EMINENT TECHNOLOGY INCORPORATED LFT XVI HYBRID LINEAR FIELD TRANSDUCER LOUDSPEAKER REFERENCE MANUAL Revised: 12/28/05 Eminent Technology, Inc. 225 East Palmer Street Tallahassee, Florida 32301 Phone: (850) 575-5655 FAX: (850) 224-5999 Email: info@eminent-tech.com Website: www.eminent-tech.
Strong magnetic fields are present at and around this loudspeaker. Devices that are adversely affected by high levels of magnetic flux, such as television sets and pacemakers, should be kept at least three feet away from each speaker. Also, keep in mind when any ferrous objects are brought close to the speakers. Hold steel tools securely when setting up and adjusting the LFT-XVI, to prevent a hex key or screwdriver from slipping from your hand and damaging the Mylar diaphragm.
TABLE OF CONTENTS Installation of the LFT-16........................................................... 5 Unpacking the Speakers............................................................. 5 Speaker Assembly...................................................................... 5 Positioning the Speakers in the Listening Room....................... 5 Imaging...................................................................................... 6 The Tweeter Level Control......................................
Warranty.....................................................................................
Installation of the LFT-16 A complete technical description of the LFT-16 is included in this manual and begins on page 7. It is recommended that you become familiar with this information because an understanding of the LFT principals will assist you in the proper set up of these loudspeakers. The LFT-16 is shipped in one box. The box contains the two hybrid linear field transducer loudspeakers. Remove the padding from the top and remove the grill cloth frames, which are wrapped in cardboard.
position the speakers so that the main listening position is about on axis with each speaker. Slight mid-range frequency balance changes can be obtained by pointing the speakers slightly away from the listening position. Adjusting the speakers’ degree of vertical tilt with the pointed feet can also alter this balance.
The LFT-XVI is configured to allow bi-wiring or bi-amping with a minimum of trouble. Bi-Wiring and BiAmping Bi-wiring simply means connecting a single stereo amplifier (or two mono amps) to a pair of speakers by using two pairs of speaker cables. Connect the hot and ground conductors of a pair of cables to the same output terminals on one channel of the amplifier; the other ends are connected to the separate woofer and mid/tweeter inputs of the LFT-16 (All speaker cables should be the same length).
Technical Description The Eminent Technology Linear Field Transducer is a full-range, push-pull, dynamic planar loudspeaker. In a sense, it is the magnetic equivalent of a push-pull electrostatic loudspeaker, differing in that it requires no step-up transformer or bias voltage, and that the audio signal is applied directly to its diaphragm.
sandwiched between two stationary conductive grids (usually perforated metal plates) called stators. FRAME FRONT STATOR REAR STATOR [PERFORATED METAL PLATE] CONDUCTIVE DIAPHRAM TO BIAS VOLTAGE SUPPLY RESISTOR TO AMPLIFIER TRANSFORMER -+ PUSH-PULL ELECTROSTATIC [TOP VIEW CROSS-SECTION] Spacing exaggerated to show detail A DC charge of high voltage (in the thousands of volts) but very low current, known as the bias voltage, is applied to the conductive diaphragm and kept constant.
voice coil of a conventional cone driver). The diaphragm is held taut in a metal frame. On the front of this frame is a large sheet of perforated metal, to which rows of vertically aligned strip magnets have been fastened.
A ribbon driver is based on a long, narrow strip of conductive material; in practice, thus far, all true ribbons have used a strip of very thin corrugated aluminum for this purpose. The two ends of this strip are electrically connected to the amplifier’s output, and are physically anchored such that the strip is suspended within a stationary magnetic field--with said magnets positioned at the edges of the strip.
own colorations and non-linearities. Also, some ESLs are prone to a condition known as arcing: Under the conditions of stress induced by playing an ESL loudly, it is not uncommon for an electrical spark to jump between one stator and the diaphragm (a phenomenon exactly analogous to lightning), burning a minute hole in the diaphragm and, over time, ruining it.
construction of a high-quality loudspeaker*. It builds on the strengths of the above designs while eliminating many of their drawbacks. The construction of the LFT-16 begins by laminating a very thin sheet of aluminum foil to a half-mil-thick sheet of Mylar.
By applying such new techniques to planar loudspeaker construction, Eminent Technology has been able to eliminate many of the flaws inherent in earlier designs. Cloth is used on the backside of the speaker to resistively load the diaphragm. This lowers the Q of the diaphragms free air resonance. The use of a welded channel-and-crossbar frame dispenses with the need for perforated sheet metal (an “off-the-shelf” material presumably used for reasons of economy and ease of manufacture.
Panel Frequencies Each LFT-XVI has two individual driver panels and a cone type woofer. The placement of the individual drivers is shown in the following diagram. 7.5 KHz and above 250 to 7.5 KHz To 250 Hz General Specifications Power Requirements 25 Watts minimum Sensitivity 85 dB (pink noise, 20 - 20kH) at 1 watt/1 meter (2.
LFT-16 Impedance Curves Maximum SPL 103 dB at 1 meter Dimensions 9.75” wide by 21.5” high by 9.75” thick Shipping Weight 23 lbs. Each Warranty 3 years parts, 1 year labor Available Finishes Oak, Walnut, Black Painted Oak The LFT-XVI impedance is shown below. The impedance generally averages much higher than 8 ohms. This means that the speaker does not require a high current amplifier.
LFT-16 Impedance The impedance curves are shown for the woofer and mid-range/tweeter inputs Data connected. With the woofer section in parallel with the mid-range/tweeter section, the impedance curve becomes essentially flat with a minimum of about 5.5 ohms occurring around 100 Hz and a maximum of 30 ohms at 7.5 kHz. The 30 ohm peak is with the tweeter in its low output position. When the tweeter level is moved up, its maximum will drop to about 27 ohms.
Frequency Response The LFT-16 system 10Hz to 30Khz frequency response with the microphone at 1 meter is shown below. Low frequency irregularities are a result of the testing room. Near Field response of the tweeter including the crossover measured from 10Khz to 50Khz. This tweeter should please dogs and cats and is SACD ready.
LFT-16 MidRange Panel Specifications Magnet Type Ceramic 8 Mid-range Diaphragm area 35 sq in Foil Thickness 0.0007 in Mylar Thickness 0.0005 in Laminate Adhesive Thickness 0.00015 in Gap Between Conductors 0.03 in Peak-to-Peak Diaphragm 0.
Mid-Range Panel Design Do not attempt to disassemble these panels. The steel frame is preventing the panel from collapsing on itself. Removal of the cap screws that hold the panel together will surely cause damage to the diaphragm and may pinch hands and fingers. The mid-range panel design (shape and size) was chosen for good dispersion and bandwidth. For a given speaker design, there is a direct trade off between maximum sound pressure level, bandwidth and efficiency.
Box Volume 9.181 Liters 605 in3 .687 ft3 Speaker Diameter 6.5 inch Magnet weight 20 oz. Impedance 6 Ohms Re 6.35 Ohms Le 0.60 mH fs 24.5 Hz ±15% Mmd 21.8 grams Mms 22.
Additional Woofer Specifications Vas 46.8 Liters QM 2.77 QE 0.31 QT 0.28 Bl 8.47 Tm Xmax 4.25 mm Pmax 75 Watts Coil Diameter 1.5 in Gap Height 0.25 in Efficiency 0.22% SD 133.1 cm2 VD 56.6 cm3 EBP 79.3 Rms 1.258 N*sec/m Cms 1.
The design goal for the woofer is good transient response, low Q, low cutoff frequency and minimal coloration near the crossover region. In a hybrid system of this type, it is desirable to have as low a crossover frequency as possible for the woofer. Because of these factors we chose to design our on woofer. An six and half-inch woofer was chosen because it offered the best balance between low frequency response, the size of the box and blend with the mid-range driver.
(2) To provide sufficient internal volume to give the desired frequency response. (3) To visually appear smaller than it is when attached to the rest of the speaker. Research has shown that even if the resonance levels of an enclosure are 40 or more dB below the signal levels of the woofer, they will still be audible because their harmonic structure is almost always different than that of the signal coming from the woofer itself.
postmarked no later than one month after the date of purchase), the above warranty will be extended to three years for parts and one year for labor. This warranty is transferable to subsequent owners, pending notification from the original owner, in writing, within 10 days of the personal sale. The obligation of Eminent Technology under the terms of this warranty does not extend to: 1. Any LFT-XVI installed or operated without regard for the instructions contained in this manual. 2.
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