It is very difficult to assign numbers to Attack Time, Release Time, or Ratio. They
change continuously depending on the gain reduction curve and amount of gain reduction
taking place. Ratio is defined as:
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 reduction 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 compressors 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.
The following chart is an attempt to show what happens with the A, B, and C Presets. For
the purpose of the measurements in the chart, the compression range is from no gain
reduction to 12 dB of gain reduction. Numbers in the chart are approximate. Ratio
conditions are as indicated.
Ratio conditions relate to the entire specific preset section, not to Release Time and
Conditions columns in the chart. i.e. Starting GR and Ratios in the A Preset section
relate to the whole section.