Delay

The Echoplex was one of the first portable analogue delay units, it was used a lot by rock guitarists such as Brian May. 

The unit would record the signal on magnetic tape as it was being played and play it back. Delay time would be adjusted by moving the playback head. Feedback could be adjusted by feeding the tape back through the machine. The tape would degrade in quality, resulting in a lack of high-frequency content. This created a warm sound that became synonymous with analogue delay and is commonly emulated by digital models. 

Later devices made use of bucket brigade chips instead of tape. While these were more convenient and reliable, they were substantially noisier. 

Create by Sam Phillips at Sun Studios in Memphis TN, this form of delay had a delay time of 80-200ms to create a percussive effect, set at a high level so it was obvious in the mix. 

Used a lot on 50s rock n roll. 

Uses digital memory to store the recorded signal. 

The digitisation of the signal allows for more creative freedom than was first possible with analogue delay units.

Delay time could now be set to match the tempo of the music. 

Multi-tap delay allows the user to set several different delay times in one effect. 

When first invented, delay was mostly used to thicken and add warmth to a signal. 

Due to the creative freedom that accompanies virtual modelling, we can now use delay to achieve a variety of effects.

Automatic double tracking: adding minor detuning to a signal and setting an almost instant delay time to create the effect of a double track.

Other effects like phasers and chorus were born out of the new uses of digital delay.