busy bass = simple drums: balancing groove density in house

busy bass, simple drums. simple bass, busy drums. call it a rule of thumb rather than a law, because good records bend it all the time, but it's the fastest way out of a groove that feels either cluttered or dead. picture the bottom of your mix as a small dance floor. the kick and the bassline both want to dance on it, and when they both go wild at the same time they trip over each other. when neither of them moves, nobody dances at all. the magic is in the trade.

here's why it works. the kick and the bass both keep most of their weight in the deep end of the mix, roughly below 100Hz. in Sound On Sound, Mike Senior calls the clash between them "the most critical sub-100Hz conflict in modern mixes", because those two sounds usually make up the lion's share of your track's level. and down there your ears are bad at following detail: Paul White, also in Sound On Sound, points out that very low frequencies are "felt as much as they are heard". so when the kick and the bass both play lots of notes, the low end turns into one long blur. pick who moves. one part holds the floor steady, the other one dances on top.

what density actually means

density is simply how much is happening in a part: how many notes or hits land in each bar, and where they land. to see it, split one bar of 4/4 into 16 equal steps, called 16th notes. in house the kick usually sits on steps 1, 5, 9 and 13, the four beats you count as "one, two, three, four". the steps exactly halfway between those beats are the offbeats, the "and" when you count "one-and-two-and". a bassline that fills most of the 16 steps is busy. a bassline that plays one note on each offbeat is simple, even if that note is fat and loud.

count the dots in both versions. they spend roughly the same amount of movement, just on different instruments. that's the whole idea: your groove has a budget, and you decide who gets to spend it.

read your bassline first

before you touch a single drum, look at the bass. it tells you what the drums are allowed to do.

• simple bass: one note per offbeat. a short bass note on every "and" is one of the oldest moves in dance music. Senior describes separating the kick and the bass in time with "the simple off-beat" pattern as a time-honoured technique of the dance crowd. that bass leaves big gaps, and the gaps are an invitation: fill them with a 16th-note shaker, a hat pattern with ghost notes (very quiet hits tucked between the loud ones), a syncopated clap, or little percussion fills rolling between the kicks.
• busy bass: a rolling line. if your bass is a restless reese (the detuned, swirling bass we unpack in four machines, one low end) or a fast acid line crawling over all 16 steps, the bass is already doing the dancing. give it room: four-on-the-floor kick, one clean offbeat hat, a clap on beats two and four, and not much else. the drums turn into the metronome the bass rides on.
• somewhere in between. most real basslines sit in the middle. our quick test: count the notes in one bar. more than about eight and you treat it as busy. four or fewer and you treat it as simple.

the acid line is the classic busy bass. Roland released the TB-303 in 1981 to replace a bass guitar, and it flopped. cheap second-hand units then ended up as a foundation of acid house, Chicago house and techno, and Phuture's "Acid Tracks" from 1987 is often credited as the first acid house track. a 16th-note acid line can move on nearly every step, so the drums around it have to stay out of the way.

the one-bar test that never lies

loop a single bar and mute everything except the kick and the bass. that pair is the engine of your track. if they fight, meaning you can't hear where the kick lands or the bass swallows its punch, fix it here before you add a single hat.

• duck the bass under the kick. sidechain compression sounds scary, but the idea is simple: you put a compressor on the bass and let the kick control it, so every time the kick hits, the bass dips in level for a moment and then comes back. White says a dip of around 3dB "still sounds pretty natural", and Senior says you can rarely push past 2 to 3dB per hit before the bassline starts to sound odd. the attack (how quickly the dip starts) should be fast. the release (how quickly the bass comes back up) depends mostly on how long your kick rings and on your tempo, as Attack Magazine puts it. at 125bpm your kicks land 480 milliseconds apart, so the bass needs to be back up well before the next one.
• exaggerate, then back off. White's trick for finding that release: turn the ducking up until you hear far too much pumping, adjust the release until the pumping moves with the groove instead of against it, then pull the amount back to what you actually need.
• give the sub one owner. the same trade works in frequency. White notes that a deep, solid bassline often works better with a less deep kick, and a track driven by a solid kick often works better with a more constrained bass. "which way you roll on this is a purely artistic decision." Senior adds that nudging the kick sample's pitch "can save a good deal of EQ work".
• clean out the rumble. White suggests a low-cut filter (it removes everything below a set frequency) at around 30 to 40Hz on kick and bass recordings, because that ultra-low energy "does nothing useful or audible, but still eats up mix headroom". with synth basses, keep the cut below the lowest note you actually play, or you'll thin out the very notes you wanted.
• add the busy layer last. only now bring in hats, shakers and percussion, and only as much as the bass density allows.

accents count as density too

density isn't only the number of notes. it's also how loud each one is. in MIDI that loudness is called velocity, and Ableton's manual describes it plainly as a note's loudness, set by how hard you press the key or pad. a simple bass with hard accents can feel busier than a 16th-note line played dead flat, so treat velocity as a density control, not just the note count.

• roll the hats down on the kick, up in the gaps. a small drop in velocity on the hits that land with the kick, and a lift on the ones in between, makes a simple kit groove harder without adding a single hit. Attack Magazine's rolling deep house breakdown uses one lower-velocity hat hit to introduce "a subtle shuffle".
• never leave everything at full velocity. Roger Linn, who put swing and quantising into drum machines with his 1979 LM-1, told Attack Magazine that a drummer playing every hi-hat at exactly the same volume would "sound like a bad drum machine beat".
• accent the bass sparingly. if the bass is the busy part, accent two or three notes per bar and keep the rest softer, so the line has a shape instead of a wall.

the density flip: keep eight bars interesting

a loop that never changes gets old fast, and the fix doesn't need new sounds. flip the density halfway. bars 1 to 4: busy bass, simple drums. bars 5 to 8: drop the bassline to one held root note (the note the chord is named after) and let the drums open up with 16th-note shakers, rides and fills. same energy, spent on the other side of the floor. the contrast makes the second half feel like a lift even though nothing got louder, and it's the same logic that makes pulling everything back before a drop work so well.

pick drums that leave room

half of this battle is sample choice.

• kicks. Wikipedia sums up the two classic Roland drum machines neatly: the 808 is known for its "boomy" bass, while the 909 sounds aggressive and "punchy". against a busy, sub-heavy bass, a shorter and tighter kick leaves space. Senior's advice when the bass hogs the low end: your kick may need more energy than you'd expect around 100 to 200Hz instead of in the sub.
• hats and shakers. short sounds with a quick decay keep a busy top end clean. Attack Magazine's rolling deep house beat keeps its percussion "deliberately short, with no messy overlaps".
• loops. a drum loop without a kick (often called a top loop) is the quickest way to add busy drums over a simple bass, because it can't fight your kick.

common mistakes

• both parts busy. a rolling bass plus rolling percussion plus fills turns into mush, however good each part sounds on its own.
• both parts simple. an offbeat bass over a bare four-on-the-floor kit is a starting point, not a groove. something has to move.
• ducking to fix everything. sidechain helps the kick punch through, but it can't fix two parts that play in the same places. move notes first, then duck.

let the drums do their half

trading density back and forth is much easier when you have drums in both flavours ready to go. that's the idea behind 90sDrumz: 153 sounds built on 808, 909 and old-school drum machine samples, with every hit run through compression, EQ and saturation so it sits in a mix straight away.

• for a simple bass: 16 top loops, 16 percussion loops, 8 shaker loops and 8 ride loops to fill the gaps.
• for a busy bass: single hits (8 kicks, 9 snares, 8 claps, 16 hats) so you can program a lean kit that stays out of the way.
• for everything in between: 16 full drum loops and 8 breakbeats at 127 to 132 BPM, group-processed so they already sound like one kit.

all WAV, 24-bit / 44.1kHz and royalty-free. and if the bass side still feels crowded, stop layering every note of your bassline is the next read. press play. make a belter.

sources

• Mixing bass (Sound On Sound)
• Mix tips for kick & bass (Sound On Sound)
• Ten tips for better basslines (Attack Magazine)
• Beat Dissected: rolling deep house (Attack Magazine)
• Roger Linn on swing, groove & the magic of the MPC's timing (Attack Magazine)
• Editing MIDI (Ableton Reference Manual)
• Roland TB-303 (Wikipedia)
• Roland TR-909 (Wikipedia)