2. Electromechanical approaches

Echo chambers

As early as the 1920s, studios were equipped with echo chambers, reverberant rooms in which a dry signal is diffused by a loudspeaker, then re-recorded by microphones. The wet signal is then added to the dry signal. The characteristics of the echo chamber (generally built without parallel surfaces to avoid standing waves and undesirable flutter echo phenomena), the positions of the microphones and loudspeaker (generally in a corner, so as to excite a large number of modes) and the addition of drapes or absorbent materials ensure a degree of reverberation control. This approach produces natural reverberation, but is expensive, cumbersome and inflexible.

Spring and plate reverberators

To overcome these drawbacks, various electromechanical devices were designed from the...