VC 160

The gain control lifts the gain level across the whole track. The quiet parts become louder and more present, and the peaks, which are now even louder, get taken care of later.

The threshold is the point where the compressor starts working. Any incoming signal louder than specified threshold gets compressed, making it quieter. How much quieter depends on the ratio. For example: if an incoming signal exceeds the threshold by 10 db, and you have a ratio of 10:1 (ten to one), the signal at the output will be 1 db higher than the threshold.

The attack time determines how fast the compressor starts working after the incoming level exceeds the threshold. Beware of overly short attack: this can shave off the transients,* creating a dull, lifeless sound. If the attack is too long, though, the compressor responds too late. Use your ears, not your eyes, to set attack time.

*Transients are non-harmonic material at the onset of the sound. They add character and brightness.

This is the time it takes the compressor to stop working after the incoming level has fallen below the threshold. It typically ranges from 20 ms up to a few seconds — the faster the release, the harder the compression. Overly short release times can result in undesirable 'breathing' or 'pumping' effects. Every source needs a different release time, so experimentation is required.

If you use a 'slow' compressor on very dynamic material, such as vocals with big peaks, it can lead to breathing or pumping effects. To avoid this, put a fast compressor, such as the VC 76, before the slow compressor in a chain. The faster compressor is there to reduce the big peaks, so set threshold and ratio high, with a relatively fast attack and release. Then the smoother compressor — with the threshold and ratio low, medium/slow attack and release — can operate better.

This is often used by radio DJs for reducing the volume of a track while they talk. The compressor is on the music, and a control signal — in this case the DJ's microphone — is assigned to the sidechain input. When the DJ starts talking, the signal triggers the compressor, which reduces the volume of the track — the music 'ducks' out of the way.

In music production, this function is often used to duck synth pads using the kickdrum for a characteristic 'pumping' sound, or to duck a bassline via the kickdrum to keep the bottom 'clean'. Put the compressor on the track to be ducked, assign the kick drum as control signal sidechain input.

This is useful for controlling specific problematic frequencies in an instrument, or for compressing a selected frequency range only.

Put the compressor in an insert on the track you want to compress, and send the signal from this track to an auxiliary bus. Insert an EQ effect on the auxiliary bus, then route the 'out' of auxiliary bus to the sidechain input on the compressor. Now adjust the EQ in the auxiliary bus until only the problematic frequencies are heard, and these frequencies will then trigger the compression.