The Fender Reverb Unit (6G15) was a

vacuum tube A vacuum tube, electron tube, valve (British usage), or tube (North America), is a device that controls electric current flow in a high vacuum between electrodes to which an electric voltage, potential difference has been applied. The type kn ...

, spring

reverb Reverberation (also known as reverb), in acoustics, is a persistence of sound, after a sound is produced. Reverberation is created when a sound or signal is reflected causing numerous reflections to build up and then decay as the sound is abso ...

-equipped

effects unit An effects unit or effects pedal is an electronic device that alters the sound of a musical instrument or other audio source through audio signal processing. Common effects include distortion/overdrive, often used with electric guitar in el ...

made by Fender. The Reverb Unit was originally introduced in 1961. It was discontinued in 1966 and was replaced by a solid-state model, the FR1000. The unit features three controls: Dwell, Mixer and Tone and includes a 12AT7 tube as a

preamplifier A preamplifier, also known as a preamp, is an electronic amplifier that converts a weak electrical signal into an output signal strong enough to be noise-tolerant and strong enough for further processing, or for sending to a power amplifier an ...

; a 6K6 tube as the reverb driver; and a 12AX7 as the reverb recovery tube. The rectifier is a diode-type solid state unit. The circuit board, like Fender's

Brownface Brownface is a social phenomenon in which a white or light-skinned person attempts to portray themselves as a "brown" person of color, but less overtly and with a lighter complexion than traditional blackface. This may include mimicry of Midd ...

Blackface Blackface is a form of theatrical makeup used predominantly by non-Black people to portray a caricature of a Black person. In the United States, the practice became common during the 19th century and contributed to the spread of racial stereo ...

and

Silverface Fender amplifiers are a series of electric instrument amplifiers produced by the Fender Musical Instruments Corporation. The first guitar amplifiers attributed to Leo Fender were manufactured by the K&F Manufacturing Corporation (K&F) betwe ...

amplifiers is an eyelet board and the unit its completely hand wired. The spring reverb “tank” is mounted on the interior side of the front baffle in a vertical position. Tanks were supplied by Gibbs and Accutronics in the original version. The vertically mounted tank should be a 4AB3C1C (last letter in Accutronics model designation indicates tank orientation) but most actually shipped with 4AB3C1B tanks which are designed for horizontal mounting; these are the same ones found in the Fender combo amps where it is mounted on the floor in a horizontal configuration. Physically, the unit looks like a small amplifier head and since the early 1960s the unit has become synonymous with surf music.

1976–1978

The "Tube Reverb" was reintroduced in 1976 with a silver control panel ("Silverface"). It was discontinued in 1978.Teagle, J. and Sprung, J.: ''Fender Amps: The First Fifty Years''. This reissue differs significantly from the original 6G15 circuit. The unit has 4 tubes: V1 (Input/preamplifier, a 12AX7 as opposed to a 12AT7 in the earlier three-tube version), V2 (reverb driver, a

6V6 The 6V6 is a beam-power tetrode vacuum tube. The first of this family of tubes to be introduced was the 6V6G by Ken-Rad Tube & Lamp Corporation in late 1936, with the availability by December of both Ken-Rad and Raytheon 6V6G tubes announced. ...

as opposed to a 6K6 in the original), V3 (reverb recovery, a 12AX7), and V4 (a buffer stage, using another 12AX7). V4 acts to reduce changes in output impedance when the wet-dry mix is varied, ameliorating the “tone suck” (loss of volume and some high frequency signal) seen with the original and later reissue 3 tube versions. Further, the 6V6 driver was wired with fixed bias (as opposed to cathode biased in the 6G15 circuit) and in triode mode (with plate and grid connected).

Reissue (1994-2016)

A reissue of the original tube reverb was introduced in 1994 and manufactured through 2016. Some changes in the circuit were made to accommodate a 6V6 reverb driver tube, replacing the obsolete 6K6. Reissues also have two printed circuit boards (potentiometers are mounted on the smaller of the two) and a mix of hand wiring and spade connectors. It is available with

white White is the lightest color and is achromatic (having no hue). It is the color of objects such as snow, chalk, and milk, and is the opposite of black. White objects fully reflect and scatter all the visible wavelengths of light. White on ...

black Black is a color which results from the absence or complete absorption of visible light. It is an achromatic color, without hue, like white and grey. It is often used symbolically or figuratively to represent darkness. Black and white have o ...

brown Brown is a color. It can be considered a composite color, but it is mainly a darker shade of orange. In the CMYK color model used in printing or painting, brown is usually made by combining the colors orange and black. In the RGB color model used ...

tolex. Fender also now makes a tweed-covered Reverb Unit to match its Tweed amplifiers of the 1950s.

References

Fender amplifiers Valve amplifiers {{guitar-stub