History of Echo Machine

An echo machine is the early name for a sound processing device used with electronic instruments to repeat the sound and produce a simulated echo. The device was popular with guitarists and was used by Jimmy Page and Syd Barrett among others. Nowadays it would normally be called a Delay or Echo.

Early versions (1970) were analog and consisted of one or more transducers on one end, a coil spring of 1-2 feet in length, and transducers on the other end, each connected to a separate spring. The transducer turns the audio signal into mechanical vibrations which travel down the spring experiencing a delay before they arrive at the transducer at the other end. At that point, the sound is reproduced and fed back into the amplifier as an echo. The size and tension of the springs creates different delays, and could be applied to any audio source. These devices were inexpensive, hobbyist grade, and sometimes sold in kit form so every garage band could have one.

Later, and for more money and with more professionalism, echo machines were made with tape recorders where the tape speed and distance between record and playback head determined the delay for the echo.(Wikipedia)