Kick FM

A two-operator FM kick — the punchy, aggressive drum behind gabber, hardcore, and a lot of modern techno. A carrier sine is bent by a second sine (the modulator) whose intensity slams in at the hit and vanishes almost instantly. That burst is the attack: a metallic, click-rich crack that dissolves into a clean, weighty sine body. Push it gently for a tight techno thump, crank it for a distorted hoover-kick that eats the whole low end.

How it works

The modulator's output is added to the carrier's phase (true phase modulation), so a fast FM envelope makes the tone start bright and dense, then collapse to a pure sine as the body rings out. Ratio sets the interval between the two operators — whole numbers stay musical and harmonic, in-between values turn clangy and metallic. A separate Punch envelope sweeps the pitch up at the very start for the classic kick "click," and Drive soft-clips the result into grit.

Controls

  • Level — base hit strength. This is the loudness knob; nothing needs to be

patched to get a full, strong kick.

  • Tune — the carrier's base frequency, 30–120 Hz. Around 45–55 Hz is fat

and sub-heavy; higher gets a tighter, tighter "tok."

  • Ratio — modulator-to-carrier frequency, 0.5–4×. 1 or 2 stay harmonic

and clean; non-integer values (1.4, 2.7) go metallic and gabber-ugly.

  • FM — how hard the modulator bends the carrier at the hit. Low is nearly a

pure sine; high is a bright, buzzy, distorted crack.

  • Decay — how long the body rings, 0.1–1 s. Short is a tight punch; long is

a booming, sustained kick.

  • Punch — a fast upward pitch sweep at onset. A little adds "tonk" and

attack; a lot gets aggressive and synthetic.

  • Drive — normalized soft-clip saturation. Low is nearly clean; cranked it

distorts into hard-techno / gabber territory. Level-matched, so it changes tone, not loudness.

Attenuverters

Each bends its CV input into a param: how much, and which polarity (negative = inverted). At 0 the matching input does nothing, so the knobs above rule.

  • Vel — Velocity/accent CV → Level.
  • FM — CV → FM amount (e.g. an envelope or LFO morphing the timbre).
  • Decay — CV → Decay (e.g. an envelope for evolving body length).

Inputs & outputs

  • Trig — a gate/trigger; each rising edge strikes the drum.
  • Vel — velocity/accent CV. Scaled by the Vel attenuverter and added to

Level (so unpatched, or with Vel at 0, the Level knob alone sets loudness).

  • Ptch — 1V/oct tuning of the carrier, added on top of the Tune knob.
  • FM CV / Decay CV — modulation inputs for FM amount and Decay, each scaled by

its attenuverter (±10 V = full range).

  • Out — the kick, at ±5 V.

Tips

  • For a clean techno kick, keep Ratio at 1 or 2, FM low-to-mid, and a

touch of Punch.

  • For gabber, set a non-integer Ratio, push FM and Drive, and shorten

Decay so the distortion bites the transient.

  • Patch a fast envelope into FM CV to sculpt the click independently of the

body — a longer FM tail turns the whole kick into a tom or a blead-y stab.