Tanel Teemusk

Software Developer · Tech Lead · iOS, macOS & Full-Stack

Helin Guide

Output and voices

The Output is the last node on the canvas. Every sound ends there, and it decides two things: how loud the whole patch is, and how many notes it plays at once.

Level, meters and the limiter

limiter ceiling (dashed)peaks that would go over are caught; leave some room anyway
The Output’s limiter holds peaks under its ceiling (the faded red tops never reach the speakers). Voices sets how many notes play at once.
  • Open the Output’s popup for its meters on a dB scale, the Level fader, the true peak and RMS readouts, and how much the limiter is taking off. The meters are solid up to the RMS level and paler up to the peak.
  • A look-ahead limiter at −1 dB with a soft clip catches peaks at the end of the chain, so a loud patch does not distort. Keep the meters out of the red anyway: the limiter is a safety net, and a patch that leans on it all the time sounds squashed.
  • If a sound ever goes numerically wrong, the Output goes silent for that moment instead of jumping to full volume.
  • In a host, the Output’s level is the Master parameter, so it can be automated.
  • The popup also shows the CPU load, the voices in use and the latency Helin reports to the host (1.5 ms).

Voices

key 1voice 1source × 3 unison, filter, ampkey 2voice 2source × 3 unison, filter, ampkey 3voice 3source × 3 unison, filter, ampOutputVoices: how many keys at once (1 to 16) · Unison: copies inside each voice (1 to 7)
Three keys, three voices. Each voice has its own copy of the chain; Unison stacks copies of the source inside it.

Every key you play gets a voice: its own copy of the sources, filters, amps and envelopes, so each note has its own filter sweep and its own fade. The voices then mix together before the effects. (Cables and modulation shows which nodes run per note.)

  • Voices on the Output sets how many notes the patch plays at once, from 1 to 16. Double-tap it for 8.
  • One voice makes the patch mono. A key played over a held one changes the pitch without restarting the envelope, and letting go slides back to the key you are still holding, like a mono synth.
  • Bass has Legato and Pluck: Legato plays one voice that slides between held keys, Pluck gives every note its own voice. If Legato left a patch at one voice, raise Voices on the Output to play chords again.
  • Unison is different: it stacks up to seven detuned copies of one source inside each voice, for width and thickness. Four keys with Unison at 3 is four voices, twelve oscillators.
  • Hold and the sustain pedal keep voices sounding after you let go of the keys.

Next: Effects