Sounds like: Notes that blur completely into one endless, shifting reverb cloud.
A pad whose dry signal barely matters — the reverb is pushed so far that individual notes blur into a continuous, shifting wash. The source tone should be simple; the effect chain does the real work.
Open this patch in the interactive PatchpadALGO 1 is the plainest possible voice -- a single unmodulated carrier, deliberately unremarkable since the reverb is doing all the real work. REV on the FX page is a per-track send level only -- the reverb's own Time/Decay/Size live on the pattern-wide Reverb page, not here, so push that pattern-level decay and size as far as they'll go too; REV 127 alone won't reach the full wash without that pattern-level setting also being maxed. ALGO 1 routes operator A (and B) into carrier C, so LEV (A) and LEV (B) are set to 0 on SYN page 2 and MIX is -64 (the X output, C only): that leaves C a plain, unmodulated carrier.
SY RAW's plain dual Sine waveforms keep the dry source as unremarkable as possible, matching the brief that the source tone barely matters here. AMP PAGE 2's MODE must be ADSR (the default for SY machines, but drum machines default to AHD), for the sustain to hold at all. Like Digitone II, REV on AMP PAGE 1 is only a send level -- the pattern-wide Reverb page's own Time/Decay/Size need pushing too.
A plain sine oscillator keeps the dry source deliberately unremarkable. REVERB TIME/LEVEL both pushed to maximum with REVERB SIZE at its largest preset is as far as Summit's onboard reverb goes -- if that still isn't wash enough, route to an external reverb send instead.
Osc 1 is SuperWave used as a clean sine: Detune and the copies' volume are both 0, so it is a single sine wave. MiniFreak has real onboard Reverb and Delay across 3 independent Digital Effects slots, so both can run simultaneously here rather than needing an external send -- a genuine capability advantage for this patch over synths with sparser onboard effects. Values are on MiniFreak's native 0-100 scale.
Typhon does have real onboard effects, including this granular Cloud Reverb -- pushed to its extremes (SIZE and FEED maxed, MIX near-total) it's genuinely the most wash-like reverb algorithm in this whole library, arguably a better fit for this specific patch than the plainer Large/Soft Reverb types. FX3 can only run Delay or Reverb, never both, but this patch doesn't need a separate delay anyway.
The REVERB module's TIME set to Freeze (indefinite sustain, rather than a fixed decay length) is Hydrasynth's most literal match for 'individual notes blur into a continuous wash' -- genuinely different from just a very long decay time. Cloud-type reverb is Hydrasynth's most diffuse, granular-leaning algorithm, the closest real match to an ambient wash character.
This is really an effects patch more than a sound-design patch — the dry oscillator settings barely matter, the reverb settings are the entire point. An external reverb unit/send is a legitimate substitute on any synth whose onboard reverb doesn't go far enough.