Jun 1st, 2018
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 a TL075 op amp installed (lower noise, measurably lower distortion than the original 4136 op amp). However now our circuit is being modified to adapt to the original op amp. With the new mod 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 settings within the record track better but, record to another record still requires calibration of front panel controls. 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 new mod also somewhat improves the audible de-clicked “chop out” of the signal. The unit now performs better and removes 70% 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; call for availability. The modification alone costs $220 (with TL075 op amp modification) plus return shipping.
New, updated, further information: (June 1st, 2018)
First off, many of these TNE machines come in with other problems which are usually easy to solve but sometimes I charge more, especially when wrong op-amps have been installed.
Secondly, certain type op amps (although older types) must be installed in the “delay line”. This has to do with the exact time phase synchronization of music with the tick and click detection circuits which are also “timed” to correctly trigger the “blanking” and equalizer filter FET circuits. Those op amps pass no audio which is heard by the listener, they just control signal shaping, d.c. control, etc. No reason to change them unless they are failed. Amateurs who don't understand these circuits can create stupid ideas based on beliefs that certain op amps sound better or worse. Simply put, these concepts have no validity in terms of this design.
Thirdly, the circuits which must delay the audio have many op amp stages of an older “4136” op amp and while it is true that better op amps should be put in and indeed, audibly it can make the “fidelity” slightly better the problem is the design is specifically set for a certain time, delay, equalization, etc. So I can only match these op amps based on noise & distortion. A rare TLO75 op amp can be retrofit but now requires other parts to be changed as well. The I.C. Leg/socket type installed originally accommodates very few substitutes. Its not worth the effort or expense, considering that... number 4 (QED) truly more audible improvements are accomplished with my modification of the actually TNE circuit... for virtually inaudible and better more stable calibrated circuit now exist which allows forcing the TNE to “gain limit”, & now control more carefully, dig deeper to get more troublesome ticks out, work better with more cartridges, stay in calibration over a wider dynamic range of music, especially song to song within the record.
As an overview, a better (not more expensive!!) cartridge will improve fidelity and TNE operation also. I worked with Dick Burwen, he brought me into the Burwen engineering. After I had improved his tape noise reduction design , I helped to operate the calibration line at KLH. Finally, the reason I write this letter is to clear out many questions so many people have asked, and simply put- to date, not one person has complained that the TNE was not improved with my modification except when certain goofy cartridges or non-standard pre-amps (which plague the audiophile market) were used, and that is a touchy subject which for some people seems to get them annoyed. Specifically, many Ortofon cartridges and many moving coil cartridge designs are in fact not well done when crucial parameters such as channel separation (some cartridges are as little as 15db separation of left to right & will not correctly trigger the TNE circuit consistently) some moving coil cartridges have bizarre frequency response or false nulling of center channel information (which can cause recording to sound “airy” or “spacious”) but confuses the TNE detection circuits. In general phono cartridges with .3 by .7 millimeter stylus or shibata or hyper line contact design will work best and retrieve the best fidelity from the groove, as well, not transmit the bottom groove ticks. This helps to clean up the sound also.
For current availability, give us a call-- (617)926-8020.