Answer · Dynamics
What does glue compression on a bus do that compressing each track doesn't?
A bus compressor sits on the sum of several tracks. Its gain follows the combined signal and is applied to every track at once, so when the kick hits, the whole group dips together by a decibel or two. Compressors on separate tracks cannot do that, because each one hears only its own track.
Why it sounds glued
Instruments recorded separately have unrelated dynamics. A single compressor over all of them imposes one shared movement: every part breathes with the loudest element. The ear takes that common motion as a sign that the parts belong to one performance.
Settings
Glue is gentle. The aim is movement that is felt and not heard as compression.
| Control | Setting | Why |
|---|---|---|
| Ratio | 2:1, up to 4:1 | A low ratio moves the whole signal slightly instead of clamping peaks |
| Attack | 10 to 30 ms | Slow enough to let transients through |
| Release | 100 to 300 ms | Back to rest before the next beat |
| Gain reduction | 1 to 3 dB on the loudest hits | More than that and the bus pumps |
What it is not for
A bus compressor is the wrong tool for one instrument that is too loud or too uneven. It would turn the whole group down every time that instrument peaks. Control individual tracks with their own compressors first, then add glue across the bus.
Where to use it
The drum bus is the usual first place, then a group of backing vocals, a stack of guitars, and the master, where 1 to 2 dB is plenty.
In Zammoth
Select the tracks and press ⌘G. They get a bus with its own fader and device chain. Add a Compressor to the bus: its defaults, a 2:1 ratio with a 10 ms attack and a 120 ms release, are already in glue territory, so the threshold is the control to set. The bus's gain reduction shows in its mixer strip. Or ask:
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