9
UM TGMC-120117
BYPASS
SHARP
ATTACK
RELEASE
HOLD
ROUNDED
OUTPUT
IN
1
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5
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8
9
10
11
1
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11
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-10
-9
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-7
-6
-5
-4
-3
-2
-1
0
OPTO
KNEE
+ 1 2
+ 8
+ 4
0
+ 1 6
Gain
Reduction
TG1 OPTO
It is little known that EMI technical engineers experimented
with
opto
detection in their compression circuits. The
TG1
Opto
is an opto adaptation of Chandler Limited’s TG1 Lim-
iter, a recreation of the limiters found in the historic EMI
TG12345 recording consoles and TG12410 transfer desks of
the late ‘60s and ‘70s.
Historically referred to as a
level back-off system
, in a modern
context, the TG1 Opto compressor should be considered a
dynamic range reducer, that is- it attenuates transient peaks
while simultaneously amplifying quieter signals.
Important Notes on Use
A unique feature of this compressor is the inactive state gain
level - when at rest between compression cycles – as indi-
cated on the
Gain Reduction
meter when in bypass, can be
preset by means of the
Hold
control. An important benefit
of this moveable resting state is, a better signal/noise ratio
can be realized.
The key towards optimal employment of the TG1 Opto
compressor is, understanding the
Gain Reduction
meter and
Hold
control, without signal present.
The meter scale range begins below
0
and extends to
+20
at
the end of the red region.
The degree of compression available is relative to the posi-
tion of the meter needle from the top of the scale and cal-
culated as the difference thereof:
+20 - X needle position = Y
compression
.
For example, with the compressor in bypass, positioning the
meter needle by means of the
Hold
control to
+16
on the
scale, will provide up to +4 dB of compression.
Adjusting the
Hold
control anticlockwise, and placing the me-
ter needle at
0
on the scale will provide up to +20 dB of
available compression.
Note:
Placing the needle below meter
0
will allow maximum
possible reduction and set the inactive state gain to its high-
est level.
Tip:
Positioning of the needle between
+8
and
+12
on the
meter scale, can be a great starting point for most sources.
SHARP
ATTACK
HOLD
ROUNDED
1
2
3
4
5
6
7
8
9
10
11
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
OPTO
KNEE
+ 1 2
+ 8
+ 4
0
+ 1 6
Gain
Reduction
MOVEABLE
RESTING STATE
SHARP
ATTACK
HOLD
ROUNDED
1
2
3
4
5
6
7
8
9
10
11
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
OPTO
KNEE
+ 1 2
+ 8
+ 4
0
+ 1 6
Gain
Reduction
HOLD PLACED
AT METER 0
UP TO +20 dB
COMPRESSION
SHARP
ATTACK
HOLD
ROUNDED
1
2
3
4
5
6
7
8
9
10
11
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
OPTO
KNEE
+ 1 2
+ 8
+ 4
0
+ 1 6
Gain
Reduction
HOLD PLACED AT
METER +16
UP TO +4 dB
COMPRESSION
