Tube Tech CL 1B User Manual
1
TUBE-TECH CL 1B
Compressor
DESCRIPTION.
The TUBE-TECH compressor CL 1B differs from many other compressors, in that the gainreduction element is made from a non-semiconductor element, which in itself has a very low
harmonic distortion and none of the non-linearity problems involved when using most
semiconductor elements. Furthermore there is no long-term degradation of the element thus
giving it almost infinite life. This element is placed after the input-transformer of the compressor
and followed by an all tube-based amplifier with a gain of -dB to +30 dB.
Thus the signal is not fed through any semiconductor circuitry on its way to the output.
The amplifier consists of two tubes (valves) in push-pull configuration (one ECC 83 as the
pre-amp and phase splitter, and one ECC 82 as the output stage), and an output transformer.
The power supply for the pre-amp and phase splitter are stabilized and the heaters of both
tubes (valves) are fed with a stabilized DC voltage.
The whole amplifier (including input and output transformer) and the power supplies are placed
on one PC-board.
Both input and output are balanced (600) and fully floating.
The in/out key switches the compressor in and out without clicks.
THE SIDECHAIN:
The side chain is the only part of the compressor that contains semiconductors. They are used
for three reasons: First they do not affect the sound reproduction, second they have a high slew
rate, which is of importance for the performance of the compressor and third they don't take up
much room.
It contains two J-FET quad op-amps, one npn-transistor and one FET-transistor, which handles
the signal for the gain-reduction element.
The compressor contains two time constants circuits:
1. Fixed attack and release times
2. Variable attack and release times
The
attack/release select
combine their functions.
This gives a feature not normally obtained in other compressors:
In the combined (fix. /man.) state the attack- and release controls makes it possible to
obtain a complex release-time slope. (See page 4)
switch makes it possible to use these two circuits separately or
(980112)
LYDKRAFT ApS
Mose Allé 20, DK 2610 Rødovre
Denmark
2
COMPRESSOR INTERCONNECTION:
The side chain sockets for interconnection of several compressors are located on the rear
panel.
A switch (BUS SELECT) on the front selects which compressors are interconnected, and on
which bus they are connected. If you e.g. have 10 compressors in a rack, you can select
compressor 1,5,7 and 8 on bus 1, and compressor 2,3,6 and 9 on bus 2, leaving compressor 4
and 6 in the off position.
Compressors 1,5,7,8 are now interconnected and all four will perform the exact same
compression. This applies to compressor 2,3,6 and 9 as well. Compressor 4 and 6 are
independent.
The interconnection implies, that the unit, which performs the most compression, is controlling
the others.
To choose which one you want to control, select the attack/release time, the threshold and the
ratio on that unit, and turn the threshold fully counter clockwise on the reminding compressors.
It is of course possible to have all the interconnected compressors control each other
simultaneously.
NB:
Remember to set the ratio control and the gain control in the same position on the
"slaves". Otherwise the stereo image could be shifted during compression. The
attack/release-control on the slaves will have no effect.
The input/output capability of the side chain-circuit allows up to
compressors to be linked
ten
together.
They are connected in parallel with a standard 1/4" stereo jack/-jack cord (tip: bus 1, ring: bus
2).
The two jack socket on the rear panel is connected in parallel and both are input/output.
(980112)
LYDKRAFT ApS
Mose Allé 20, DK 2610 Rødovre
Denmark
3
CONTROLS:
GAIN:
RATIO:
THRESHOLD:
METER:
The
control is used to "make up" for the gain loss, which takes place
gain
when the unit is compressing. It is placed after the gain-reduction circuit
and therefore has no influence on the threshold setting. The
gain
-control is
continuously variable from off to +30 dB.
The
control varies the ratio by which the input signal is compressed.
ratio
If the ratio selected is to 2:1, and the input signal increases 10 dB, the
output signal is only increased by 5 db. The
control is continuously
ratio
variable from 2:1 to 10:1.
The threshold is the point where the compressor begins its action. It is
defined as the point where the gain is reduced by 1 dB.
The threshold is continuously variable from +20dBU to -40 dBU.
The VU-meter switch has three positions:
1.
2.
Input
Compression
The meter is reading the level at the input socket.
The VU-meter is reading gain reduction.
Its rest position is "0 VU", and the amount of
compression is shown as a decreasing deflection in
dB.
IN/OUT:
ATTACK:
RELEASE:
3.
Output
The VU-meter is reading the level at the output socket.
"0 VU" is equivalent to +4 dBU.
NB:
Leave the meter switch in position
introduce distortion if left in the
inputoroutput
compression
as it might
position.
This leverswitch switches the compressor in and out of the signal path. The
out position bypasses the entire compressor.
The
attack
control chooses how fast/slow the compressor responds to an
increase in the input signal.
The attack control is continuously variable from 0.5 to 300 milliseconds.
The
release
control chooses how fast/slow the compressor responds to a
decrease in the input signal.
The release control is continuously variable from 0,05 to 10 seconds.
(980112)
LYDKRAFT ApS
Mose Allé 20, DK 2610 Rødovre
Denmark
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