Sounds like: A note that swells up to a peak and cuts off, like a reversed pluck.
A pluck played backwards, effectively — the note swells up to a peak rather than snapping and decaying, then cuts off cleanly. Useful as a rhythmic anticipation element leading into a downbeat.
Open this patch in the interactive PatchpadOperator A (ratio 2.00, level ~20) adds saw-like brightness without a metallic edge -- the AMP page's own long Attack (~80, zero Decay, full Sustain) does the actual swelling, not the FM modulator. FLTR's Attack is matched to the AMP page so the filter opens in step with the swell. The note holds at full sustain until cut by the trig length.
AMP PAGE 2's MODE must be set to ADSR (the default for SY machines, but drum machines default to AHD), so AMP PAGE 1's long Attack and full Sustain actually hold rather than the machine falling straight into its default Hold/Decay behavior -- easy to silently get wrong when translating a swelling shape. FLTR's own Attack mirrors the amp swell.
FILTER's SOURCE is set to Amp Env rather than a separate Mod Envelope, so the same long-Attack swell shapes both loudness and brightness together. Summit's Attack times are on a nonlinear exponential curve -- 80 lands in the several-hundred-ms range appropriate for a clear, gradual swell, dial in by ear.
Osc 1 is BasicWaves with Morph at 50 (pure sawtooth): the Morph knob runs from a square (0) through a sawtooth (50) to a double sawtooth an octave up (100), Sym only changes the pulse width below 50, and Sub adds a sine an octave down (0 here). The same Envelope also swells the filter open via ANALOG FILTER's ENV/VELO 20 above, mirroring the amp swell. Note length in the sequencer matters as much as the envelope: the note must be cut at the swell's peak for the 'reverse pluck' effect to read clearly. Values are on MiniFreak's native 0-100 scale.
AMP TIME and FILTER TIME on the front panel are set toward their slower end so the ADSR pages' own Attack values (already fairly long numbers) stretch out into a clearly audible swell rather than a quick fade-in. Front-panel knobs are physically unmarked, so WAVE/CUTOFF/RESON/EG LEVEL/FILTER TIME/AMP TIME are described by clock position, not a percentage; the ADSR page numbers use Typhon's usual 0-100 convention (inferred by consistency, see conventions notes).
Envelope 1 (pre-wired to Filter 1) and Envelope 2 (pre-wired to Amp) use matched long Attack stages with zero Decay and full Sustain (128.0, Hydrasynth's DAHDSR sustain is a level not a time) for the swell-then-hold shape. Note length matters as much as the envelope here -- the note must be cut (gated) at the swell's peak for the 'reverse pluck' effect to read clearly.
Note length in the sequencer matters as much as the envelope here — the note must be cut (gated) at the swell's peak for the 'reverse pluck' effect to read clearly, rather than left to sustain indefinitely.