How to Use an Audio Compressor

A drum can have a loud peak and still feel small. A bass can look fairly even on the meter and keep disappearing between notes. Before reaching for a compressor, pick the part you want to change: the first hit, the body of the note, or the difference between one phrase and the next. They are not quite the same job.

The devices below are the Compressor from the TuttiDAW editor, running on the audio shown above them. Press Play, change a control, and listen. Starting another example pauses the previous one without losing its position or settings. Nothing plays automatically.

Attack: leave some of the hit alone

Play the drum pattern. The threshold is deliberately low enough that you can hear the compressor working. Listen to the beginning of each hit before changing anything.

Take Attack down from 20 ms toward 1 ms. The front of the hit should become less prominent. Bring it back up and listen for that small, sharp part returning ahead of the body. A slower attack is not adding a transient: it is allowing more of the original one through before the gain reduction develops.

Neither position is automatically better. A snare that is already poking out may need its front edge softened. One that gets lost behind guitars may need that edge left intact. Make the decision with the other instruments playing, not just with the drum soloed.

Attack is a response time, not a delay before the compressor notices the signal. Gain reduction develops over time; it does not wait exactly 20 ms and then switch on. The detector and envelope shape also matter, so the same number on a different compressor need not produce the same transient.

Release: listen to what happens after the loud note

This bass phrase has a louder accent followed by quieter notes. Leave Attack alone for a moment. With Release at 400 ms, watch the gain-reduction display and listen to the note after the accent.

Shorten Release toward 80 ms. The gain has more time to recover before the following note. Lengthen it toward 800 ms and notice whether the quieter notes seem held back. If the whole phrase feels smaller than you intended, raising the output is not the only answer: the compressor may simply be staying down too long.

Very short release times can give a useful restless movement. On low notes they can also roughen the tone as gain changes begin to follow the waveform itself. If the bass sounds gritty when you wanted it steady, lengthen Release and compare again.

Both examples are original synthesized test phrases, not recordings of a drummer or bass player. Use your own audio in either example to check the same decisions against real performances. Replacing the audio keeps that example's compressor settings.

Threshold, ratio and makeup gain

Threshold sets the level around which compression begins. Ratio sets the slope above it. At 4:1, an input 8 dB above threshold settles around 2 dB above it, before output gain, once the envelope has settled and outside the knee. That arithmetic describes the steady-state curve, not the exact peak of a short drum hit.

Lower Threshold until the passages you want to control produce gain reduction. There is no useful universal threshold for “a vocal”: the recording level changes where the signal meets it. Knee softens the transition around threshold; it does not replace Attack or Release.

Use Out to bring the processed level close to the bypassed level, then switch Bypass a few times. The examples do not automatically loudness-match the two signals. Louder often seems fuller at first, which can disguise a loss of movement or clarity.

Compressor settings for vocals, drums and bass

A vocal that moves in and out of the mix

If an entire line is too quiet, adjust clip gain or volume automation first. Then let compression catch the smaller changes within the performance. Start with a moderate ratio, around 2:1 to 3:1, and lower Threshold while listening to the words that jump forward. If consonants become dull, try a slower attack before adding high-frequency EQ.

A drum bus that needs to hold together

Try a slower attack and a release that recovers comfortably between strong hits. Watch whether the kick is driving the gain reduction for the entire kit. Some movement can feel good; a hi-hat that ducks every time the kick lands may be a clue that you are compressing more than this arrangement needs.

A bass with uneven notes

First check whether a few notes are louder or whether some frequencies simply carry better through the mix. Compression can control level, but it cannot make two notes occupy the same frequency range. Use the release example as a starting point, then check that quieter notes are not being pulled down by the accent before them.

Before moving on

Keep the setting if the part sits better at a comparable loudness. If it was already sitting well, leaving the compressor bypassed is a perfectly useful result. You do not owe every track a device.

Work with a file in the compressor tool or open the full studio to hear these decisions in a complete mix.