Delay effect started out as a tape based effect, with products like the Echoplex and Roland RE-201 Space Echo being some of the more popular products back in the ‘analogue’ days. These tape based delays used a tape loop on which the incoming signal would be recorded, and then played back some time after, creating the delay effect. They could feed the recorded signal back in again to create what is commonly called the echo effect, which was simply a delay with multiple repeats. The problem with these tape based delays however was the fact that the tape would eventually wear out, and each time the signal was fed back in the sound would deteriorate a little causing the top end to roll off.
When digital signal processing came along, it would solve the ‘problem’ of tape based delays as there was nothing to wear out, and the signal did not degenerate with repeated echoes. These early digital delays of course had their own issues, primarily early digital did not have wide bandwidth so they inherently sounded less than pristine when compared to the incoming signal. However the bigger problem was delay time, which was limited by the amount of what was then, very expensive memory chips. As time went on however, digital became cheaper, memory chips became more affordable and digital delays came into their own. These newer models offered pristine delays with full bandwidth and plenty of delay time on offer.
Products like the very popular AMS DMX 15-80S and much later the Yamaha D5000 which is so dearly loved by Bob Clearmountain, took digital delay into the realm of perfection. But then a funny thing happened…Suddenly everyone missed the warm rolled off top end that tape based delays offered, and so today we have delay plugins that emulate these classic old tape delays systems, as well as offering the pristine delay that quality digital can provide. Like all things digital however, certain older hardware based delays still sit front and centre in the minds of many engineers. Products like the Lexicon PCM42 and the TC Electronics TC-2290 are heal in such high regard and still command serious money on the used market today.