A delay line which works by converting the incoming signal to a digital form and then writing it into a memory area, which is read out some time later, per the desired delay time. Varying the delay time is accomplished by changing the number of memory words used; adding more memory increases the delay time. The digital sample rate, and therefore the available bandwidth, remains constant (contrast with the analog delay).

Compared to analog delays, digital delays are generally quiet (except for some very old models), and long delay times can be achieved at a modest cost.