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This alarm is located in the lower, left-hand corner of the screen and
indicated by the arrow here. This alarm is shared with the input-
overload-sensing circuit, which is discussed at the top of Page 14.
This alarm has no associated tally output.
Limit and
Compress
Compression of program dynamics is available only as an extended
feature of the peak limiter, as explained earlier under the discussion
of the compression platform. Compression is not available as an
independent function.
When compression is enabled, the level of the signal applied to the
limiter section is increased by a static 6dB. At the same time, this
added gain is subtracted-out by forcing the compression platform to
a 6dB resting point.
Compression is gated, the same as the AGC, and in the illustration
above the gate is closed. Compression will seek its 6dB resting
value just as the AGC seeks 0dB.
As the input program signal has been given additional static gain,
the comparative loudness of the program material will increase cor-
respondingly. The limiter will continue to work quickly on program
peaks, but the compressor will act more on the average level of the
signal. The combination of all three processing functions ensures a
certain consistency to the audio program.
This illustration shows how the 261 might appear in operation as a
general-purpose leveler for loudness normalization.
