A digital delay emulates an analog tape-echo unit. A tape-echo is a special type of tape recording. It uses one head to record a signal and up to four heads to replay it. The delay time is set by the tape speed and the space between the heads. A digital delay essentially performs exactly the same function as a tape-echo, but offers more refinements and adjustments than its mechanical counterpart. A delay essentially creates an echo, although you can often use delays to create more complex time-based effects. The source signal is delayed so that it is heard later than it actually occurred.