The
delay effect is a
sound reinforcement device used by
musicians and
sound engineers to add an
echo to sound
channels. It just repeats its input
signal one to infinite times in a (time)
interval of some
milliseconds.
Although in my opinion the delay effect for PAs (Public Address systems) should be used only sporadically (because it's quite a strong effect and most of the time it just adds noise to your signal), it's important to know how to set the parameters well. The following are some ways to achieve this I have learned by doing.
The delay time must be synchronised with the band's drum. On some effect processors you can do this by tapping twice on a button (this function is more often on old processors — don't ask me why) or by directly entering the song's bpm (beats per minute), if you know it. But frequently you'll have to know the actual delay time in seconds(s) or milliseconds(ms). This delay time t can be calculated with the formula below:
60 * TS / bpm = t
TS beeing the time signature fraction's (like 3/4, 4/4, 6/8, etc.) numerator (3, 4, 6, resp.) and bpm beeing beats per minute; e.g. for a 3/4 piece at 90 bpm the delay between beats would be:
60 * 3 / 90 = 2s = 2000ms
It might be useful to save this value as a preset, but often you will need to adjust it during performance (rock/pop musicians seldom use metronomes on stage). Obiously this is done by comparing the PFLed (solo) input and output signals to the delay EFX.
See also 'stereo delay'.