The initial spring reverbs emerged in the 1950s, developed by Hammond primarily for their organs.

In 1961, Fender began crafting their own Reverbation units, utilizing spring units purchased from Hammond.

Initially marketed as an external effect unit, it was integrated into a combo amp with the release of the Fender Vibroverb in 1963. However, it remained available for separate purchase until 1966, was then discontinued, only to be reintroduced from 1976 to 1978.

Specifications:

Circuit : 6G15
Input/output: In, Out & Footswitch connector (no footswitch included)
Settings: Dwell, Mixer, Tone
Transformers : original dated 606325
Reverb pring : original dated 6339
Tube charte date : ML (dec 1963)
Serial: R04728