TL Audio VP-1 - Manual (Page 14)

the opposite direction, but our feeling is that as you turn the control ‘up’ it should
have more effect!
4.19 Compressor Attack and Release.
The attack time governs how quickly the compressor acts to ‘squash’ a signal that has
exceeded the Threshold, and is variable from 0.5msec to 50msec. At 0.5msec attack,
the compressor is fast enough to reduce the gain of a 1KHz signal in less than half a
cycle, effectively preventing an overload of any following equipment which has
limited headroom, such as a digital processor, tape machine or transmitter.
The release time sets how quickly the signal gain returns to normal once it has
crossed above the threshold again, and is variable from 40msec to approximately 4
seconds. Adjustment of the attack and release times allows unobtrusive compression
to be applied to virtually any audio signal, but should very short transients occur the
time constants become signal dependant, generally reduced, to prevent a slow release
leaving a “hole” in the signal after the transient. Also, a fast release setting will be
extended by a slow attack setting. Due to this automatic modification of the time
constants, the controls are simply calibrated “fast” to “slow”.
4.20 Compressor
Ratio.
The Ratio controls the degree to which signals over the threshold are compressed, and
is expressed as a ratio of the input and output signals. For instance, a ratio of 1:3
means that for every increase of 3dB in the input signal, a 1dB increase in output
level results. Higher ratios result in a more highly compressed sound.
The ratio may be varied from 1:1.5 (very gentle compression) to 1:30 (near limiting).
The compressor normally operates with a “soft-knee”, i.e. the compression is
gradually introduced as the signal passes the threshold, in which case the ratio refers
to the compression eventually obtained.
4.21 Compressor Gain Make-Up.
When a signal is compressed its gain is reduced, and the gain make-up control allows
up to 20dB of extra gain to be applied to bring the level of the compressed signal up
to that of the original. This retains the subjective loudness of the signal, and allows
easy A/B comparisons of the original and compressed signals without a change in
level occurring when switching between the two.
4.22 Compressor
Knee.