Rupert Neve Portico 5043 - Compressor / Limiter Duo - Manual (Page 9)

FEATURES
8
THRESHOLD
THRESHOLD control covers the range from below -30dB to +22dBu.
When THRESHOLD is set at a low level with a fairly high RATIO, the amount of gain reduction
will be considerable and it may be necessary to use some GAIN after the compressor to restore the
apparent signal level.
RELEASE (or RECOVERY) and ATTACK TIME
Range of RELEASE time is 100 mS to 2.5 Seconds.
Range of ATTACK time is 20 mS to 75 mS.
The notes above explain how the 5043 handles signals of constant amplitude such as pure tones.
Real program signals, however, are continually changing in level. The way in which a compressor
deals with actual program material depends upon the magnitude and duration of peaks in the
program level.
If the RELEASE TIME is set to be very short, a short duration signal will be compressed but the
gain will return to normal very quickly, giving a fluctuating and un-natural sound known as
"Pumping" when the background, or other signals, are forced up and down. The gain will also tend
to follow the wave form of low frequency signals. RELEASE TIME should be set long enough
for the gain to remain reasonably constant between each bass note or between speech syllables.
The ATTACK time is the time taken for the compression circuits to start compressing. A long
ATTACK time allows short duration peaks to "escape" and go through uncompressed. This may
cause overload on subsequent digital circuits. A very short attack time sounds un-natural and robs
the signal of "life" by removing transients. Some transients are extremely fast and have little effect
on the sound quality. Setting a long attack time often means that almost no gain reduction occurs
because the transient is history (!) before compression has had time to operate.
However, even the fastest circuits take time to operate which means that there is always some
"Overshoot". Small amounts of "Overshoot" are musically desirable - there are exceptions, of
course.
Setting the right values of RELEASE and ATTACK is what compression is all about! Once the
principles are understood a Compressor-Limiter such as the 5043 provides a powerful tool that
actually appears to enhance the dynamic range of a recording and so provide greater musical
enjoyment.
GAIN
GAIN range provided is from -6dB to +20 dB.
As already noted, when compression has taken place, it may be necessary to increase the overall
gain to restore the apparent program level
FB BUTTON
Switches from "Feed-Forward" compression mode to "Feed-Back" compression mode as described
earlier in this user guide.