SETUP MODE
The compressor and expander have almost identical controls. These are: BAND THRESHOLD Selects the frequency band. Sets the level at which the processors have an effect. The results are different for the compressor and the expander. For the compressor, the threshold sets the level at which compression takes place. Signals above the threshold will be compressed but signals below this level pass through the compressor unaffected. For the expander, the logic is the other way round - signals above the threshold are not affected but signals below the threshold are brought up in level according to the settings of the controls below. By using the two together, it is possible to create a 'compander' - i.e. signals above the threshold are reduced in level (compressor) and signals below the threshold are brought up in level (expander) as this simple example demonstrates:
The incoming signal level has a huge dynamic range going from very loud to very quiet. By setting the compressor and expander thresholds to the same value, the output of the processor will be the signal shown with the dashed line - as you can see, its dynamic range is now much more even. However, because the loud signal is now reduced in level quite dramatically, the overall signal level can be pushed up (shown with the otted line). This gives the effect of the whole thing sounding a lot 'louder' or 'bigger' and the fact that you can control each frequency band separately gives you a great deal of control. However, because you have completely separate control of the compressor and the expander's threshold, it is possible to set the processor so that loud signals are compressed and quiet signals are expanded as above but it is possible to leave a portion of the signal unaffected by either compression or expansion:
In this example, the portion of signal between the compressor's threshold and the expander's is unaffected.
