DuskVerb

DuskVerb is a free algorithmic reverb that gives you seven genuinely different DSP engines under the same UI — separate topologies you can audition like swapping hardware boxes, not flavours of the same algorithm. 35+ factory presets anchored to real studio gear, a hero DECAY visualisation, and the controls you need to shape anything from a tight slap to an infinite shimmering pad.

Overview

The starting point is the engine selector. Each engine is a distinct DSP architecture with its own delay structure, feedback topology, and modulation character. Pick one, then dial in size, decay, modulation, damping, early reflections, and a few output filters. The factory presets are tuned per-engine to match recognisable hardware references, but you’re free to switch engines on any preset and get a meaningfully different sound.

Every engine pre-allocates at construction so changing engines is real-time safe — no clicks, no dropouts, no buffer underruns. Modulation across all four engines uses a smoothstep-interpolated random-walk LFO, which gives the aperiodic shimmer of high-end hardware random reverbs (Lexicon 480L, Eventide ModFactor) without the audible cyclic warble of sine modulation.

Engines

Vintage Plate (Dattorro) — A 2-allpass cross-coupled tank built on the Dattorro 1997 plate topology. Bright, dense, smooth. The classic studio vocal plate sound. Use it on snares, vocals, the mix bus.

High Density (6-AP) — A 6-allpass density cascade tank. Diffuses the input fast and produces lush, dense halls and ambient pads. Lower size knob settings give you intimate chambers; higher settings open up to cathedral-scale spaces.

Quad Room (QuadTank) — Four cross-coupled tanks with 48 total taps. Designed for realistic rooms with strong early reflections and clean late decay. Great for drums, dialog, and anything where you want a sense of physical space without a long tail.

Realistic Space (FDN) — A 16-channel Hadamard feedback delay network. The biggest, most spacious-sounding engine. Use it for halls, ambient washes, and effects that need real breadth. The Hadamard mixing matrix gives natural-sounding mode density.

Spring Tank (6G15) — Analog spring-reverb voicing modeled after the Fender 6G15. Boingy, characterful, perfect for guitar amps, surf textures, and anywhere a hardware spring’s “drip” character is the sound.

Non-Linear (RMX16) — Gated reverb with a sidechain-style envelope follower. The iconic Phil Collins / Hugh Padgham gated-snare sound. Big-room reverb shaped by the dry signal’s transients — the room blooms in for the snare hit, then cuts off cleanly. Ships with “1981 Gated Snare” and “In The Air Tonight” presets.

Shimmer (Eno FDN) — Pitch-shifted feedback cascade in the spirit of Brian Eno and Daniel Lanois’s 1980s outboard rig (AMS DMX → Lexicon 224 → feedback aux). Octave-up shimmer reverbs for ambient pads, sustained guitars, drone work. New in v0.5.0: Black Hole and Deep Blue Day presets clone Valhalla Shimmer’s BlackHole and DeepBlueDay factory voicings.

Controls

Hero DECAY — large concentric-ring readout. Drag vertically. Sets RT60 from 0.2 s to 30 s.

Pre-Delay — gap before the reverb starts (with tempo sync). Use STEED-style 18 ms for vintage vocals, longer for modern pop spaces.

Size — virtual room dimensions. Affects echo density and spacing.

Depth / Rate — modulation amount and speed. A little goes a long way for keeping the tail sounding natural and avoiding metallic resonances.

Treble Mult / Bass Mult / Crossover — independent decay multipliers for the highs and lows, with an adjustable crossover frequency. <1× treble = natural air absorption; >1× bass = bass rings longer than mids.

Diffusion — input smearing. Low = grainy slap-back echoes; high = smooth wash.

ER Level / ER Size — early reflection level and spacing. The early reflections define the perceived room shape.

Lo Cut / Hi Cut — wet-signal filters.

Width — stereo width 0–200%.

Mono < — sums the wet signal to mono below the cutoff. Use 80–150 Hz to keep low-end tight on busy mixes; 20 Hz = bypass.

Trim — output gain offset.

Freeze — mutes input, loops the existing tail indefinitely. Useful for ambient pads, risers, and effects.

Bus Mode — outputs 100% wet regardless of DRY/WET. Use on a send/return aux.

Factory Presets (35+)

Plates — Vocal Plate, Rich Plate, Gold Plate, Fat Pop Plate, Modulated Plate, Vintage Vocal Plate, Snare Plate XL Springs — Surf ‘63 Spring, Tank Drip Halls — Utility Hall, Bright Studio Hall, Bright Hall, Smooth Concert Hall, Blade Runner Concert, Deep Blue, Lush Dark Hall, Vocal Hall, Cathedral, Blade Runner 224 Chambers — Realistic Chamber, Wood Chamber Rooms — 80s Non-Lin Drum, Vocal Booth, Tight Drum Room, Studio Room, Ambience, PCM Drum Room, 1981 Gated Snare, In The Air Tonight, Reverse Taps Ambient — Mobius Pad, Ambient Swell, Black Hole, Infinite Blackhole Shimmer — Cascading Heaven, Deep Blue Day

Each preset is anchored to a recognisable hardware reference (Lexicon 224 Blade Runner, EMT 140 plate, AMS RMX16 non-lin drum, Bricasti M7 cathedral, Eventide Blackhole infinite, Valhalla Shimmer BlackHole / DeepBlueDay). The UI’s accent colour shifts to match the active engine, so you always know which architecture you’re hearing. The preset dropdown uses nested submenus so the categories stay scannable as the library grows.

You can also save, load, and delete your own presets from the menu — they live in ~/Library/Application Support/Dusk Audio/DuskVerb/Presets/ (macOS) and the equivalent locations on Linux/Windows.

Under the Hood

Every engine ships with three-band damping (low-shelf + high-shelf 2nd-order RBJ biquads in a Lexicon-style serial cascade). All delay reads use cubic Hermite interpolation. Parameters smooth per-sample to avoid automation zipper noise. Modulation is generated by a smoothstep-interpolated random-walk LFO, normalised to a consistent ±16-sample excursion across the engines. The FDN uses a 16×16 Hadamard mixing matrix; QuadTank cross-couples four allpass tanks with prime-spaced delay lines; the 6-AP density cascade is structurally similar to Lexicon hall density-AP conventions; the Shimmer engine wraps a granular pitch shifter around an FDN tank with a 50 ms feedback delay decoupled from the host block size. Audio thread is allocation-free and lock-free; engine switching only flips a pointer.

DuskVerb is sample-rate independent. All base delay lengths and modulation excursions are tuned at 44.1 kHz and scale linearly with the host sample rate. Tested at 44.1 / 48 / 96 / 192 kHz.

DAW Compatibility

Tested in Logic Pro (AU), Reaper (VST3/LV2), and Ardour (LV2). Should also work in Bitwig, Studio One, FL Studio, Ableton Live, Cubase, and GarageBand.

Installation

Linux

VST3: ~/.vst3/DuskVerb.vst3
LV2:  ~/.lv2/DuskVerb.lv2

Windows

VST3: C:\Program Files\Common Files\VST3\DuskVerb.vst3

macOS

VST3: ~/Library/Audio/Plug-Ins/VST3/DuskVerb.vst3
AU:   ~/Library/Audio/Plug-Ins/Components/DuskVerb.component

Open Source

DuskVerb is open source under GPL-2.0. View the source, report issues, or contribute on GitHub.