jan 1, 1939 - spring reverb

Description:

Laurens Hammond was granted a patent on a spring-based mechanical reverberation system in 1939 
A spring reverb system uses a transducer at one end of a spring and a pickup at the other, similar to those used in plate reverbs, to create and capture vibrations within a metal spring. Guitar amps frequently incorporate spring reverbs due to their compact construction and low cost. 

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