The Overtone Scan

The controls

The scan gives you a handful of parameters:

• Range — a top and a bottom. The scan only travels between these two partials, so you can keep it down in the low harmonics for subtle movement or let it range across the whole stack for something dramatic.
• Speed — how fast the focus sweeps.
• Shape — the contour of the sweep, which changes how the focus accelerates and turns around.
• Focus — how tight the emphasis is. A narrow focus picks out partials sharply, almost like a resonant peak walking the spectrum; a wide focus blurs several together for a gentler swell.

Set the range narrow and the focus tight and you get a clear, pitched sweep. Open the range and widen the focus and it becomes a slow tidal motion across the whole sound.

It’s also LFO 1

Under the hood, the overtone scan is the synth’s LFO 1. That’s worth knowing for two reasons. First, it means the scan can be routed like any other modulation source if you want it driving something elsewhere in the synth. Second, it means that when you go looking at the modulation system later and wonder why LFO 1 seems to already be doing something — it’s this. (Modulation gets its own chapter; for now, just file away that the scan and LFO 1 are the same thing.)

What to Practice

• Build a full sawtooth in the partials matrix, then turn on the overtone scan with a wide range and a slow speed. Listen to the focus walk up and down the harmonics.
• Tighten the focus and shorten the range to the bottom few partials. Notice how it goes from a broad swell to a clear, pitched sweep.
• Try a fast speed with a narrow focus for a shimmering, restless texture — then slow it down and hear the same patch turn into something that breathes.