Reverb is an effect whereby the sound produced by an amplifier is made to reverberate. Reverberation is the result of many signal reflections on different surfaces building up and then decaying as the sounds are absorbed by different surfaces and space. The resultant
effect augments the source sound in that it provides space, depth and a sense of environment e.g. small room, hall, cave, cathedral etc.
Laurens Hammond of Hammond organs popularised the use of reverberation devices through his church organs in the 1940s and 1950s. Reverb first made their debut in Fender amps in 1961 in the form of a spring unit (hence the name spring reverb).
There are a number of reverb types, other than spring reverb, in use today which produce the reverberation effect albeit slightly different.
Spring reverb makes use of input transducer to pass a signal through a number of springs to generate signal reflections. An output transducer then changes the magnetic fields generated by the moving springs back to an output signal.
Plate reverb is produced by suspending a steel plate under tension with springs, a transducer in the middle of that plate passing the input signal causing vibrations and small pickups located on the converting vibrations back to output signal.
Digital reverb makes use of algorithms to emulate different types of natural reverb. It cannot perfectly recreate the natural reverb but the results are very convincing. The benefit of digital reverb is that it can be used in many applications and doesn't require reverb rooms or electromechanical equipment to reproduce the effect.
The table below provides some details of reverb.