Reverb & Delay
Dry studio recordings and synths sound like they're playing in a vacuum. Reverb and delay put them in a space. They create depth, size and atmosphere, and they glue separate parts into one world.
What is Reverb?
When you clap in a room, you hear the clap directly, then thousands of reflections off the walls, floor and ceiling. Those reflections blend into a smooth, fading wash called reverberation, or reverb.
A reverb has three parts in time:
- Direct sound: the original, dry signal.
- Early reflections: the first distinct echoes, arriving in roughly the first 5–100 ms. They tell your brain how big the room is and where the sound sits in it.
- Tail (late reverb): a dense, smooth wash that fades away.
Reverb Types
| Type | How it works | Sound | Great on |
|---|---|---|---|
| Room | Simulates a small to medium room | Short (0.3–1 s), natural, subtle | Drums, acoustic instruments, "glue" |
| Hall | Simulates a concert hall | Long (1.5–3+ s), lush, smooth | Strings, pads, ballad vocals |
| Plate | Originally a large vibrating metal sheet | Bright, dense, smooth; no real "room" | Vocals and snares (a pop classic) |
| Spring | A signal sent through metal springs, as in guitar amps | Twangy, boingy, lo-fi | Guitars, dub, surf, retro sounds |
| Chamber | A dedicated echo room with a speaker and microphones | Warm, dense, mid-length | Vocals, classic 50s–70s sound |
| Convolution | Uses a recording (an impulse response) of a real space or device | Very realistic | Placing sounds in real rooms, film work |
Rooms, halls, plates, springs and chambers usually come as algorithmic reverbs, which create reflections with math. They're flexible and cheap on CPU. Convolution reverbs are realistic but less tweakable.
Reverb Parameters
- Decay time (RT60): how long the tail takes to fade by 60 dB. Short decays (under 1 s) sound tight; long ones (over 2 s) sound big and washy.
- Pre-delay: the gap between the dry sound and the start of the reverb, usually 0–100 ms. A pre-delay of 20–60 ms keeps a vocal clear and upfront while the reverb blooms behind it.
- Size: how big the simulated space is. Often linked to decay and early reflection spacing.
- Damping: how quickly high frequencies die away in the tail. Real rooms absorb highs, so more damping sounds darker and more natural.
- Diffusion: how dense the reflections are. Low diffusion sounds grainy and echoey; high diffusion sounds smooth.
- Early reflections level: more makes the sound feel more "in a room" and further away.
- Mix (dry/wet): the balance between the original and the reverb. Set to
100% wetwhen used on a send.
Sends vs. Inserts
You can put reverb on a track as an insert (directly on the channel) or on a send (also called an aux or return track that many channels feed).
- Sends are the standard for reverb and delay. One reverb serves many tracks, which saves CPU and makes everything sound like it's in the same space. You can also EQ or compress the reverb on its own.
- Inserts are fine for one-off creative effects on a single sound, like a huge reverb on a single FX hit. Lower the mix knob to taste.
EQ the reverb return
Low frequencies in a reverb tail make a mix muddy fast. Put an EQ on the reverb return and:
- High-pass at about
200–600 Hz. The reverb keeps its space, but stops smearing the kick and bass. - Low-pass at about
6–10 kHzto soften harsh sibilance and make the reverb sit behind the dry sound.
Many engineers set up two or three shared reverbs at the start of every mix: a short room (around 0.8 s) for drums and glue, a plate (around 1.5–2 s) for vocals and snare, and a long hall (2.5 s or more) for pads and special moments.
Creating Depth
A mix has three dimensions: left–right (panning), up–down (frequency), and front-to-back (depth). To push a sound further back:
| Closer (front) | Further (back) |
|---|---|
| Louder | Quieter |
| Drier (less reverb) | Wetter (more reverb) |
| More pre-delay | Less pre-delay, more early reflections |
| Brighter (more highs) | Darker (highs rolled off) |
| More transient, more compression | Softer transients |
A typical layout: lead vocal and kick at the front, drums and bass just behind, pads and backing vocals further back.
What is Delay?
Delay records the sound and plays it back later, creating distinct echoes. Two controls matter most:
- Time: the gap between the original and each echo, in ms or note values.
- Feedback: how much of the echo is fed back in to create more echoes. 0% gives one echo; 30–50% gives several fading repeats; near 100% repeats almost forever and can run away.
Delay types
| Type | Settings | Use |
|---|---|---|
| Slapback | One echo, 60–150 ms, little or no feedback | Rockabilly and classic rock vocals, thickening guitars |
| Tempo-synced | Time set to a note value (1/4, 1/8, dotted 1/8) | Echoes that groove with the track |
| Ping-pong | Echoes bounce between left and right | Width and movement on leads, vocal throws |
| Tape / analog | Each repeat gets darker, softer and slightly wobbly | Warm, vintage echo; dub; lo-fi |
Delay Time Formula
To sync a delay to the song, use this formula for a quarter note:
Quarter-note delay time
Halve it for 1/8 notes, halve again for 1/16. Multiply by 1.5 for dotted notes, and by 2/3 for triplets.
| Note value | At 120 BPM |
|---|---|
| 1/2 note | 1000 ms |
| Dotted 1/4 | 750 ms |
| 1/4 note | 500 ms |
| 1/4 triplet | 333.3 ms |
| Dotted 1/8 | 375 ms |
| 1/8 note | 250 ms |
| 1/8 triplet | 166.7 ms |
| 1/16 note | 125 ms |
Most DAW delays have a sync button that does this for you, but the formula is still useful for pre-delay, compressor release times, and hardware.
At 100 BPM, a quarter-note delay lasts ms, and a 1/8-note delay lasts ms.
The delay control that sets how many repeats you hear is called .
Throws and Creative Tricks
A throw is a delay or reverb applied to just one word, note or hit, usually by automating a send up for a moment. The classic example is the last word of a vocal line echoing into the gap: "...tonight... tonight... tonight".
- Delay throw: automate the send to a 1/4 or dotted 1/8 delay up for the last word of a phrase.
- Reverb throw: send a single snare hit to a long reverb at the end of a section.
- Dotted 1/8 on guitar: a famous trick for shimmering, rhythmic guitar parts (heard in many of The Edge's parts with U2).
- Sidechained reverb: duck the reverb return with the dry vocal so the reverb blooms in the gaps. See Sidechain & Ducking.
- Create two return/aux tracks (Ableton: Return tracks, FL Studio: a free Mixer insert used as a send, Logic: Aux via a channel's Send slot).
- Put a plate reverb (about 1.8 s decay, 30 ms pre-delay, 100% wet) on the first. Add an EQ after it: high-pass at 400 Hz, low-pass at 8 kHz.
- Put a tempo-synced 1/4 delay (feedback 30%, 100% wet) on the second, with the same EQ.
- Send the vocal or lead to both at a low amount. Raise each send until you hear it, then back off slightly.
- Automate the delay send up for the last word of one phrase to make a throw.
Too much reverb on everything. The mix sounds washed out and distant, and the lead loses focus. If you can clearly hear the reverb as a separate effect on every part, it's usually too much. Solo-check less; judge reverb in the full mix.
1. What does pre-delay do on a reverb?
- Sets how long the tail lasts
- Adds a gap before the reverb starts, keeping the dry sound clearer
- Removes low frequencies from the reverb
- Repeats the sound in time with the tempo
Pre-delay separates the dry sound from the reverb, so a vocal stays upfront while the space blooms behind it.
2. Why is reverb usually placed on a send rather than an insert?
- Inserts can't run reverb plugins
- Sends make the reverb mono
- One shared reverb saves CPU and puts many tracks in the same space
- Sends always sound brighter
Sends let several tracks share one reverb, which you can also EQ and process separately.
3. What is the quarter-note delay time at 120 BPM?
- 250 ms
- 375 ms
- 1000 ms
- 500 ms
60000 ÷ 120 = 500 ms.
4. Which reverb type was originally a large vibrating metal sheet?
- Plate
- Spring
- Chamber
- Hall
Plate reverbs sent the signal through a suspended metal plate. They're bright and dense, a classic on vocals and snares.
5. How do you push a sound further back in the mix?
- Make it louder and brighter
- Remove all reverb
- Add more pre-delay and boost the highs
- Make it quieter, darker and wetter
Distant sounds are quieter, have fewer highs and more reverb compared to their direct sound.