How to set up a drum bus

What is a drum bus?

Most drum parts arrive as several tracks: a kick, a snare, hats, maybe toms, percussion and a room recording. A drum bus is one more channel that all of those tracks are routed into before they reach the master. Each drum keeps its own fader and its own plug-ins, and then everything you put on the bus affects the whole kit together.

The word comes from mixing consoles, where a bus is a wire that carries several channels to the same place. In a DAW it's the same idea with a different name in each program. In Ableton Live you select the drum tracks and press Cmd+G (Ctrl+G on Windows) to put them in a group track. In Logic you select them and create a track stack, choosing Summing Stack. In Pro Tools you set each drum track's output to a bus and make an aux input track that listens to it. In FL Studio you route each drum's mixer insert to one insert and only that insert goes to the master.

However you make it, the bus is where the drums get processed as one instrument.

Why use a drum bus?

Control comes first. Once the kit is balanced, one fader turns the whole drum part up or down against the rest of the song, and one mute takes it out for a breakdown. Without a bus, you'd be riding eight faders at once.

Then there's glue. When a compressor sits on the bus, every loud hit turns the whole kit down a little, so the hats and the room duck with the snare and come back up together. The separate tracks start behaving like one drummer in one room. You'll hear engineers call that glue, and it's the main reason people put a compressor on a drum bus at all.

Level is the last reason. Drums have the tallest, shortest peaks in a mix, so they decide how loud the whole track can go before it hits 0 dBFS. Saturation and clipping on the bus lower those peaks against the average level. That lets you turn the drums up without making the master limiter work harder, and you can watch that happen in the lab: the stat marked Peak vs dry shows how far the bus peaks below the original at the same loudness.

Reading the lab

The four cards along the top are the chain, in the order the sound passes through them: EQ, glue compressor, saturation, clipper. Click a card, or press 1 to 4, to switch that processor on or off. Each card draws its own curve and shows one measured number, and the knobs that belong to a processor you've switched off are greyed out.

The big screen shows the whole loop. The pale shape is the drums as they arrive and the pink shape is what comes out of the chain. Under it, the amber lane is the compressor's gain reduction, and when the clipper is on a dashed line marks its ceiling. The screen below zooms in on one loud hit, so you can see how much of its front gets through before the compressor reacts.

The whole chain is matched to the loudness of the original, and A/B switches it off at that same loudness. Without that, the processed version would win every comparison just by being louder. The panel marked Right now describes what the chain is doing, using numbers measured from the loop, and it changes as you turn the knobs.

The loops come from Wonky Percussion, a Sounds Like You pack. You can also upload your own drum bounce, or press Record and play something for eight seconds, and it goes through the same chain. Nothing leaves your device.

The drum bus chain, in order

The order on this page is a common place to start, and each position has a reason. EQ comes first because it changes what the compressor reacts to. The compressor comes next so it works on clean, undistorted drums. Saturation follows, and the clipper goes last because its job is to catch whatever peaks are left. The effect order lesson covers the general rules behind this.

You won't always use all four: a lot of good drum buses are just an EQ and a compressor, and the other two earn a place when you can say what they're for.

Glue compression

Start with the compressor, since it does the most. On a bus, the job is small and regular: take 2 to 4 dB off the loudest hits and let go before the next one. A ratio of 2:1 to 4:1, an attack of 10 to 30 ms and a release of 100 to 300 ms is the usual starting point.

In the lab, step 2 sets a 4:1 ratio and a −15 dB threshold. The compressor takes up to 3.0 dB off the loudest hits, which is the middle of the usual range, and the amber lane returns to zero between them. Watch the close-up to see what the 30 ms attack does. The front of each hit, its transient, gets through before the gain comes down, so the hits stand out a little more against the rest of the kit: the crest factor goes up from 18.6 to 19.6 dB. So a bus compressor with a slow attack makes the drums a little punchier.

The release decides how the bus moves with the groove. Set it so the gain recovers just before the next beat. Stretch it to 600 ms, as step 3 does, and the compressor never fully lets go: on this loop the amber lane stays below −1.3 dB the whole time, and the kit swells up between the hits. That's pumping. In dance music people sometimes want exactly that; on a live-sounding kit it usually sounds like a mistake.

Plenty of plug-ins copy the bus compressor SSL built into its consoles in the 1980s. It has ratios of 2, 4 and 10:1, attacks from 0.1 to 30 ms and releases from 0.1 to 1.2 seconds plus an auto setting, and a 4:1 ratio with a 30 ms attack and the release on auto is a common place to start. Ableton's Glue Compressor is modelled on the same kind of console compressor. The bus compression lesson goes further into the controls.

EQ before the compressor

Drum bus EQ is broad. Narrow fixes belong on the individual drums, where you can cut a ringing snare without touching the hats. On the bus you're adjusting the whole kit's tone: a little weight at the bottom, a little air at the top, sometimes a gentle dip around 300 to 500 Hz if the kit sounds boxy, and often a high-pass around 30 Hz to take out rumble nobody can hear on small speakers.

Where the EQ sits changes what the compressor does. Step 4 adds 3 dB at 100 Hz with a shelf, and 2 dB above 8 kHz. Because the EQ comes first, the louder kick pushes the compressor harder, and it now takes 3.2 dB off the loudest hits instead of 3.0 dB. Cut the low end instead and the compressor eases off. The difference is small on this loop, and it grows the more of the kit's level sits in the low end.

If you want to shape the tone without changing the compression, put the EQ after the compressor. Plenty of engineers use one EQ on each side: cuts before, so the compressor isn't reacting to problems, and boosts after. The EQ before or after compression lesson covers that choice.

Saturation

Saturation bends the shape of the wave. Small signals pass through almost untouched and big ones get rounded off, the way tape and valve circuits behave when you push them. On drums it adds harmonics, which makes the kit sound thicker and brings the kick and snare forward on small speakers, and it rounds the tips of the loudest hits, which lowers the peaks against the average.

In step 5, 9 dB of drive takes the crest factor from 19.3 to 16.8 dB. Matched in loudness to the original, the bus now peaks 1.8 dB lower than the drums did when they arrived at it, so the saturator has bought you headroom as well as tone.

Ableton Live's Saturator, FabFilter Saturn 2 and Soundtoys Decapitator are all common choices here, and many tape plug-ins do the same job. Start with the drive low and turn it up until you hear the kit get thicker, then back off a little. The saturation lesson explains the curves in more detail.

Clipper

A clipper cuts off any part of the wave that goes over its ceiling. That sounds brutal, but drum peaks are so short that a few decibels of clipping is hard to hear. In step 6 the clipper cuts 3 dB off the loudest hit, and only 0.36% of the samples in the loop go over its ceiling. They're all on the tips of the biggest hits.

The payoff is level. With the whole chain on and the loudness matched, the bus now peaks 4.7 dB lower than the original, and the crest factor has gone from 18.6 dB at the start to 13.8 dB. That's room you can use to turn the drums up in the mix, or room the master limiter no longer has to find.

In the lab, the Push knob is the gain going into the clipper, counted from the point where the loudest peak just touches the ceiling, so 3 dB of Push shaves 3 dB off the loudest hit. In your DAW the clipper's input gain does the same job, and you watch its meter to see how much it's taking off. Kazrog KClip and FL Studio's Fruity Soft Clipper are two common clippers, and the soft clipping vs hard clipping vs limiting comparison shows how a clipper differs from a limiter.

Parallel compression on the drum bus

Parallel compression is the other common way to compress drums. Instead of a gentle compressor on the whole kit, you squash a copy hard and blend it under the untouched drums. The dry hits keep their front and the compressed copy lifts everything between them: the ghost notes, the room, the tail of the snare.

Step 7 sets the compressor to a 10:1 ratio, a 1 ms attack and a −32 dB threshold. On its own that takes up to 25.6 dB off the loop and sounds flattened. With the Mix knob at 35%, you hear 65% untouched drums and 35% squashed copy, and the kit gets denser without losing its snap.

If your compressor has no mix knob, make a second bus. Send the drum bus to it, put the heavy compressor there and bring its fader up under the original. The parallel compression lesson covers both ways and how to keep them in time with each other.

You can run glue and parallel together, with the glue compressor on the drum bus and a parallel bus fed from it, but start with one. They both thicken the kit, and two of them at once makes it easy to overdo.

How to set up a drum bus, step by step

This is the order the lab's lesson follows, and it works in any DAW.

1. Balance the kit firstGet the faders of the individual drums where you want them before you add anything to the bus. A bus compressor reacts to the balance you give it, so a snare that's too loud will drive it harder than everything else.
2. Route every drum to the busGroup the tracks, or set their outputs to one bus, and check that nothing still goes straight to the master as well. A drum that reaches the master twice gets louder, and can sound phasey once the bus is processed.
3. Leave headroomAim for the bus to peak somewhere around −6 dBFS before any processing. Saturation and clipping react to level, so the same settings sound different if the bus arrives hotter or quieter.
4. Put a compressor on itStart at 4:1 with a 30 ms attack and a 150 ms release, then lower the threshold until the loudest hits show 2 to 4 dB of gain reduction. Shorten the release if the meter doesn't get back to zero between hits.
5. Shape the tone with EQBroad moves only. Decide whether each move should change the compression (put it before) or leave it alone (put it after).
6. Saturate if the kit sounds thinTurn the drive up until the kit thickens, then back off a little.
7. Clip if the drums need levelPush it until it takes 1 to 3 dB off the loudest hits, and listen for crunch on the snare. Back off when you hear it.
8. Match the level and compareTurn the bus output down until the processed drums are as loud as the bypassed ones, then switch the chain off and on. If you can't say what got better, take something out.

Starting settings for a drum bus

These are where the lab's lesson begins, and they're reasonable starting points on most drum loops. The right end point depends on the drums and the song.

The kick and the bus compressor

The kick usually has the most energy in a kit, so it does most of the work of pushing the bus compressor. That's often what you want: the kit ducks a little on every kick and the groove locks together. When it goes too far, the hats and cymbals drop on each kick and swell back up, and the kit sounds like it's breathing.

The fix is to stop the compressor hearing so much of the kick. Many compressors can filter the signal they listen to, called the sidechain, so the compressor still processes the whole kit but responds less to the low end. FabFilter Pro-C 2 has a sidechain EQ for this, and Ableton's compressors have the same option in their sidechain section. A high-pass at 80 to 150 Hz in the sidechain is a common setting.

The other fix is routing. Some engineers send the kick straight to the mix bus and keep the rest of the kit on the drum bus, especially when an 808 or a sub-heavy kick needs to stay clean. Clipping a long, low note is a different matter from clipping a 2 ms snare transient, because the clipper flattens the whole note and turns it into a buzz. The kick and bass lesson covers how the two fit together.

Gain staging into the bus

You set a compressor's threshold against the level it's getting, so once it's set you can see from the meter how hard it's working. A saturator has no threshold: how much it distorts depends on how loud the signal is when it reaches it, so feed it 6 dB more and it distorts more with the same knob settings. A clipper works the same way against its ceiling: once the loudest peaks reach it, every extra decibel going in is a decibel shaved off them.

That's why the lab sets the level going into its clipper for you, and why you need to do it yourself in a DAW. Get the bus peaking at a sensible level first, around −6 dBFS, and use each plug-in's input gain to decide how hard it's driven. If you change the balance of the kit later, check the saturation and the clipper again. The gain staging lesson and the headroom lesson explain the levels in more detail.

All-in-one drum bus plug-ins

Some plug-ins put a whole drum bus chain in one window. Ableton Live has a device called Drum Buss with a compressor switch, drive with three distortion types, a transient control and a low-end resonator called Boom. Plug-ins like these are quick to use and a good way to hear what each stage does. The one thing they hide is the order, which is fixed inside the device, so when you want EQ between the compressor and the saturator, or a clipper at the very end, separate plug-ins give you that choice.

Common drum bus mistakes

Making every processor work hard

Each stage on the bus sounds best when it's doing a little. Ten decibels of gain reduction, heavy saturation and a clipper taking 6 dB off the peaks each leave an audible mark, and together they flatten the kit. In the lab, the whole chain lowers the peaks by 4.7 dB at the same loudness while the compressor only ever takes 3.2 dB and the clipper 3 dB.

Judging it louder

Saturation and clipping make the bus louder at the same peak level, and louder always sounds better at first. Turn the bus output down until it matches the bypassed version before you decide anything. The lab does this for you; your DAW won't.

Processing drums that were already processed

A lot of drum samples and loops, including most in sample packs, were compressed and saturated when they were made. Another heavy chain on top can push them past the point where they sound good. If a loop already sounds finished, a little glue compression may be all the bus needs. The compression lesson covers when to leave a sound alone.

Forgetting the room mics and the reverb

A compressor on the bus raises everything quiet between the hits, and room mics and reverb returns are exactly that. If the room suddenly sounds huge once the bus compressor goes on, pull the room fader down or route the reverb return around the bus.

Never comparing

Bypass the whole bus at matched level every few minutes. After half an hour of tweaking, your ears get used to almost anything, and switching back to the untouched drums is how you find out whether the bus is still helping.

Training your ears for the drum bus

The quiz under the lab plays the loop through one processor at a time, set harder than you would on a real bus, with the screens covered and the loudness matched. Your job is to say whether it's the compressor, the saturation or the clipper. The compressor shows up between the hits, as the kit dipping and swelling. Saturation shows up in the tone of everything, hats included. The clipper is the hardest: listen for a slight crunch right at the front of the loudest hits.

Questions people ask

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