Sounds like: A soft, warm thumb-piano pluck with a rounded attack.
A warm, organic plucked tone with a soft, rounded attack — related to Marimba-style Pluck but even gentler and less percussive, closer to a thumb piano than a mallet instrument.
Open this patch in the interactive PatchpadOperator A's LEV is kept low (25) and its own DEC/END fall quickly to 0, so only a brief hint of the ratio-3.00 overtone colors the ratio-1.00 carrier before it drops out -- softer than Marimba-style Pluck's stronger modulator. The FLTR page stays mostly open with minimal resonance since the FM engine, not the filter, carries the character. The long AMP DEC gives the soft, rounded thumb-piano fade.
Syntakt's SY TONE machine is a two-operator FM voice (RATIO, FDBK, MOD, MENV), so FM is available on the melodic tracks. A low MOD amount adds the gentle overtone of a thumb-piano tine to a soft base tone, and a short MENV keeps that overtone at the attack. RATIO is by ear.
Summit has real FM: the panel FM section's Osc 1 > Osc 2 control sets how much Oscillator 1 frequency-modulates Oscillator 2's pitch, and its Source button picks Manual, Mod Env 2 or LFO 2 (the sources add together). Osc 1 is the modulator (its Mixer level is 0) and Osc 2 is the carrier; the Osc 1 : Osc 2 pitch ratio (set with Range and Coarse) decides whether the sidebands are harmonic or bell-like. Osc 1 at a ratio of 3:1 with a low FM depth and a short Mod Env 2 gives just a hint of thumb-piano tine overtone at the attack.
Osc 1 is Two Op. FM: Wave sets the ratio between the two operators (non-integer ratios are inharmonic and bell-like), Timbre is the modulation index and Shape is the feedback. ENV/VELO is kept low so the filter barely moves, keeping the attack soft rather than snappy, matching the soft, rounded ENVELOPE decay. Values are on MiniFreak's native 0-100 scale.
The softest, roundest version of this FM-pluck family -- Typhon has no FM/digital engine, so the sine-leaning WAVE blend plus a low EG LEVEL (the filter barely moves) stand in for the gentle overtone the FM-capable synths get from a real modulator. Front-panel knobs are physically unmarked, so WAVE/CUTOFF/RESON/EG LEVEL/FILTER TIME/AMP TIME are described by clock position, not a percentage.
Mutator 1's FM-Lin mode gives Oscillator 1 a real 2-operator FM modulator, kept at low Depth (20.0) for just a hint of overtone -- the same mechanism the manual describes for FM-style timbre shaping, distinct from the Harmonic mode used on brighter/metallic patches in this family. Filter 1 stays nearly wide open with minimal Env 1 Amount so the attack reads soft rather than percussive.
The gentlest member of the FM-pluck family in this library (Classic FM Pluck → Marimba-style Pluck → Kalimba-style Pluck, in decreasing modulator intensity).