CV Input Signal Types #7 — Velocity and Accent
| Property | Value |
|---|---|
| Category | Unipolar / Modulation |
| Voltage Range | 0..+5V (typ.), some modules up to +8V |
| Polarity | Unipolar |
| Bandwidth | Stepped / DC |
Description
Velocity CV represents the strike intensity of a note. Accent is a simplified variant — a binary or graduated "louder/softer" signal, often implemented as a trigger with variable voltage.
Velocity changes only at note-on — between notes, the value remains constant (stepped). This distinguishes velocity from continuous modulation signals like pressure.
Use Cases
- Volume variation per note (VCA modulation)
- Filter opening dependent on strike intensity
- Vary decay time (harder strike = longer decay)
- Accent patterns in drum sequences (e.g., 303-style accent)
- Control glide/portamento time (303-style: accent affects slide behavior)
Eurorack Examples (Mutable Instruments)
- Marbles: External CV shifts probability distributions (bias)
- Plaits: LEVEL usable as velocity substitute
Hardware Implementation
Input Stage: OpAmp → Mux → ADC
Identical circuit to envelope CV. 1% resistors sufficient.
Clipping note: Standard stage (-5V..+5V) clips at signals >5V.
Firmware Requirements
- Hysteresis: Stepped signal with ADC noise between steps. Software hysteresis (e.g., ±2 LSB tolerance band) prevents flickering at step boundaries.
- No smoothing of the actual signal — step transitions must be preserved
- Sample rate uncritical (DC signal), a few hundred Hz suffice