This is for TWO UNITS: a vintage KLH Burwen Research Transient Noise Eliminator, model TNE 7000A, and a noise filter, model DNF1201A. Tested, working, sold as is.
These devices are vintage rackmount pro audio equipment designed to eliminate transient noise (clicks and pops in vinyl) and unwanted sound (hum, hiss, crackle) in recordings. The brand is known for producing high-quality analog audio equipment that was popular among professionals in the industry.
The following is for reference, from a defunct site by Jay Rose:
Burwen TNE 7000A Transient Noise Eliminator Excerpt from Users' Manual
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.
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.
The TNE7000 appeared in the early 1980s, and was the first (and in my opinion best) unit to remove ticks from phono playbacks. We put one in every studio in our facility. This copy of the service manual is posted both for public education and to help those who have one of these units. It's (c) 1980 by the inventor, Dick Burwen, and was graciously supplied by him. It was also hand-typed into html, so please forgive any typos.
CIRCUIT DESCRIPTION
Following A102B is a single pole double throw electronic switch Q102. Normally Q102 acts as a short-circuit (approximately 50 ohms) and allows the signal to pass through Q102C acting as a follower. During a tick, diode D102 cuts off Q102 and the signal path to Q102C comes from TPIOI via R129. Low distortion in normal operation is achieved by maintaining the gate of Q102 midway between the source and drain via restators R128 and R131. The frequency response and gain effects of the small series resistance are compensated by providing a 3% loss in the feedback path by means of R130 and R142. These components, together with R129 and the series resistance of Q102 make A102C a bridge amplifier which, in normal use, accurately amplifies with a gain of 1.0 the signal at the output of A102B. The final output amplifier A102D contains a complementary deemphasis network in its feedback path consisting primarily of C120, R137, and R138.
The comparator A304A is an open collector type wand uses R337 and C311 for a load. This rc combination provides a 60us off delay which is then sensed by the comparator A304B whose output is used to operate the electronic switches Q101 and Q102 in the left channel and Q201 and Q202 in the right channel. When a tick comes along, the switch off time typically varies in the range from 60 to 600 us and occassionally up to 2ms. In order to make the tick supression LED P302 visible, the pulse is stretched by network R340 and C112 at the output of comparator A304C so that comparator A304D will turn PL302 on for approximately 16ms for each tick.
If the transient noise elimination LED cannot be made operate on the leading edges of the square wave, the trouble is likely to be in the detector circuit. If this LED operates and there is no audio output, look for trouble in the audio channel.
The last test is to observe the nosie output on one channel when triggered by a square wave on the other channel. Feed a 100Hz square wave at 0.775 v rms into the left channel. Adjust the Sensitivity and Threshold controls so the Transient Noise Elimination LED lights up. Observe the nosie output on the unused channel when the horizontal trace is synchronized with the leading edge of the square wave. Also, listen to the unused channel on headphones. If there is a small noise, this may indicate drift in the zero adjustment potentiometer R232 which can be reset to minimize the noise. The level of noise on the oscilloscope, neglecting a spike of a few microseconds duration, is normally approximately +/- 1 mV and lasts for 80 ms. A very large noise may indicate trouble in the switching portion of the circuit incluidng A202B, Q202, Q201, Q203A, or Q203B. If there is a large noise at no signal input, check the dc output at TP201 which should be 0. Next interchange the inputs and check the other channel.
If there is trouble in the power supply which may be indicated by no CAL light, check the +/- 15V output of the regulators. If a fuse is blown, find the cause of the blown fuse before replacing the fuse and turning the unit on again.