Reverb is a tool that’s easily recognised and often overused. Reverb is one of the best tools for enhancing the sense of space and depth in a mix. It works by adding a wash of sound – called the tail – directly after the original sound. This tail usually simulates the kind of sound heard in a large hall. There are many different kinds of reverb – ranging from simulations of small and large physical spaces, to electromechanical reverbs (such as springs and plates), to fantasy reverbs (such as gated reverbs and reverse reverbs).
Reverb is most commonly used on a ‘send’. This is a special kind of mixer channel. Instead of receiving its input audio from the multitrack recording, it receives its signal from the other mixer channels. The amount (level) from each channel is controlled by the ‘send amount’ for each channel. This is a good way to use reverb because it allows for one reverb processor to add its reverberation tail to many channels (sends often aren’t appropriate for channel EQ or compression).
If you’re getting started with reverb, start with a simple hall reverb. Set it up on a send bus, and choose a basic reverb preset (usually the default start-up preset will be a good way to begin). Then send a little bit from each channel to the reverb. A good rule of thumb is to add just enough reverb that you can hear it. Background sounds will normally need more reverb than foreground sounds, and sustained sounds will usually need more reverb than percussive sounds.
Mute the reverb channel and compare the mix with and without reverb. It should sound like the same mix, with the reverb adding subtle space and depth. If the reverb is overpowering, simply reduce the send levels of the more prominent instruments.
If you want to customise the sound of the reverb, you can tailor it to the sound of the mix you’re working on. Each reverb is different, but there are often some common controls:
- Length (Time) – This is the most obvious control. It allows you to change the length of the
- reverb tail. Longer reverbs work better for music that’s slow, sparse or abstract. Shorter reverbs are the opposite – they work better for music that is fast, dense or acoustic. Too short and the reverb won’t have much effect. Too long and it’ll make the mix messy and indistinct.
- Size – Size often works with length. While length adjusts how long the reverb tail is heard, size changes the apparent depth of the reverb. It works similarly to the the size of a physical space – a small room will sound tight and intimate and a larger room or hall will sound deep and spacious. Like length, the right setting will depend on the music. Too small and the reverb won’t have much effect, too large and it’ll sound indistinct.
- High frequency (HF) damping – This affects the way the high frequencies are processed by the reverb. HF damping reduces the high frequencies being reverberated. Low levels of HF damping will make the reverb sound very ‘live’ – like an empty hall with a lot of hard surfaces. High levels of HF damping will make the reverb sound warmer. Too little HF damping will make the reverb sound airy and obvious. Too much HF damping will make the reverb sound dead or ‘damp’. As with the other controls, the best setting will often be somewhere in the middle, depending on the sound of the mix.
- Pre-delay – This control inserts a delay before the reverb, making it sound later after the original sound. It can be used to increase the apparent size of the reverb. Because pre- delay separates the reverb from the original sound, it can also add clarity to particularly reverberant mix. This is most useful for vocal-heavy mixes because it allows the vocal to be quite reverberant without reducing its intelligibility
When adjusting reverb parameters, it’s often helpful to solo a single sound. Usually the lead vocal or a sparse drum/percussion part will let you hear the reverb most clearly.