Vocal Bus Compression: 1 dB That Glues Every Layer
Vocal mixing · 4 min read
Route the lead, doubles, harmonies and adlibs to one vocal bus and compress it gently: ratio 2:1, attack around 30 ms, auto release, and no more than 1–2 dB of gain reduction in the loudest chorus. Then make sure the reverb and delay sends come off that bus after the compressor, so the space follows the glue instead of fighting it.
Gain reduction
1–2 dB
Ratio 2:1 · attack 30 ms · auto release
The 60-second answer
Ratio 2:1 (or 1.5:1), attack 30 ms, release auto or 300 ms, threshold set so the verses read close to zero and the loudest chorus reads 1–2 dB. High-pass the detector at 100 Hz. Put the bus reverb and delay sends after the compressor. If it pumps, lengthen the release before you lower the ratio.
Why a bus compressor glues and a channel compressor does not
On individual channels each compressor reacts to its own track. The lead ducks when the lead is loud, the double ducks when the double is loud, and the four tracks keep drifting relative to each other. On the bus, one detector sees the sum: when the adlib comes in, the whole stack moves down together by the same fraction of a decibel and comes back together. That shared movement is what the ear reads as one source rather than several, which is why 1 dB is enough.
Why the attack has to be slow here
A fast attack on a bus compressor clamps the front of every consonant in every layer at once, and because the detector is seeing four tracks of consonants, the clamping happens constantly. The result is a stack that sounds dense and unintelligible at the same time. At 30 ms the compressor lets the whole consonant through and only responds to the sustained energy behind it, which is the part that needs holding together. Slow attack plus auto release on a bus is close to a rule.
Setting up the vocal bus, step by step
| # | Do this |
|---|---|
| 01 |
Route only vocals to the bus Lead, doubles, harmonies, adlibs. Not the beat, not a vocal sample, not the 808. One bus, one source family. |
| 02 |
Balance the layers first Get the doubles and adlibs sitting where you want them before any bus processing. The compressor should not be doing the balancing. |
| 03 |
Ratio 2:1, attack 30 ms, auto release The starting point for almost every vocal stack. Auto release lets recovery track the phrasing instead of a fixed number. Ratio 2:1, attack 30 ms |
| 04 |
Threshold for 1–2 dB in the chorus only Play the busiest section. Verses should show close to zero. If the verse is doing 2 dB, you set it too low. GR: 1–2 dB max |
| 05 |
High-pass the sidechain detector at 100 Hz Plosives and chest energy from four layers trigger the compressor for the wrong reasons. Filter the detector, not the audio. Detector HPF 100 Hz |
| 06 |
Send the space from after the compressor Post-insert sends from the bus, not pre. Then A/B level-matched and nudge the double fader again if the balance shifted. Sends: post-insert |
The trick: put the bus compressor before the reverb send, not after
This is a routing decision, it takes five seconds, and it changes more than any setting on the plugin. If your reverb and delay sends come off the vocals before the bus compressor, the reverb hears the uncompressed stack. So in the loudest chorus the dry vocal is held down 2 dB while the reverb gets the full 2 dB louder — the mix goes wetter at the moment you needed it driest, and the stack smears behind the beat. Flip it. Feed the sends from after the bus compressor and the reverb level tracks the compressed dry level, so the wet-to-dry ratio stays constant from the first verse to the last chorus. The stack then reads as one voice in one room instead of four voices in four rooms. Check it by soloing the reverb return through a chorus: its meter should be almost as steady as the dry bus.
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- 4–6 dB of gain reduction on the bus. That is not glue, it is a second round of channel compression. The stack goes flat and the lead disappears into it.
- Fast attack. Under about 10 ms on a bus you clamp four layers of consonants at once and the stack turns to mush.
- Sending anything but vocals to the bus. One kick in the detector and the whole stack ducks on every beat.
- Setting it before the layers are balanced. The compressor reacts to the sum, so every fader move afterwards changes what it is doing.
One decibel is a strange thing to fight for, but it is the step that turns a pile of tracks into a single voice. Set it, leave it, and spend the rest of your time on the lead.
Keep going
FAQ
How much gain reduction should a vocal bus compressor do?
1–2 dB in the loudest section and close to zero in the verses. If it is working through the whole song, raise the threshold.
What ratio for vocal bus compression?
2:1 is the standard starting point, or 1.5:1 if the channels are already heavily compressed. Above 4:1 you are no longer gluing.
Should the reverb send come before or after the bus compressor?
After. Then the reverb level follows the compressed dry level and the wet-to-dry balance stays constant through the song.
Who's behind this
Ivan Meshcheriakov · IvanFromRnD
5+ years ago I moved to LA with zero connections and started building from nothing — 14-hour days, meeting people and interning at studios. It took me 5+ years to meet and interview 100+ Grammy-winning engineers — then I turned it all into the Vocal Chain Bible.
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