A delay usually works by, figuratively, putting audio in one end of a pipe and grabbing it again when it comes out the other. That pipe usually consists of cells such as digital memory locations or “bucket brigade” (BBD) analog circuits that hold snapshots of your audio. The more of these cells you have, the longer the delay is as the sound snapshots propagate along that pipe. (In a digital delay, the samples are not passed from location to location as with a BBD; the in and out points are constantly moved instead – but it’s a good analogy.) Of course, the sample rate at which the snapshots are passed along or read out also affects the delay time.
A multi-tap delay says “Why wait until the audio snapshots go all the way through the pipe? Let’s grab it when it’s only part way through the pipe.” Those points where it’s prematurely grabbed are the “taps” – kind of like additional water taps added along a long pipe. This allows you to get multiple delay times out of a single delay line. The taps might be spaced at musical subdivisions, such as halves or quarters of the overall delay time; they may be user-adjustable so you can create “random” delays akin to the slap back from multiple hard surfaces – this is a way to simulate the start of reverberation.
Some multi-tap delay lines have built-in mixers that combine the outputs of the various taps; some (such as the Sputnik Four-Tap Delay) just present them on output jacks for you to patch as you wish – such as to a mixer, back into the input for feedback, etc.
« Back to Glossary Index