Trap doubles hi-hats to fast rolls over a half-time-feel at ~140 BPM; boom-bap runs ~85–95 BPM with human swing

Hip-hop spans two dominant rhythmic sub-styles with contrasting tempos and drum approaches. Boom-bap (classic 80s–90s hip-hop) operates at ~85–95 BPM with heavy swing and ghost notes; the groove is laid-back and human. Trap (post-2010s) runs at ~140 BPM but uses a half-time-feel so the snare (or 808) lands on beat 3, making the body feel ~70 BPM while the fast hat rolls (ratchet-retrigger) create hyper-dense subdivision energy. Both share the sub-bass and sample-chop foundations but differ radically in tempo, swing, and hat density. Misapplying boom-bap swing to trap or trap hat rolls to boom-bap produces genre-incoherent results.

Examples

Boom-bap at cps 0.375 (~90 BPM), .swingBy(0.35,4), ghost notes on hats. Trap: cps 0.583 (~140 BPM), snare on 3 (half-time), s("hh*32").gain(0.3) for the fast hat grid.

Assessment

Given only tempo and snare placement, identify whether a beat is boom-bap or trap. Then describe what hat pattern and swing setting would be appropriate for each style.