Burwen TNE 7000A
Transient Noise Eliminator

Excerpt from Users' Manual


Jay's Note: This is the most critical part of the instructions that came packed with the TNE 7000A, in my opinion the best practical record-click eliminator ever sold. It's reprinted here by permission of the inventor, Dick Burwen.

It was also hand-typed into html, so please forgive any typos.

Dick does not want to be bothered with questions about this device. If you can't find an answer here, you're on your own.

Service manual and circuit description.


OPERATION

  1. Before turning your receiver or preamplifier on or off, turn your volume control to 0 or set the tape source switch at "source" on your preamplifier or receiver. This elminates a turn-on or turn-off thump. If your preamplifier has a built-in time delay, the thump will automatically be avoided, regardless of the control settings.
  2. Make the following intial setting of the controls on your TNE 7000A:
  3. Adjust the SENSITIVIty and THRESHOLD controls in accordance with the following sections:

SENSITIVITY CONTROL

The SENSITIVITY controls adjusts the sensitivity of the detector circuit to high-frequency program information. When the SENSITIVITY control is set at maximum counter-clockwise, the Transient Noise Eliminator 7000A is at minimum sensitivity to high frequency information. This control should be set during a record passage where there is enigher no musical content or only low frequency music, such as a bass guitar. With SENSITIVITY at the maximum counter-clockwise position,the HIGH FREQUENCY CALIBRATION LED is brightly lit. Advance the SENSITIVITY control clockwise until the HIGH FREQUENCY CALIBRATION LED is only dimly lit. At this point, the LED is beginning to show the effect on the detector circuit of the high frequency hiss level in the signal. This is the best setting for the control High frequency hiss is alsmost always present in the audio signal and your Transient Noise Eliminator 7000A is now tuned for this lowest level high frequency signal. The TNE is ready to be adjusted to eliminate the high frequency transient noise by using the THRESHOLD control. Do not turn the SENSITIVITY control beyond this point except for certain types of program material, as explained under FINE CALIBRATION. When the SENSITIVITY control is set at maximum clockwise, the TNE 7000A is at maximum sensitivity to high frequency information.

THRESHOLD CONTROL

The THRESHOLD control adjusts the sensitivity of the detector circuit to music and to ticks and pops in the presence of loud high frequency program information. Whent he THRESHOLD control is set at maximum counter-clockwise, the Transient Noise Eliminator 7000A is at minimum sensitivity to transient noise and to music. The control should be set during a record passage where there is medium to loud high frequency musical content, such as violins and the upper ranges of brass. With THRESHOLD at the maximum counter-clockwise position, the TRANSIENT NOISE ELIMINATION LED is not lit. Advance the THRESHOLD control clockwise, and the TNE 7000A will begin to eliminate those noise impulses that are audible above the music. The TRANSIENT NOISE ELIMINATION LED will flash each time t he Eliminator removes a tick or pop. The Elimintor distinguishes between transient noise and high frequency music by detecting the sharply erratic signal of the noise, as opposed to the more slowly varying musical patterns. As you adnance the control clockwise, the TNE elminates a higher proportion of ticks and pops. Set the THRESHOLD control by ear at the maximum clockwise setting that does not cause audible distortion. Beyond this point, the TNE will be activated by the music, distorting the signal. When the THRESHOLD control is set at maximum clockwise, the 7000A is at maximum sensitivity to high frequency noise and music. (Note that the TRANSIENT NOISE ELIMINATION LED flashes on for approximately 17 thousandths of a second each time a tick or pop is removed. To make the flash of light appear bright enough, the duration of the light impulse may be more than 200 times the actual time the audio signal is turned off to eliminate the noise impulse.

FINE CALIBRATION

For certain types of program material, the SENSITIVITY control can be used advantageously when advanced in the presence of high frequency music. On worn records with loud brass instruments, for example, the maximum clockwise setting can be used to prevent false triggering by the distortion components of the brasses. The detector will then saturate on the loud high frequency content and prevent false triggering on loud cymbals and other transient high frequency music.

Use the TRANSIENT NOISE ELIMINATION LED as a guide in setting both the SENSITIVITY and THRESHOLD controls. At the optimum setting, the frequency of flashing causes by the elminiation of ticks and pops is about the same during medium volume signals as during the silent portions of a record. You will hear no effect on the music, while noting the elimination of the transient noise. If the two controls are incorrectly set, so the detector operates too frequently and is activated by the msuic, the music will sound chopped up and distorted.

Occasionally you may notice the TRANSIENT NOISE ELIMINATION LED flashing in synchronism with certain types of percussive musical material such as cymbal beats. Since the KLH BURWEN RESEARCH Transient Noise Eliminator operates by detecting unusual amounts of ultrasonic frequency content in the vertical component of the phono signal, it cannot always distinguish between the onset of a transient noise and the onset of a musical transient such as a cymbal beat. When the controls are properly set, even if the circuit does trigger on the leading edge of a cymbal beat, the signal is turned off for only 1 to 2 thousandths of a second. There is no audible musical loss.

Very loud high frequency signals may cause the TRANSIENT NOISE ELIMINATION LED to stop flasing altogether. At such high levels there is usually no need to eliminate the ticks and pops, since these are obscured by the music.

The TRANSIENT NOISE ELIMINATION LED may flash very seldom when playing a new high quality record, but even the best record will have imperfections in the vinyl that can cause transient noise. On the other hand, the TRANSIENT NOISE ELIMINATION LED may be on almost continuously onan old worn record. If the LED is on continuously, it indicates that the intervals between transients are less than 17 thousandths of a second. It does not mean the signal is continuously interrupted.

In some sound systems it is possible for the TRANSIENT NOISE ELIMINATION LED to light continuously even when there is no music. This may be an indication of a 60 Hz buzz being picked up in your phono preamplifier system from some noise source such as a light dimmer. If the effect on your program material is audible, reduce the setting ont he SENSITIVITY control so the LED flashes only on ticks.

To determine whether there are any remaining audible effects on the music, press the DEFEAT switch and compare the processed signal with the unprocessed signal.

Although the TNE 7000A will substantially eliminate transient noise, resulting in vastly improved record performance, severely damaged records with dirt ground into the surfaces may be beyond the performance restoration capability of any noise supression technology available today. Signal processing cannot always restore worn vinyl to high performance condition.


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March 15, 1998
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