this speaker in a modest secondary system. If you get a chance to listen to a pair of these monitors, by all means take it. You can’t help but appreciate the abilities of these fine speakers.
- A single sided driver has only one set of magnets that must control the diaphragm. As the driver reaches maximum excursion, the magnet structure has the least amount of control at this critical juncture.
- Electrostatic speakers use a Mylar sheet that is coated with a conductive material. The sheet is sandwiched between two acoustically transparent metal plates. A low current/high voltage charge is applied to the plates, which control the movement of the diaphragm. One characteristic of electrostatic speakers is low impedance dips, which place strain on the amplifier driving them.
- My Target TT-3 rack is really too small for a review system. I will be replacing them with a pair of Onix racks from AV123. These are very nice racks for a modest price.
from aﬀordableaudio, By John Hoffman