The delay time can range from several milliseconds to several seconds. Figure 1 presents the basic delay in a flow-graph form. This only produces a single copy of the input, and thus is often referred to as an echo device. Sound Set 1 presents a variety of delay settings to give you a feel for delay times. Delays applied to a pulse-like sound .You will first hear the pulse, then the same pulse processed with a 60 ms.
Delays are very useful for filling out an instrument's sound.
Playing through a delay unit with a short echo, say 50 to 100 milliseconds, creates a doubling effect, as though two instruments were being played in unison. An example of this quality is shown in Sound Set 2. Using several delays together with feedback can be used to create a reverb-like sound, though a typical reverb unit will create a more complex sound pattern. As you increase delay times beyond 100 milliseconds or so, the delay no longer a subtle effect. One interesting possibility is to match the delay time to the tempo of a song so that the delayed copies of the sound fall on the beat.