A drum voice sets its oscillator to a fixed Hz rather than tracking MIDI pitch

Most synthesizer oscillators track the keyboard: a C3 produces one pitch, a C4 an octave higher. Drum synthesis breaks this convention by switching the oscillator to a fixed frequency (e.g., 70 Hz for a bass-drum fundamental). This decouples the drum timbre from note pitch, so any MIDI note on the drum rack triggers the same sound. The fixed frequency should approximate the real instrument’s fundamental: bass-drum membranes resonate around 60–100 Hz, a snare body higher (~140 Hz). After fixing frequency, the pitch-envelope sweep becomes the only frequency motion, giving full control over the initial transient. This is a general drum-synthesis step, applied to a plain sine before any FM is added.

Examples

In Ableton Operator: enable ‘Fixed’ frequency mode on oscillator A, set Hz to 70 for a kick or 140 for a snare fundamental. The drum now sounds the same regardless of which pad in the rack fires it.

Assessment

Explain why a drum voice that tracks MIDI pitch creates problems in a multi-pad drum rack. Then set up a sine oscillator at 70 Hz in fixed-frequency mode and verify by triggering two different pads.