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| KLH (Burwen Research) TNE 7000A Modification (Modification) | Sep 12th, 2012 | Vince, the shop owner, worked as the chief technician at KLH/Burwen Research and knows this equipment inside and out. Recently he was asked to possibly update and improve this unit. People knew it worked fairly well, but possibly better. Vince modified the click sensor circuit to gain ride the audio ticks to allow easier and less critical “sensitivity” and “threshold” adjustment, so that the unit tolerates a greater range of audio level coming through without false “de-clicking” of audio transients. It is important to note that even in its era, Dick Burwen commented that a phono cartridge and preamp combination must be able to go out to 25kHz with reasonably correct phase response. The best cartridges were elliptical, hyper elliptical, and shibata (line contact) stylus type made by Audio Technica, Stanton, Shure, and possibly Grado on only their better cartridges (ie $60 and up typical retail). Surprising many fancy name cartridges could not do the basic job. The best results to de-click the record noise is done with such devices. It is best to come out the tape monitor record circuit on a receiver then input to the TNE. Then back into the monitor playback in the receiver for listening to the TNE.
16 stages of op amps are required to do the time delay trick to remove transient pops. The units we sell all have upgraded op amps (much needed due to the amount of op amp stages) and power supply changes, as well as fine tuning the FET switching circuit. Other mods are done which improve the unit, The TNE will have TL075 op amp installed (lower noise, measurably lower distortion than the original 4136 op amp). There will be an improvement as to ranging of controls, in consideration with the better phono cartridges most people use today. In fact, the performance improvement of the TNE relies upon the use of a true wide bandwidth, fast rise time cartridge, to provide clean impulse phase response to trigger the TNE. These TNE units would originally get about 25% of the obvious clicks and pops out. Oddly, the out of phase (channel to channel) clicks are removed more readily. Vince's modification will track and eliminate more, but critical front panel control setting, record to record is still required. Vince is presently further modifying the unit so it will “gain ride” the incoming nicks so as not to overload the de-clicker circuit. This dramatically improves performance and reduces false de-clicking. The basic mod also somewhat improves the audible de-clicked “chop out” of the signal. The unit now performs better and removes 50% of nicks and pops. It still doesn't get everything, but it gets much more and does it less obviously.
The TNE 7000A is best suited and designed for removal of fine nicks and pops. Extreme nicks and pops, such as those on 78 records, will not be removed effectively unless an unusual modification is done to the unit. Strangely, the SAE 5000 does a better job at the heavy handed transients on 78 records, but is insufficient at low level nicks. Often such noise is really vinyl hash from die cracks when records are pressed on microgroove or dynagroove records etc., and, of course, general minor scratches.
All Burwen TNE7000 units are now modified to perform better and are priced at $380. The modification alone costs $150 plus return shipping.
For current availability, give us a call-- (617)926-8020. |
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Monday (12 Noon - 6pm),
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Wednesday through Friday (11am - 7pm),
and Saturday from (11am - 3pm).
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** Employment Opportunity - Technician Needed (2012-10-12) **
We are currently looking for a Technician, with experience in Audio.
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Please do not ship any packages to us using the Fed Ex Home Delivery Service
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Unless described otherwise in the item listing, all items have been cleaned, serviced, and tested for correct functionality on a professional test bench. Items listed as parts are sold as is.
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| Full Article Details | Saturday, May 25th, 2013 |
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