The advent of electrical amplification in the mid twentieth century brought with it a desire to augment its dry, sometimes harsh amplified sounds with reverberation. This was mainly achieved through the use of reverberation chambers, metal plates, and spring reverbs for portability. These technologies provide shimmering, hall-type echoes, but cannot produce sharp early reflections or clear echo repeats.
Magnetic tape, which became widely available in the sixties, made it possible to emulate clear, well-defined echoes, that could be repeated numerous times, by using a combination of read and write heads to physically delay the signal along a tape. For years, tape and other magnetic supports were the only available technology widely available to achieve this. Thousands of tape delay machines were built throughout the sixties, seventies and early eighties. Such devices could be seen on stage and in studios all over the world.