Analog oscillator

ATMOSYNTH built-in module

The oscillator of an analog monosynth as one module: a wave that travels from a triangle to a narrow pulse, a sub oscillator under it, and the two things that make a hardware oscillator sound unlike a digital one — it does not start each note where the last one started, and its pitch never quite sits still. Wave travels triangle, sawtooth, square at nothing to two, each two neighbours mixed sample for sample between, so turning it is a sound changing shape rather than being swapped. From two to three the square narrows instead, from half of each cycle to a tenth: thinner, more nasal, and quieter as it goes. Wave is an input as well, and Wave amount is how far a signal there moves it — an envelope on it brightens the start of a note, and an LFO on it past two is pulse width modulation. The sub is a square one octave below, or two, and not an oscillator of its own: it changes sides each time the wave comes round, or every second time, so it cannot drift against it. Sub level mixes it into Out. Sub is an output too, carrying the sub alone at full level whatever Sub level says, so it can have a filter of its own. Phase is where a note starts its wave. At free each note starts somewhere else in its cycle, as an analog oscillator does, since it never stopped running between notes: no two attacks are quite alike, and two of these never meet the same way twice. At reset every note starts where the other oscillators here start theirs, the triangle and sawtooth at nothing on their way up and the square at the start of its high half, so every attack is the same one — what a tight bass or a pluck wants. Drift is how far the pitch wanders, in cents: slowly, a new direction every third of a second or so, glided to rather than stepped. It is what makes two analog oscillators beat against each other and a chord of them breathe. At nothing the pitch is the note's. Sync is an input: whatever is patched there starts the wave over on its rising zero crossings, the rule the sync oscillator's Sync input answers to, and the pitch heard becomes that while Detune moves the timbre. While something syncs it the sub divides that instead, so it stays under the pitch heard. An empty Sync input does nothing. Detune works as on the other oscillators: the knob reaches four octaves either side of the note, so 1200 is an octave switch, and what is patched into Detune moves it as far again by Detune amount. This module carries code because the vocabulary's oscillator has no phase anything can reach: nothing can divide its cycles into a sub, tell it where to start or start it over. Every edge and corner is band-limited where it falls between two samples, so the top of the keyboard stays a sound rather than folding into tones at no harmonic of anything.