# SC4

### From Audacity Manual

SC4 is a stereo compressor with a variable envelope follower for RMS / peak behaviour.

  Accessed by: Effect > SC4...

## RMS/peak

The balance between the RMS and peak envelope followers. The followers use the amplitude variation information in the waveform to affect the gain applied by the compressor. The RMS follower is generally better for subtle, musical compression and the peak follower is better for heavier, fast compression and percussion.

## Attack time (ms)

How soon the compressor starts to compress the dynamics after the threshold is exceeded, in milliseconds.

## Release time (ms)

How soon the compressor starts to release the volume level back to normal after the level drops below the threshold, in milliseconds.

## Threshold level (dB)

The level at which the compressor will start to apply.

## Ratio (1:n)

The gain reduction ratio used when the signal level exceeds the threshold level. Higher ratios reduce the gain more.

You must move this control from the default ratio of 1:1 for the effect to apply.

## Knee radius (dB)

The distance from the threshold where the knee curve starts.

## Makeup gain (dB)

The amount of gain added to the processed result.

## Links

|< Index of Effects, Generators and Analyzers

|< Effect Menu

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