Sounds like: A deep pitch drop into the sub range, felt more than heard.
A deep, felt-more-than-heard pitch drop from a high-ish note down to sub territory over a second or two — used as a transition hit or a weighty accent.
Open this patch in the interactive PatchpadCorrected: the original version routed an LFO to a 'PITCH' destination that doesn't exist (Digitone II's FM TONE machine has no pitch destination for its LFOs). The authentic mechanism is a different machine: Digitone II's FM DRUM machine has a built-in pitch sweep — STIM sets the sweep time (lower = shorter) and SDEP the sweep depth — which is exactly a one-shot pitch fall from high to sub, no LFO hack needed. STIM and SDEP high give the slow, deep 1-2 second fall; both operators' MOD are 0 and both waveforms are Sine for a pure sub-weight tone, with body DEC long and the transient/noise levels (TLEV/NLEV) off. Light FX-page Overdrive keeps the low end audible as the pitch drops. Parameter values (TUNE/STIM/SDEP scales aren't documented) are starting points to adjust by ear.
SY RAW's dual Sine waveforms give a plain, minimal-harmonic carrier suited to sub content. Corrected: this LFO used to target an invented 'Pitch' destination — Syntakt's LFO destination list (manual Appendix C) has no direct pitch option, so it now targets the machine's own TUNE knob (parameter 1), the real route to pitch modulation. (For hard one-shot pitch falls Syntakt also has native sweeps: BD MODERN's SWEP sets pitch-sweep depth and time.)
LFO 2's destination is hardwired to oscillator pitch via its own section's Depth knob, so no Mod Matrix routing is needed. ONE SHOT plus a slow Ramp and large negative Depth turns it into a single ~1-2 second downward pitch fall rather than a repeating cycle. Light Distortion keeps the falling low end audible rather than disappearing as it nears sub range.
Osc 1 is Bass: Wave is Saturate, Timbre is Fold and Shape is Noise. Mod Matrix: the CycEnv row to the Pitch 1+2 column at -90. The Cycling Envelope in Env mode with a slow Fall gives a genuine one-shot pitch-fall source, routed to Oscillator Pitch through the Mod Matrix at a large negative amount for the multi-octave drop. The standard ENVELOPE's Decay is matched to the Cycling Envelope's Fall length so amplitude and pitch finish falling together. Light Distortion keeps the falling low end audible. Values are on MiniFreak's native 0-100 scale.
M1 in Envelope mode with a slow D/R gives a real one-shot pitch-fall source, routed to CV1 (pitch) -- because DEST is a CV/pitch destination, LVL is scaled in semitones rather than the usual 0-100, so -24 is a full two-octave downward drop over roughly the same length as the AMP ADSR's Decay.
Envelope 2 is pre-wired to the Amp, so the pitch-fall needs one of the free-assign Envelope 3/4/5 slots routed to pitch via the Mod Matrix -- Envelope 3's Decay is matched to Envelope 2's so amplitude and pitch fall together over the same ~1.5s window. -128 depth is the full negative range; the manual lists Osc Pitch modulation as +/-12 semitones, so this is a one-octave fall at most -- pitch it an octave or two higher, or add Osc SEMI, if you want a longer drop.
The pitch-envelope-to-pitch routing is the whole patch — if a synth's pitch envelope range is too short to cover a full 1-2 second fall, extend it with a slower LFO ramp routed to pitch instead, one-shot triggered.