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TUBE-TECH SMC 2B/M
Stereo Multiband Compressor
Description:
The TUBE-TECH multiband compressor SMC 2B/M is three-band stereo compressor.
The two x-over frequencies are each made with a single RC circuit thereby preserving
optimum summation of the three bands at the output.
The x-over frequency between the low band and the mid band is variable from 60Hz to
300Hz or 240Hz to1200Hz and the x-over frequency between mid band and the high band
is variable from 1,2kHz to 6kHz.
The signals from the three bands are then fed to the three separate side chain circuits,
each common for left and right channel. After processing, the three signals goes to a gain
control, separate for each band and, are thereafter summed and send to the output gain,
controlling the entire output level for all three bands.
Compressor:
The compressors are of the optical device type. It has controls for ratio, threshold, attack
and release.
COMPRESSOR CONTROLS:
RATIO: The ratio control varies the ratio by which the input signal is compressed.
If the ratio selected is 2:1, and the input signal increases 10 dB, the output
signal is only increased by 5 dB.
The ratio control is continuously variable from 1,5:1 to 10:1.
THRESHOLD: The threshold is the point where the compressor begins to respond.
It is defined as the point where the gain is reduced by 1 dB.
The threshold is continuously variable from off to -20 dBU.
ATTACK: The attack control chooses how fast/slow the compressor responds to an
increase in the input signal.
The attack control is continuously variable from 3 to 200 milliseconds.
RELEASE: The release control chooses how fast/slow the compressor responds to a
decrease in the input signal.
The release control is continuously variable from 0,06 to 2 seconds.
COMP in/out: This switch controls a relay that bypasses the whole unit.
(131113)
Lydkraft ApS
Mose Allé 20, DK2610 Rødovre
Denmark
2
OUTPUT GAIN:
The gain control is used to "make up" for the gain loss, which takes place
when the unit is compressing. The gain control is continuously variable
from off to +10 dB.
BALANCE:
The balance control is used to compensate for the difference between
channel 1 and channel 2. The balance control has a range of +/- 1,5dB.
(030318)
Lydkraft ApS
Mose Allé 20, DK2610 Rødovre
Denmark
3
ADJUSTMENT PROCEDURE:
CAUTION:
Before making any adjustment let the unit heat-up at least 10 min.
Always check the DC voltages at the power supply.
1) The DC voltage in TP201 shall be +280V (265-295).
2) The DC voltage in TP203 shall be +15,0V (14,7-15,3).
3) The DC voltage in TP204 shall be -15,0V (14,7-15,3).
ADJUSTMENT OF PSU:
1) The DC voltage in TP202 shall be +240V.
Adjust with P202.
THE GRE SHALL BE MARKED 1.005-1.175
ADJUSTMENT OF BASIC GAIN:
1) Set the “OUTPUT GAIN” on “+10”.
2) Set the Low-Mid and High “Gain” on “+10”.
3) Apply a signal of 1 kHz, -20,0 dBU to input.
9) Adjust the preset “Gain” P1 (P101) (on amp/psu PCB) to an output reading of 0,0 dBU.
ADJUSTMENT OF COMPRESSION:
LOW BAND:
1) Turn all the THRESHOLD-controls fully counter-clockwise.
2) Turn the LOW BAND GAIN-control fully clockwise.
3) Turn the MID BAND and HIGH BAND GAIN-control fully counter-clockwise.
4) Set the X-OVER LOW at 300 (1,2k).
5) Set the X-OVER LOW multiplier at x4. (030318)
Lydkraft ApS
Mose Allé 20, DK2610 Rødovre
Denmark
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