Tube Tech LCA 2A Stereo Compressor - Manual (Page 5)

LYDKRAFT Aps
Ved Damhussøen 38, DK 2720 Vanløse
Denmark
ADJUSTMENT OF DISPLAY:
1) Turn the THRESHOLD-control for the compressor and limiter
fully counter-clockwise.
4) Apply a DC-voltage of +5,000 V into the sidechain jacksocket
(tip).
5) Set the LINK-switch at LINK 1 and observe that the -13 LED
just turns off and the -20 LED is on
6) If this is not the case, adjust P 8 (P108) at the sidechain
PCB.
ADJUSTMENT OF BALANCE IN THE VCA TUBE (V1, V101):
1) Turn the THRESHOLD-control for the compressor and limiter, and
the GAIN-control, fully counter-clockwise.
2) Switch the LINK-switch to LINK 2.
3) Apply a sine wave of 1 kHz, +15 dBm via a 1K
Ω resistor into
the sidechain jacksocket (ring).
The +15 dBm shall be measured before the 1K
Ω resistor. *
4) Adjust trimpot P2 (P102) (located on amp/psu PCB) to a minimum
reading at the output.
5) Reduce the level of the sine wave to -5 dBm.
6) Adjust trimpot P1 (P101) (located on amp/psu PCB) to a minimum
reading at the output.
7) Repeat step 3 - 6.
8) When both adjustments are at minimum, the level at the output
in step 4, shall be lower than -20 dBm. If this can not be
obtained, the VCA tube shall be rejected and replaced with new
one.
* If the sine wave from the oscillator is observed on oscillo-
scope after the 1K
Ω resistor, the negative part of the sine
wave have been clamped to ground and will therefore be mis-
sing.
The balance adjustment of the VCA, should be carried out every
6 month.