1964 Fender reverb unit. This is one of the later models, sporting black tolex and white cupcake knobs.  FULLY SERVICED AND READY TO ROCK!  Please see service notes.  MAKE AN OFFER!  Also listing a matching bandmaster amp and cab be sure to check my other listings.  

When I think of surf guitar music, from Dick Dale to the Beach Boys, the first sound that echoes through my mind is spring reverb. The deep, drippy, swampy, dimensional sound of a spring reverb is essential for creating those crashing, wet waves of guitar tone.

Spring reverb was invented by Laurens Hammond in the 1930s, and he officially applied for the patent in 1939. Hammond wanted to use spring reverb in his Hammond organs to recreate the depth and echo of the grand pipe organs that filled up large churches and concert halls. As electrified instruments became a common fixture, many folks were using Hammond organs in smaller churches and at home—and desperately needed to add more dimension to fill up those rooms.

Spring reverb didn’t appear in guitar amplifiers until the early 1960s. The Ampeg Reverberocket, introduced in 1961, was the first combo amp to include it, arriving around the same time as Fender’s early stand-alone reverb units.

The spring reverb effect was not commonly on-board in guitar amps until the mid-60s. Until then, the separate spring reverb unit was sold as an add-on. Fender dominated the market at that time with the 6G15 unit, which was first sold as early as 1961. This was the heyday for surf guitar, and the reverb units provided that extra layer of deep, drippy echo that is an essential dimension of surf guitar music.

The Fender Reverb unit was included in the blonde, brown, and black tolex eras of the Fender product line. The Reverb unit was treated like an effects pedal, where the guitar would plug into the input of the unit, and the output would plug into the amp. Fender first included reverb in the 1963 Vibroverb, which then became a standard built-in effect for many of their amps by the mid-1960s.

The onboard reverb in Fender amplifiers is an integral part of their legacy. It is a lush-sounding effect, but the 6G15 adds even more versatility to the circuit. The user can adjust the dwell (the overall springiness of the effect), how much wet signal is applied to the mix, and the tone of the reverb itself. By manipulating the tone control, the user can lean towards a bright or a dark reverb sound. All these factors highlight the stand-alone reverb unit’s ability to outshine the single reverb level control in the on-board reverb circuits.

Regardless of the nature of the reverb circuit, the effect is popular to simulate a moody sense of dimension. Analog effects are soulful and life-like, as they manipulate the signal to add or subtract elements of space and time. Add the 6G15 reverb unit to any rig, and it will come alive.