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Teletronix LA-2A Leveling Amplifier
Background
Audio professionals passionate about their compressors revere the LA-2A.
The original was immediately acknowledged for its natural compression char-
acteristics. A unique electro-optical attenuator system allows instantaneous
gain reduction with no increase in harmonic distortion – an accomplishment
at the time, still appreciated today.
The LA-2A is known for adding warmth (such as for vocals, guitar, or synths)
and fatness (such as for drums or bass) to signals.
LA-2A Signal
A functional block diagram of the LA-2A Leveling Amplifier is provided in
Flow
Figure
After this the signal is fed into both the side-chain circuit and the gain reduc-
tion circuit. The side-chain is comprised of a voltage amplifier, a pre-emphasis
filter, and a driver stage that provides the voltage necessary to drive the elec-
troluminescent panel. This signal controls the gain of the compressor. After the
gain reduction circuit, the signal is sent through an Output Gain control and
a two-stage output amplifier, followed by the output transformer.
Input
Figure 93. LA-2A signal flow
UAD Powered Plug-Ins Manual
93. The input transformer provides isolation and impedance matching.
Input
Transformer
Peak
Reduction
Voltage
Luminescent
Amplifier
Optical
Attenuator
Amplifier
Gain
Electro
Driver
Pre-
Stereo
Emphasis
Interconnection
Trim
- 284 -
Voltage
Cathode
Follower
Negative
Feedback
Output
Transformer
Chapter 25: LA-2A and 1176LN
Output
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