Delay is, in essence, a very simple effect – it delays the audio so that you hear it later. When mixed with the original, you hear two versions of the audio – the original and the delayed version. Delay is often useful when set up on a send, similar to a reverb. Delay can sometimes be used instead of a reverb or in addition to reverb. Delays range from the very simple to very complex, but almost all have these two basic controls:
- Delay time – This sets the length of time that the audio is delayed. Delay times less than 100ms are short – useful for subtle doubling and thickening of instruments. Delay times between 100ms and 500ms are often heard as discrete echoes and a useful in adding a lush background texture. Delay times longer than 500ms are long – useful for special effects.
- Feedback – This feeds the delayed signal coming out of the delay back into the delay’s input. This adds more echoes, which makes the delayed sound thicker and causes the sound to take much longer to decay away. It’s somewhat analogous to the reverb time control on reverb processors.
Delay can sometimes be used as a substitute for reverb when you don’t want to add more diffusion to the mix. If the mix is supposed to be very dry and direct, delays can be a good way of adding depth and space without washing the sound out. Delays can also be useful for adding depth if a mix is already very diffuse (perhaps there’s already plenty of reverb and modulation).
Delays can also be used in addition to reverb. Using a delay?reverb chain (or reverb?delay, there’s no difference) on a send can very easily produce very lush ambience and sonic backdrops. Stereo delays (with a different delay time for left and right) are especially effective here. Use a feedback level of about 50% for extra lushness.
Stereo delays with short reverb times (less than 100ms) can be useful for making a sound wider and deeper. For foreground or percussion sounds this can often be distracting, but it works very well for background sustained parts such as synth pads or backing vocals.