TL Audio VP-1 - Manual (Page 17)

but the EQ Pre switch will route the signal through the EQ first. This can result in a
different tonal character, and also allows certain frequencies to be boosted ahead of
the compressor, resulting in a certain degree of frequency conscious action by the
compressor itself.
4.32 Stereo Link Operation.
Two VP-1s may be configured for stereo operation by inserting a Link cable between
the two units and activating the Link switch on both units. In this mode, the control
voltages of the two compressor sections are linked, as are the two limiter sections,
ensuring that the same amount of gain reduction is applied to both channels (even if
one signal is below the threshold). This ensures that the stereo image is preserved. In
this mode there is no ‘master’ or ‘slave’ as such - the unit causing the most gain
reduction will dictate how much compression is applied to the other linked unit. All
the controls on the two units still remain independent.
4.33 Ducking or Gating.
A variation on stereo operation as described above is master-slave operation, where
the gain of one VP-1 is controlled from another unit, but without reciprocal action.
This is useful where a voice channel input is required to reduce the gain of, for
example, background music when the microphone signal is present.
The link cable should be fitted, as for stereo operation, but the Stereo Link switch
should only be depressed on the “slave” VP-1 (the background music channel in the
example above). If the compressor is switched out on the master unit, gain reduction
will only occur on the slave unit. The threshold and ratio controls on the master VP-1
will determine the extent of the gain reduction in the slave unit.
4.34 Peak Output Limiter.
The VP-1 output limiter is an optical design that provides responsive yet natural
control of output peaks - making it ideal for preventing overload in digital recorders.
Digital recorders will distort in a very unmusical way when overloaded to any degree,
so an output limiter is an ideal way of preventing over-modulation occurring. The
limiter is programmed with a very high ratio, short attack time and longer release
time, resulting in a fast response “brick wall” action.
A threshold control allows the limiter threshold to be varied between 0 and 20dB, and
a bypass switch with status LED is also provided. An red ‘active’ LED illuminates
when the limit threshold is crossed, and this is always connected - even when the
limiter itself is bypassed - making it useful as an output peak indicator.
The limiter is positioned post the output level control, so the user can be confident
that any increase in output gain will be precisely controlled.