An electromechanical effects device that uses springs to simulate natural room or hall reverberation. Spring reverbs work basically like plate reverb systems, but are muchk smaller and produce an inferior effect. A transducer sets up vibrations in the spring which rattles back and forth, extracted by a pick-up at the other end. The character of a particular spring reverb unit is fixed (other than wet/dry balance), but can be optimized for the sound source at the design stage by careful choice of the number, length, diameter, and compliance of the spring(s). Also called a spring-line reverb.