Tube Tech LCA 2B User Manual
1
UsersManual
TUBE-TECH LCA 2B
compressor and limiter
DESCRIPTION:
The TUBE-TECH LCA 2B is a two-channel unit with an independent compressor and
limiter per channel. The unit is all tubebased (except for the power supply and sidechain circuit). Output gaincontrol is placed be tween the VCA and output stage. The
VCA (1 dual triode) is placed between the input transformer and the output stage (2
dual triodes). The audio signal is picked up after the VCA and fed to the sidechain
circuit. The control signal from the compressor and from the l imiter is combined and
sent to the link switch and to the control amp, which feeds the VCA. The bi-directional
link busses are accessible at two 1/4" stere o jack sockets on the rear panel. The
channels can be linked together f or stereo applications and also linked to other LCA
2B's via the two link busses and a standard stereo jack/jack cord.
The co mpressor has six attack/release pr esets as well as manual control.Thelimiter
attack/release is fixed and equipped with an on/off switch.
The L ED display is fed from the control amp. The l imiter LED is fed from the li miter
buffer.
The a udio path is fully symmetrical from input to output.
Input and outpu t have fully floating transformers.
All DC voltages are stabilise d, except the anode voltage for the output stage, which is
only fi ltered.
COMPRESSOR INTERCONNECTION:
The sidechain sockets for interconnection of several compressors are located on the
rear panel.
A switch (LINK 1, LINK 2) on the front se lects which compressors are interconnected,
and on which bus they are connect ed. If you select LINK 1 on both channels, t hey will
perform exact t he same gainreduction.
Having several connected co mpressors in a rack, you can select which compressors
you will have working together.
By select ing e.g. LCA 2B no 1, ch. 1 on link 1, LCA 2B no 2, ch. 2 on link 1 and LCA
2B no 3, ch. 1 on link 1, they are now interconnected and all three will perform the
exact same compression.
The interconnection implies, that the unit, which performs the most compression , is
controll ing the others.
To cho ose 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.
(150205)
LYDKRAFT ApS
Mose Allé 20, DK-2610 Rø dovre
Denmark
2
CONTROLS:
GAIN:
DISPLAY:
LINK SWITCH:
IN/BYPASS:
COMPRESSOR:
The
control is used to "adjust" for the gain l oss, which takes
gain
place when the unit is compressin g. It is placed between VCA and
output st age. The
-control is continuously variable from -6dB to
gain
+10dB.
The g reen LED display shows the gainreduction for both the
compressor and for the limiter. A red LED shows if the limiter is
active.
The d isplay is fro m the factory supplied in dot mode. This can be
altered to a bar by placing a strap on U6 (U106) from
pin 3 to pin 9
Interconnects several compressors on link 1 or link 2.
If the compressor is left in the off p osition, it works entirely
independently.
This switch switches the compressor in and out of the signal path.
In the bypass po sition the entire u nit is switch out.
RATIO:
The
control varies the ratio by which the input signal is
ratio
compressed.
If the ratio selected is to 2:1, and the input signal increases 10dB,
the output signal is only increased by 5dB. The
ratio
control is
continuously variable from 1,6:1 to 20:1.
THRESHOLD:
The threshold is the point where the compressor begins its
action. It is defined as the point where the gain is red uced
by 1dB.
The threshold is related to the output le vel and is continuously
variable from off to -10dBU.
NOTE: If both the RATIO control and the T HRESHOLD control are at
their extreme (> 15:1 and < -5dB), overreaction can be
expected.
ATTACK:
The
attack
control chooses how fast/slow the compressor
responds to an increase in the input signal.
The a ttack control is continuously variable from 0.3 to 70
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 0,07 to 2
seconds.
(940530)
LYDKRAFT ApS
Mose Allé 20, DK-2610 Rø dovre
Denmark
3
ATTACK/RELEASE SELECT:
This switch selects how the compressor reacts to an increase
(
attack
) or decrease (
There are two settings of the switch:
1. Manual.
Attack ti me: from 0.3 mS to 10 mS
Release time: from 0.07 sec to 2 sec
2. Preset.
pos 1. 1,5 mS 0,25 S
pos 2. 1,5 mS 0,8 S
pos 3. 3mS 2,2 S
pos 4. 6mS 5,0 S
pos 5. 3mS 0,5/4 S
pos 6. 1,5 mS 0,5/4/20 S
release
) of the input signal.
Attack Release
The release time in position 5 and 6 is program dependent, that is:
pos 5, 6 for sho rt peaks: 0,5 S
pos 5, 6 for long peaks: 4S
pos 6 for continuously high levels: 20 S
LIMITER:
ON/OFF
THRESHOLD:
This switch defeats the limiter when in the
The threshold is related to the output le vel and is continuously
variable from off to 0dBU.
Ratio: 20:1
Attack: 0,6 mS
Release: 0,5 S
off
position
(940530)
LYDKRAFT ApS
Mose Allé 20, DK-2610 Rø dovre
Denmark
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