Reverb: parameters and use in the mix

What it is and how it works

In a room, sound reaches the listener in three stages: the direct sound; the early reflections (ER: the first bounces off walls, floor and ceiling, within the first 5–80 ms), which the brain uses to judge size and distance; and the tail (late reverb), a dense cloud of decaying reflections. An artificial reverb recreates these stages with algorithms (networks of delays, allpass filters and feedback: algorithmic) or with a recording of the response of a real space (convolution, impulse response).

In the mix, reverb serves for: depth (front/back), shared space (gluing instruments into the same environment), size and sustain (bigger vocals and instruments), character and effect (1970s plate, 1980s gated, ambient shimmer).

Parameters one by one

• Decay / RT60: the time in which the tail drops by 60 dB. Small room 0.3–0.8 s; medium room 0.8–1.5 s; plate 1.2–2.5 s; hall 1.8–3.5 s; ambient 4–20 s (Fruity Reeverb 2 goes up to 20 s).
• Pre-delay: the gap between the direct sound and the start of the reverb. It separates the source from the space: with 20–40 ms (or 1/64–1/32 in time) the vocal stays "in front" even with a long reverb. Pre-delay 0 = source inside the space, further away.
• Size / Room size: perceived size (spacing of the reflections). In LuxeVerb, Size doesn't change the decay: 0–10 sounds like plate/electromechanical, 10–50 acoustic rooms, above 50 enormous spaces.
• Diffusion / Density: low = distinct, "grainy" reflections (good on pads and slow vocals, bad on percussion); high = smooth tail (percussion, drums).
• Early reflections: level and type of the early reflections. High = sense of a room and closeness to the walls; low = "pure" tail. In Fruity Reeverb 2: ER.
• Damping / High damping / Brightness: how quickly the highs decay relative to the mids: more damping = a room with soft surfaces, a warmer and less sibilant reverb. In Fruity Reeverb 2: DAMP; in LuxeVerb: Brightness.
• Bass multiplier and crossover: relative decay of the lows (Fruity Reeverb 2: BASS and CROSS). Long lows = big but muddy space: in pop and hip hop usually < 1×.
• Modulation: slightly varies the delay lines for a livelier, less metallic tail (Fruity Reeverb 2: SPEED and MOD; LuxeVerb: Mod Amp and Mod Freq). Low on pitched instruments like piano, higher on pads and vocals.
• Width / Stereo separation: width of the return (Fruity Reeverb 2: SEP; LuxeVerb: Width, default 1.25).
• Input filters: Low cut and High cut before the reverb (Fruity Reeverb 2: L.CUT, H.CUT; LuxeVerb: Input Low/High Cut).
• Dry/Wet: on a send, Dry 0% and Wet 100% (as the Fruity Reeverb 2 manual recommends for send tracks).
• Freeze: freezes the tail (LuxeVerb: Freeze, Sustain).
• Envelope/ducking/gate: LuxeVerb has an envelope that modulates wet or decay: positive scale = gated reverb, negative = ducking.

Tempo-synced decay and pre-delay

• Decay: for vocals and main instruments, the tail should end (or drop a lot) before the next strong hit that matters: often a quarter note or half a bar in fast songs, 1–2 bars in ballads.
• Pre-delay: 1/64 = 60,000 / BPM / 16. At 120 BPM: 1/64 ≈ 31 ms, 1/128 ≈ 16 ms. At 90 BPM: 1/64 ≈ 42 ms.
• Reverb that "pumps" in time: sidechain compressor from the kick on the return (EDM).

How to organize reverbs (sends)

Create 2–4 dedicated mixer tracks in FL, each with a reverb at 100% wet, and feed them from the tracks with the send knobs:

1. Short room (0.4–0.8 s): glues drums, guitars, percussion into the same environment.
2. Plate (1.2–2 s, pre-delay 20–40 ms): vocal and snare.
3. Hall or long reverb (2–3.5 s): pads, strings, effects, choruses.
4. Optional: effect reverb (shimmer, gated, spring) for specific moments.

On the return: EQ (HP 150–400 Hz, LP 6–10 kHz), optional de-esser at the input, sidechain compression from the vocal or kick, level automation between verse and chorus.

Starting settings by instrument

By genre

• Trap, drill, modern rap: vocal almost dry and very close; long reverbs only on ad-libs, melodies and throws.
• Pop: plate on vocal, room on drums, hall on pads; automation between sections.
• R&B: longer, softer plates and halls on the vocal and backing vocals.
• Rock: room on the drums (also gated), plate on the vocal.
• EDM: long halls with sidechain from the kick; huge reverbs in breakdowns.
• Jazz, acoustic, orchestral: a single realistic space (hall or chamber, often convolution) for everything, with small differences in level and pre-delay.
• Lo-fi: dark spring and plate.

Common mistakes

• Reverb as an insert on every track: different spaces, a confused mix and wasted CPU.
• No HP on the return: mud at 100–300 Hz.
• Zero pre-delay on the vocal with a long decay: the vocal moves away and loses intelligibility.
• Reverb on bass and 808: a confused low end.
• Level set in solo: a reverb that sounds right in the full mix becomes enormous when the arrangement thins out. Automate.
• Sibilants in the reverb: de-esser at the input.

How to hear it

• Raise the send until you clearly hear the reverb, then lower it until you no longer hear it as an effect: the right value is just above that point. Mute it: if the vocal becomes "naked", it was working.
• Listen to the reverb return alone: it must be clean, without mud and without sibilants.