Vast Reverb

A continuously-variable reverb built on a feedback delay network. From a tight, boxy chamber to a slowly-decaying cathedral, Vast sweeps smoothly across the whole space in between — and it stays musical and alive the whole way thanks to gentle internal modulation.

How it works

Four delay lines feed back through a Hadamard mixing matrix to build up a dense, diffuse tail. Size scales all four line lengths together to set the apparent dimensions of the room, while Decay sets the RT60 (the time the tail takes to fade) in seconds — the two are decoupled, so you can grow a giant space without it ringing forever, or hold a tiny room for ages. Diffuse runs the input through a chain of allpass filters first, smearing sharp transients into the tail so percussion melts in rather than slapping back. A one-pole filter in each feedback line darkens the tail a little more on every pass — Damp sets where that roll-off sits, from a soft, distant space to a bright, glassy one — while a slow per-line LFO, its depth set by Mod, nudges each read position to give the tail its shimmer and motion. The left and right inputs are summed into a single shared tank, then read back through two decorrelated taps for genuine stereo width.

Controls

  • Size — the dimensions of the space, from a small chamber to a vast hall. Decay time stays constant as you turn it, so changes in size don't change how long the tail lasts.
  • Decay — how long the tail rings, from a short 0.3 s slap to a near-infinite 30 s hold at the top of the dial.
  • Diffuse — how much the input is smeared before it enters the tank. At 0 the source hits the reverb dry and direct; turn it up to soften transients and thicken the early reflections into a wash.
  • Damp — the tone of the tail. A one-pole filter in the feedback path rolls off the highs a little more on every pass; down low around 1 kHz the highs are soaked away for a dark, distant space, while up near 18 kHz the tank stays bright and glassy.
  • Mod — how deeply the internal LFOs nudge the delay lines, from a 0-sample static, metallic tail to a deep 8-sample shimmering, chorused wash. A touch keeps the reverb breathing and alive; a lot starts to detune and swim.
  • Mix — wet/dry blend, from fully dry to pure reverb.

Inputs & outputs

  • In L / In R — the stereo source to drench. The two channels are summed into one tank, so mono and stereo sources both work.
  • Size / Decay / Diffuse / Damp / Mod / Mix CV — voltage control over each knob; patch an envelope or LFO to swell the space, modulate the decay or diffusion, open and close the tail's tone, deepen the shimmer, or duck the wet level in time with the music.
  • Out L / Out R — the stereo result. The two taps are decorrelated, so the output has real width rather than a centred mono blob.

Tips

  • Push Decay to maximum for a frozen, near-infinite drone bed — feed it short stabs and let them pile into a shimmering wash.
  • Modulating Size CV slowly turns a static space into a breathing, morphing one — sweep it under a sustained pad and the room itself becomes part of the sound.
  • Keep Mix low on drums and bass for a sense of room without washing out the transients.
  • Crank Diffuse on drums or plucks to dissolve their attack into the tail — the classic smooth, transient-free "ambience" sound — or leave it at 0 for a tighter, more defined space.
  • Pull Damp down toward 1 kHz for a dark, vintage tail that tucks behind the mix, or open it up toward 18 kHz for a bright, modern space that sits forward and glassy.