Stereo and Mono Sidechain Compressors for Tracktion

Working the Knobs

Lowering the threshold while keeping the compression ratio fixed reduces the maximum output level, since you’re compressing over a larger portion of the dynamic range of the input signal. By keeping the threshold fixed but increasing the compression ratio, you’ll reduce the output level by compressing only the loudest signals. There are no rules for this. Let your ears be your guide, with the meters as a sanity check.

As an exercise, try plotting out a few combinations yourself. Then set up your compressor and listen to the differences.

The Compressor as a Tone Modifier

Adjusting the attack and release times of a compressor applied to an instrument can change its timbre by rounding off a sharp attack or stretching out the sustain portion of the note’s envelope. It’s sort of like having an equalizer with a different parameter.

A drum hit can be “stretched out” by applying a long release time, a healthy gain boost, and fairly high compression ratio.

Compressing low-frequency program material requires special care. The attack and decay portions of a kick drum are 60 to 80 milliseconds long, but a low-pitched kick has a fundamental frequency of about 40 Hz. This means that only three of four cycles of the kick’s fundamental frequency are heard on each hit, much of that being in the decay portion of the envelope.

Compressing the drum with a fast attack time and high compression ratio will make more cycles of the attack portion of the drum audible, making its “thump” sound much more pronounced without having to boost low frequency gain with an equalizer. Try this next time you want a kick in the chest.

compressed, often allowing you to increase the impact of the kick drum without increasing the level of the track in the mix.

Compressors with very fast attack time that often work well on vocals, work poorly on a bass because the compressor actually tries to follow the individual cycles of the waveform rather than the envelope of the note. This characteristic can be used as a special effect, but usually it just takes all the life out of a bassy instrument.

Some people put a hardware compressor inline with a signal, with the controls set for no compression action at all. One reason is that they like what the electronics of the input and output amplifiers do to the sound. This is most noticeable with “vintage” units that use tube electronics – a mighty expensive tube-in-a-box, but if it’s there and it works, there’s no reason not to use it.

The Bottom Line

A compressor can never be used by the book

–not even this one. You need to listen carefully when you make adjustments. By understanding the effect of each of the adjustable parameters, you’ll be better able to reach your goal quickly.

The beater attack is at a higher frequency

(1 to 3 kHz) so a moderately fast attack will let a few cycles of beater through while working on the low “whump.” Slowing down the attack lets more of the beater sound pass before being

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User’s Guide

 

Answers

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