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RE: ET LFT-8b in Harry Weisfelds system

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sbrook@cfl.rr.com

In Reply to: RE: ET LFT-8b in Harry Weisfelds system posted by Davey on June 19, 2017 at 18:59:45

What specifically are the issues to which you allude and to which model? The LFT8 has gone through a few revs which includes woofer and tweeter changes. I have 2005 set of 8A's with field upgraded 8B tweeters. They have deficiencies as does any speaker but I have been very happy with them for over a decade.

Follow Ups:

RE: ET LFT-8b in Harry Weisfelds system - BDP24 20:51:02 06/21/17 (4)
sbrook---the woofer problem is a matter of the driver having a resonant peak way above it's 180Hz x/o frequency, which because of it's shallow 1st order slope is audible. Davey came up with a cure for it, adding a couple of electronic parts to bring the woofers response at that resonant frequency down to the point of inaudibility. He will provide the specifics for the filter he came up with if you ask him, I believe. It is buried in this forum somewhere too. The woofer problem is found in all three versions of the LFT-8.

The output level of the tweeter was increased in the "b" version of the speaker, in response to complaints of the LFT-8 and 8a having a too soft high end. Davey feels otherwise, finding the b version to sound to hot for his liking. Others feel differently, for the usual reasons.
- RE: ET LFT-8b in Harry Weisfelds system - sbrook@cfl.rr.com 08:30:24 06/22/17 (3)
  Interesting. I have never heard the woofer squeal. My only complaint about the woofer is overall output but that is also a function of my large irregular room (as are so many things). I run them full range with the secondary output on my preamp feeding a B&W ASW1000, lp at 40Hz, gain just barely up. It fills in the bottom octaves but on some recordings I even have to turn it off.
  
  I found the newer tweeters to be an improvement if only because of the backing material on them. No comment on the new magnet structure, I run them on the high setting.
  
  I think that the alchemy of room, ears, and equipment is always in play. All tube driven, 4000+ cu ft carpeted room with glass sliders ~36" behind and a vaulted ceiling. Hearing attenuation for 50+ years of usage so my HF perceptions aren't going to line up with someone perhaps a lot younger.
  - RE: ET LFT-8b in Harry Weisfelds system - BDP24 12:23:01 06/22/17 (0)
    Ultimately, Davey found the LFT-8b unsatisfactory, and sold his pair on Audiomart (I was tempted to buy them and used them stacked with my pair, but found a pair of Tympani-IVa's, spending the money on them instead ;-). A demanding fella, that Davey!
  - RE: ET LFT-8b in Harry Weisfelds system - Davey 09:10:11 06/22/17 (1)
    If you'd like to experience the squeal just play the woofer section by itself and use a sine track that sweeps slowly up through the frequency range. When you get to the 2khz range you will have to plug your ears, I promise. It's highly irritating. :)
    
    Dave.
    - RE: ET LFT-8b in Harry Weisfelds system - sbrook@cfl.rr.com 10:14:05 06/22/17 (0)
      I imagine that would be extremely irritating. But if I am understanding this issue correctly then the crossover is not doing a proper job of keeping the woofer from having significant output well outside of the frequency range for which it was designed.
      
      Can you observe this phenomena with regular musical material?
RE: ET LFT-8b in Harry Weisfelds system - Davey 16:20:00 06/21/17 (0)
I've outlined my issues (and fixes) in numerous previous posts.
The woofer squeals horribly in the 2khz range, and the later version tweeters are much too hot even with the "low" position selected.
I also don't think the relative polarity of the tweeter/midrange is correct.
My speakers were later version LFT-8b's.

If you're happy with your iteration, that's all that matters. Enjoy them.

Dave.

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