Reverb and delay basics: types, pre-delay, and sending versus inserting

Reverb and delay are the two effects that put a dry recording somewhere. Reverb makes it sound like it was played in a room, and delay repeats it so it seems to echo back. Both are easy to overdo, and most of the "my mix sounds washed out" problems we hear come from how they were routed rather than which plug-in was used.

This guide covers what the main controls do, the difference between pre-delay and delay, and why most engineers send to these effects rather than insert them on every track. We use the Ableton Live manual as our reference because it is public and precise, but the ideas carry over to any DAW. If you have not read it yet, our guide to compressor controls covers the other half of the basic mixing toolkit.

What is reverb, actually?

In a real space, sound bounces off walls, floors and furniture before it reaches your ears, and soft materials absorb some of it on the way. Ableton describes its Reverb device as an approximation of that process "with a combination of filters and modulated delay lines". Digital reverb is, underneath, a very dense cloud of short delays.

The manual splits a reverb into two parts, and it is worth learning them because almost every reverb plug-in uses the same idea:

• Early reflections are "the earliest echoes that you hear after they bounce off a room's walls, before the onset of the diffused reverberation tail". Their level and spacing give you the impression of the room's character.
• The tail (Ableton calls the section that makes it the Diffusion Network) is the smeared wash that follows. Its high and low shelving filters control how fast high and low frequencies die away; the manual says the high-frequency decay models absorption by air, walls and materials such as people and carpet.

The controls that matter most

Decay (often called reverb time) sets how long the tail lasts. In Ableton's Reverb it is the time for the tail "to drop to 1/1000th (-60 dB) of its initial amplitude". Long decays sound big and expensive in solo, and muddy under a full arrangement.

Size controls the room's volume. The manual notes that a very large size gives "a shifting, diffused delay effect" and a very small one "a highly colored, metallic feel". Size and decay are separate: a small room can still ring for a long time.

Input filters cut lows and highs before the signal reaches the reverb. Cutting low end going into a reverb is one of the simplest ways to keep a mix clear, because a booming tail under the kick and bass is rarely what you want.

Dry/Wet balances the untouched signal against the effect. Its right setting depends entirely on routing, which we come to below.

Types of reverb

You will see the same family names in nearly every plug-in. Ableton's Hybrid Reverb, for example, sorts its impulse responses into categories including Early Reflections, Real Places, Chambers and Large Rooms, Halls, Plates, Springs and Textures.

That device also shows the two ways reverbs are built:

• Convolution reverb "uses recordings of actual spaces (called impulse responses)". You hear a capture of a real hall, studio or object. The manual points out you can load recordings of anything, "from snare drums to garbage cans".
• Algorithmic reverb is, in the manual's words, "based purely on digital delay lines, and no samples are used". It is usually more flexible to tweak.

The names (hall, room, plate, spring) describe a sound, not a rule. Pick by ear: a short, bright room to glue a drum kit, a longer, darker hall for a ballad vocal, a spring or plate when you want something obviously "effect" rather than "space".

Pre-delay: the most useful knob you are ignoring

Pre-delay is the gap between the dry sound and the start of the reverb. Ableton defines it as "the delay time, in milliseconds, before the onset of the first early reflection", and adds that our sense of a room's size "depends partly on this delay". The manual gives 1 ms to 25 ms as typical for natural sounds.

Why it matters in practice: with zero pre-delay, the reverb starts on top of the consonants and transients, so a vocal can blur. Push the pre-delay up and the dry attack lands first, cleanly, with the space blooming just behind it. You get a big reverb that does not swallow the words.

Pre-delay is not the same as a delay effect. It shifts when the reverb starts. It does not create audible repeats on its own.

What delay does

A delay plays the sound back after a set time. The controls that matter, using Ableton's Delay device:

• Time or Sync. Set the delay in milliseconds, or in sync mode, where the manual says you set it "in sixteenth notes". Synced delays sit in the groove; free times are better for slap-back or for blurring a part off the grid. If your DAW does not sync, one beat in milliseconds is 60,000 divided by the BPM, so a quarter note at 120 BPM is 500 ms.
• Feedback "defines how much of each channel's output signal is fed back into its delay line input". Low feedback gives one or two repeats; high feedback gives a long trail that can build up.
• Ping Pong makes "the delay signal move back and forth between the left and right channels", which spreads a mono part across the stereo field.
• Filter. Ableton's Delay puts a band-pass filter before the delay line, and its Echo device offers high- and low-pass filters. Filtering repeats so they are darker or thinner than the original keeps them from competing with it.

Send or insert?

There are two ways to put any effect on a track.

Insert: the effect sits in the track's own chain and processes only that track. You blend it with Dry/Wet.

Send: you put the effect on a return (aux) track and feed it from as many tracks as you like. Ableton's mixing chapter says a Send control "determines how much of the track's output feeds the associated return track's input", and that placing an effect on a return "lets it receive audio from any number of tracks". On the return, the effect should output only the processed sound: the manual tells you to set Delay and Echo Dry/Wet to 100% "when using Delay in a return track". The dry signal is still coming through each original channel, so leaving the return partly dry just doubles it.

Ableton's returns also have a Pre/Post toggle that decides whether the send is taken before or after the track's mixer stage. The manual says the Pre setting lets you build "an auxiliary mix that is processed in the return track, independently of the main mix". In practice, post-fader is the normal choice for reverb and delay, because the effect follows the track when you turn it down. Pre-fader is useful when you want the effect to keep going, or to fade in, while the dry track drops away.

When to insert anyway

Insert when the effect is the part: a guitar running into a spring reverb, a synth with a dotted-eighth delay built into its tone, a heavily wet pad. Those are sounds, not spaces, and you would never want another track feeding them.

A simple starting setup

1. Create two returns: a short room or plate reverb and a longer hall, both 100% wet.
2. Create a third return with a tempo-synced delay, 100% wet, with some feedback and filtering on the repeats.
3. Cut lows going into all three.
4. Send each track a little to the short reverb so it sits in the same space. Use the long reverb and the delay for featured parts.
5. Add pre-delay on the vocal reverb until the words come back to the front.
6. Mute the returns and unmute them. If the mix falls apart without them, you are close. If you can clearly hear them as an effect when you did not mean to, turn the sends down.

Gain staging still applies to returns. Our floating-point gain staging guide explains why headroom matters even in a DAW that rarely clips internally, and our bedroom mix mistakes piece covers the wider list of things that cloud a home mix.

How we tested

This is a reference guide. Every control description and quote comes from Ableton's public Live manual, opened on 24 Oct 2026. The starting setup and the advice in "What we think" are our editorial opinion, not measurements.

What we think

Reverb and delay are where a lot of independent music loses its personality, not because artists use too little, but because they use a preset on every channel and each track ends up in a different imaginary room. Choosing a small number of shared spaces is an artistic decision, not a technical chore. It is the closest thing a bedroom producer has to picking the studio the record was made in.

We also think pre-delay and filtered repeats deserve more attention than any new reverb plug-in. Before you buy another, try the one you have on a return, at 100% wet, with the lows cut and a bit of pre-delay. Most of the "expensive" sound people chase is routing and restraint. Spend the money you save on a session player or a mastering engineer.

FAQ

Should Dry/Wet be 100% on a reverb return? Yes. The dry sound already comes from the original track. Ableton's manual gives this advice for Delay and Echo on returns, and the same logic applies to reverb.

How much pre-delay should I use? Ableton's manual gives 1 ms to 25 ms as typical for natural sounds. For vocals, try more and listen for the moment the words separate from the tail.

Post-fader or pre-fader sends? Post-fader for most mixing, so the effect follows the track. Pre-fader when you want the effect to continue independently of the track's fader.

Sources

• Ableton, Live Audio Effect Reference (Reverb, Hybrid Reverb, Delay, Echo), accessed 24 Oct 2026.
• Ableton, Mixing (return tracks and sends), accessed 24 Oct 2026.