Audio Sync In
SyncsyncinLight CPU
PO/Volca sync slave — Schmitt-triggers audio pulses into Trig / Gate / BPM.
What it does
External clock follower — recovers Trig / Gate / pulse rate from PO/Volca-Sync pulses on an audio input.
A file-scope Schmitt trigger (two thresholds) tracks the incoming level; each rising edge emits a one-sample Trig and resets a sample counter, and the inter-pulse interval feeds an EMA-smoothed pulse-rate estimate (Hz). Pure inline DSP — no DaisySP class. Outputs only emit C++ for ports that are actually wired downstream.
Parameters
-
Thresh High
threshHighLevel an incoming pulse must reach to count as a rising edge and fire Trig. Raise it if noise or bleed from the other channel is producing phantom triggers; lower it if a quiet source is being missed entirely. It must stay above Thresh Low for the hysteresis to work.
-
Thresh Low
threshLowLevel the signal must fall back below before another rising edge can be detected. The gap between this and Thresh High is the hysteresis band, and it is what stops a noisy or slow-sloped pulse from triggering repeatedly on one edge. ⚠ Setting it equal to Thresh High removes the protection entirely.
-
Rate Smoothing
smoothHow heavily the measured pulse rate is averaged before it reaches the Pulse Hz output, as the coefficient of a running average. Low values smooth hard, so the reading is stable but lags a tempo change; high values follow a tempo change quickly but let the reading jitter between pulses. It affects only the rate estimate — Trig and Gate are unaffected.
Wire an Audio In channel into Audio In. A rising edge above Thresh High fires Trig (one sample) and raises Gate; it drops below Thresh Low (hysteresis rejects noise). Pulse Hz is the averaged pulse rate — at the Volca/PO 2 PPQN standard, BPM = Pulse Hz × 30. Codec round-trip latency is ~1 ms — fine for groovebox sync, marginal for sample-accurate modular timing.
Ports
In
-
Audio In
input
Out
-
Trig
trig -
Gate
gate -
Pulse Hz
bpm
Audio Control
Inputs
- Audio In
- Sync pulses from an Audio In channel (TRS cable from a Volca / PO / sequencer).
Outputs
- Trig
- One-sample pulse on each rising edge — drive envelopes / drums.
- Gate
- High between rising and falling edge (level).
- Pulse Hz
- EMA-averaged pulse rate. BPM = Hz × 60 / PPQN.
Rules and gotchas
- Thresholds / smoothing are baked at boot.
- Latency is one codec round-trip (~1 ms) — fine for Volca-class gear.