US Vox E-Tuner "Add-on" Pitch Generator Circuit (1967-71)

Thomas Organ added an "E-Tuner" reference pitch generator (an electronic pitch pipe) to later V1121, V1122 and V1123 Buckingham amps, V1151, V1152 and V1153 Viscount amps, V1131, V1132 and V1133 Royal Guardsman heads and V1141, V1142 and V1143 Super Beatle/Beatle heads. Earlier amps equipped with the E-Tuner circuit utilized a rear panel mounted rotary switch to enable the feature. The rotary switch was replaced by a slide switch in later production. The auxiliary part of the circuit (shown at left) was mounted to the upper inside left corner of the head cabinet. The volume of E-Tuner was adjusted by the Bass channel volume control.

The Thomas Organ/Vox service manual stated that the E-Tuner circuit was "adjusted at the factory to a frequency of 323.628 cycles, the true pitch of the high "E" string on a six string guitar."

If a serviceman neglects to reconnect the E-Tuner to the preamp after service, the Bass channel will not function.


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