Sounds like: A mid-range pad with a deep sub layer filling out the low end.
A standard mid-register pad with a dedicated low sine layer underneath — the pad's harmonic content stays in the mid-upper range while the sub layer fills out the low end separately, avoiding a muddy low-mid pad.
Open this patch in the interactive PatchpadDigitone II's ALGO 3 gives three plain carriers (C, B2, B1) when the FM depth of A and B is off, so LEV (A) and LEV (B) are both 0. MIX -64 selects the X tap (C + B2), and DTUN, which offsets only the ratio of operators A and B2, detunes B2 against C so the pad voices beat against each other. DTUN below 64 is a very slight detune; above 64 is heavier. The sub track uses ALGO 4 instead of ALGO 1 specifically because ALGO 4's carrier is envelope-affected (ALGO 1's is not), so the same AMP-page attack shapes both tracks together. Keep the sub track's FLTR FREQ close to fully open (115) so the low end stays clean rather than getting filtered down like the pad. On the sub track, ALGO 4 is a serial chain B2 to B1 to A to C, so LEV (A) and LEV (B) are 0 and MIX is -64 (C only) to leave a plain sine.
SY RAW's plain two-waveform layout (not SY SWARM) keeps the pad track's own detune modest and controlled rather than a full supersaw spread. The sub track uses the same machine with LEV2 at 0 so only WAV1 sounds -- a single clean sine, TUNE dropped a full octave. AMP PAGE 2's MODE has to be set to ADSR on both tracks, or the SUS/REL values on AMP PAGE 1 are silently ignored (AHD has no sustain stage at all; SY machines default to ADSR, but drum machines default to AHD).
Layer B's Oscillator 1 RANGE set to 16' (one octave below the 8'-concert-pitch default) is what gives the clean sub layer -- a real footage transposition rather than a coarse-tune workaround. Layer A pairs OSC1/OSC2 both as saw for the pad body, FINE-detuned a few cents apart. Both layers' AMP ENVELOPE attack is matched so the pad and sub bloom together as one voice.
Osc 1 is SuperWave, the stacked-detuned-copies engine: Detune (25) sets the spread between the copies and the third knob (60) sets the copies' level against the original. Osc 2 is SuperWave used as a clean sine: Detune and the copies' volume are both 0, so it is a single sine wave. MiniFreak's two real oscillators let pad and sub sound simultaneously here, unlike a single-oscillator instrument -- but its one shared Analog Filter (unlike Summit/Hydrasynth's independently-filterable layers) means both layers pass through the same CUTOFF, so 65 is a deliberate compromise between the pad's own ~55 and the sub's near-open ~90 rather than the fully independent per-layer filtering the other synths get. Values are on MiniFreak's native 0-100 scale.
TUNE 2 pulled well below center is what gives VCO2 its octave-down sub role -- Typhon's knobs are unmarked, so 'roughly an octave' is a clock-position estimate to dial in by ear against VCO1, not a printed value. FILTER TIME and AMP TIME are both pulled toward their slow end so the real Filter/Amp ADSR attack values (40, on their own 0-100 scale) stretch out to match the moderate onset on both pad and sub. No FX page is used here -- this patch doesn't lean on Typhon's onboard chorus/reverb.
Mutator 1's WavStack mode (five detuned copies of OSC1's waveform, a real built-in unison thickener) is what gives the pad its 'detuned' body -- there's no separate second pad oscillator here. FILTER ROUTE is set to Parallel with the MIXER's FILTER ROUTING splitting OSC1 to Filter 1 and OSC2 to Filter 2, so the pad and sub can genuinely run at independent cutoffs (moderate on Filter 1, open on Filter 2) at the same time, unlike Digitone II/Syntakt's single per-track filter. Only ENVELOPE 2 (pre-wired to Amp) is used -- Filter 1/2's ENV 1 AMOUNT is left at 0 since both cutoffs stay static rather than sweeping.
MiniFreak's two real oscillators let pad and sub sound simultaneously, but its single shared Analog Filter (unlike Summit/Hydrasynth's independently-filterable layers) is a genuine limitation for this specific two-layer concept — noted honestly above rather than glossed over.