Hip-Hop Drums: Boom Bap and Trap

Hip-hop drums split into two big families. Boom bap is the sampled, swung sound of 1990s New York, played at its real tempo of roughly 85–95 BPM. Trap came out of Atlanta in the 2000s and is written at 130–160 BPM but felt at half that speed. Both use the 16-step grid from the previous lesson.

Boom bap

The name describes it: the kick is the "boom", the snare is the "bap". The snare sits on beats 2 and 4, and the kick plays a syncopated figure around it.

Kick    x . . . . . . x . . x . . . . .
Snare   . . . . x . . . . . . . x . . .
Hat     x . x . x . x . x . x . x . x .

The kick on step 8 (just before beat 3) and step 11 is what gives boom bap its bounce. Try moving the second kick between steps 10, 11 and 12 and listen to how the feel changes.

What makes it sound like boom bap

• Swing. Boom bap almost always has swing on the 16ths, typically 58–62% on an MPC-style swing control. That is covered properly in velocity, swing and humanising.
• Sampled drums. Dusty, slightly compressed kicks and snares, often taken from old funk and soul breaks.
• Hats that breathe. 8th-note hats with uneven velocities rather than a machine-gun of identical hits.

Trap

Trap is written at a fast tempo, say 140 BPM, but the snare only lands once per bar, on beat 3 (step 9). That makes it feel like 70 BPM, which is called half time.

Kick/808 x . . . . . . . . . x . . . . .
Snare    . . . . . . . . x . . . . . . .
Hat      x . x . x . x . x . x . x . x .

The hats keep running at the fast tempo while the snare walks at half speed. That tension, quick hats over a slow pulse, is the trap sound.

Hi-hat rolls

Rolls replace one beat of the hat pattern with a faster subdivision. Each beat can hold:

Roll	Notes per beat	Feel
1/16	4	Standard
1/16 triplet	6	Skippy, rolling
1/32	8	Fast stutter
1/32 triplet	12	Buzz
1/64	16	Near-tone, use briefly

Good rolls are short and placed, usually at the end of a bar or leading into the snare, and they often ramp velocity up or down. Pitching the last few hits of a roll up a few semitones is another common move. A roll on every beat stops being an accent and becomes noise.

Writing the 808

In trap the kick and bass are often the same sound: an 808, a sine-like tone with a long tail. You program it as a melody, on the notes of the track's key.

• Keep it monophonic. Each new 808 note should cut off the previous one, or two long tails will clash and phase.
• Leave space around the snare. Many producers avoid an 808 hit right on step 9 so the snare speaks clearly.
• Use glides sparingly. A pitch slide from one 808 note to the next (portamento) is a signature move. Use it as a lead-in to a new phrase, not on every note.
• Stay low. Most 808 notes sit between roughly 30 and 60 Hz (B0 to B1). Notes much higher than that start to sound like a separate bass synth.

Find the song's key first with the key and BPM finder if you are writing to a sample, then write the 808 line on the root and fifth before adding passing notes.

Drill, briefly

UK and New York drill are trap's close relatives at 138–145 BPM, with a two-bar snare figure: the snare on step 9 in the first bar and on step 13 in the second. That late second snare creates drill's distinctive lurch. Hats tend to be 8ths with gaps and short triplet bursts, and 808s slide more often.

Common mistakes

• Programming trap at 70 BPM. You lose the resolution for fast hats; write at double time.
• Swinging trap hats heavily. Trap is mostly straight; the bounce comes from rolls and triplets.
• Letting the 808 and kick both hit hard on the same step without checking how they sum. More on this in the layering and tuning lesson.