Welcome! Need support, you got it. Or share your ideas and experiences.
In Reply to: RE: Parts Express announces full line of NEO drivers posted by Utley1 on October 10, 2020 at 13:22:25
No, the Eminent Technology LFT-8 uses drivers all designed (in the 1980's) and made by Bruce Thigpen. LFT stands for Linear Field Transducer, which describes one element of the driver's design: Unlike the single-ended Magneplanar drivers (magnets on only one side of the Mylar), the LFT has magnets on both sides of the Mylar, creating a magnetic field in which the force remains constant regardless of the excursion and location of the vapor-deposited conductive traces on the Mylar (while the Maggies have actual wire as conductors, the LFT uses a lower-mass coating as a conductor. It looks like the traces on a circuit board).
There are two LFT drivers in each LFT-8 (one above the other), which reproduce 180Hz up to 10kHz---with no crossover in that frequency band! A single ribbon tweeter handles 10kHz and up, a single 8" dynamic woofer in a sealed enclosure 180Hz and lower, both with 1st order filters. 5' tall by 13" wide. $2499/pr.
Edits: 10/10/20Follow Ups:
Thank you-very clearly expressed. Are the Thigpen drivers long lived?
Utley, that is another advantage of the LFT. The vapor-deposited conductive element does NOT exhibit the delamination the Maggie conductive wires do. None. Or any other problems. The driver has been in production for over 30 years, with not a single change!
The LFT-8b has about the same sensitivity as the smaller Maggies (lower-to-mid 80's), but is an easy 8 ohm load. The LFT driver itself is an almost perfect 11 ohm resistive load, great for tube amps. That allows the LFT-8b to be used with two moderately-powered amps, tube for the panels, SS for the woofer. The 8" woofer integrates very well with the panels, unusual for a hybrid. It also produces much lower in frequency (and output) bass reproduction than do the smaller Maggies.
The LFT-8b has received raves in the UK press, and from Robert Greene in TAS. VPI's Harry Weisfeld said it has the best midrange of any loudspeaker he has ever heard, regardless of price. A ridiculous bargain at $2499/pr. There are very few ET dealers, but Bruce offers a money-back trial audition for factory-direct purchases.
"The vapor-deposited conductive element does NOT exhibit the delamination the Maggie conductive wires do."
Since when do they use vapor-desposited traces? They used a laminate:
Foil thickness .00033"
Mylar thickness .0005"
Laminate Adhesive Thickness .00015"
Roger, your post prompted me to get out my owners manual, which has a lot of technical details on the design of the LFT-8b. Awhile back I somewhere read that the conductive material was vapor deposited onto the Mylar of the LFT driver, but you are absolutely correct: whomever wrote that was mistaken (and therefore so was I), because here is what is written in the manual:
"The construction of the LFT-8b begins by laminating a very thin sheet of aluminum foil to a half-mil-thick sheet of Mylar. A voice grid pattern, created by means of CAD (Computer-Aided-Design) technology, is silk-screened onto the foil side, the remainder of the aluminum---the part not covered by the ink from the silk-screening---is etched away, in a manner similar to the etching of traces on a printed circuit board. The ink is then washed away, leaving a voice grid of near-perfect uniformity. This technique results in a diaphragm/voice coil grid that is still less than one mil in total thickness, and also permits relatively narrow spaces between the individual traces, so the diaphragm can be evenly driven over its entire surface."
Phew! The next paragraph in the manual goes on to describe the design and construction of the magnetic structure of the driver. I am very impressed by the design and build of the LFT driver, quite a bit more sophisticated imo than the m-p drivers in Maggies.
At any rate, the point is the LFT driver has proven itself to be free of the lamination problems older Maggies develop. One may buy an older used (or new) LFT-8b without fear of the repairs many older Maggies require.
BTW, there is extremely little delamination history on any of the Magnepan QR panels (foil on mylar, just like the ET), or on the round wire panels manufactured after 2005, after the factory changed the glue formulation used.
The numbers I listed above seems to be a standard laminate available from many sources. I have a roll of it somewhere. Vapor desposiited Mylar use to have a very thin layer of conductive metal. It will probably not work well in a planar driver of this kind.
Post a Message!
This post is made possible by the generous support of people like you and our sponsors: