Crane Song STC-8 - Manual (Page 13)

PAGE 11
COMBINED COMPRESSOR-LIMITER
When the limiter is set to operate with the compressor, the green peak LED will light when the
limiter takes control. It is recommended that the limiter be used in conjuction with the compressor.
THE ATTACK MODULATION DECISION
Attack modulation (A-Mod) is in the upper right corner and lower left corner on the preset switch
(see Preset Switch layout, page 5). Using A-Mod will help prevent the chopped off limited type of
sound that occurs when a source is peak limited. A-Mod will usually result in a less processed
sound.
A-Mod is also useful in program averaging. When using long attack times a volume suck down
may occur at the beginning of a song because of the time it takes the compressor to bring gain
under control. The A-Mod setting shortens the compressor attack time when the peak threshold
is exceeded. Then it allows the compressor to return to normal operation. By having a shorter
attack time at the start of the song, the compressor quickly controls Gain, avoiding the volume
suck down.
Light to moderate peak limiting will result in transparent peak limiting when the limiter is used in
conjunction with the compressor.
"NUMBERS"
It is very difficult to assign numbers to Attack Time, Release Time, or Ratio. They change
continuously depending on the gain reductiion curve and amount of gain reduction taking place.
Ratio is defined as:
change in input dB
change in output dB
Ratio =
Amount of gain change can be determined by looking at Graph 1 and Graph 2 on page 7. As
evident in the diagrams, the ratio changes at different points on the graph. This change is deter-
mined by the amount of gain reduction taking place. The Shape Control changes the gain reduc-
tion curve (the shape of the knee). The limiter can also alter that curve. Its like having a second
threshold and knee. As a result of this flexibility there are no fixed numbers.
An important point to remember is that as more gain reduction takes place, the ratio becomes
higher. The ratio becomes higher when the need to control the sound source becomes greater.
By increasing the amount of gain reduction, the louder sound source will automatically cause more
gain reduction.
To increase the ratio, i.e. get tighter control, increase the amount of gain reduction taking place. In
the variable mode, one can also turn up the shape control . Most tube and optical based compres-
sors work like this.
Don't be afraid to make the STC-8 work. It is happy with 12 dB of gain reduction. Experiment, turn
the knobs, find sounds that you like. Numbers are meaningless if the sound is pleasing.