VOX SOLID STATE AMP CIRCUIT DIAGRAMS (Schematics)
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February 2021. The page is in the process of being tidied up and expanded, so do check back from time to time.
JENNINGS MUSICAL INDUSTRIES AMPS - the Mark I circuits
Virtuoso Power section - OS132
The JMI schematic - a copy of a old Xerox but sharp nonetheless. Click the thumbnail above for a larger image.
A modern redrawn version of the above.
Conqueror and Dynamic Bass power section - OS133
The JMI circuit diagram.
A redrawn version - power ratings of a number of resistors not included.
Defiant and Foundation Bass power section - OS134
Supreme and Super Foundation Bass power section - OS135
Virtuoso, Conqueror, Defiant and Supreme preamp - OS136
Drawn by Chris Devine.
Dynamic, Foundation and Super Foundation Bass preamp - OS137
Drawn by Pete Kappa.
A copy of a copy of the JMI sheet, probably from "Modern Music in Dudley. The panel giving the date of redaction and changes is missing.
Virtuoso preamp without reverb - OS145
Forthcoming. The preamp with reverb is OS136, above.
Wah Wah pedal (The "Grey Wah") - OS158
The BC150 transistors were later changed to 2N3707 as production gathered pace. The circuit boards of the earliest pedals were glooped with a black adhesive cement to prevent copying. See this page.
The Thomas Organ "preliminary schematic" for its pedal, April 1967, incorporated in the Accessories Service Manual. Note the differences around the inductor.
LATER AMPS (1969-1972) - the Mark II / Mark III schematics
In the main, the power sections of the guitar and bass amps follow the older JMI schematics. However, in late 1969 the standby circuit was removed.
OS/184, which bears the name of Vox Sound Limited, was actually taken over from the Vox Sound Equipment Limited Mark II schematic. Note the register of changes, top left, and the signs of erasures in the panel, lower left - which one can see also lower left in OS/185.
The list of changes from OS/184. In terms of the preamp, "Mark II" was the new six-position MRB.
The lower left panel of OS/184, bearing signs of erasure and updating.
Conqueror, Defiant and Supreme preamp - OS/184
Click the thumbnail above for a larger image.
Dynamic Bass, Foundation and Super Foundation Bass preamp - OS/185
The Public Address and All-Purpose Amplifiers - 1968-1973
The "Vox Sound Equipment Limited" schematic for the PA100SS mark 1 is OS/176; the PA50SS is OS/177.
OS/176. A good complete copy of the schematic, including the schedules of changes at top left.
OS/177 for the PA50 SS. The earliest visible change at top left is 2th November 1968 (though another clearly preceded it).
Vox Midas 100 - OS/208
Redrawn and clarified by Pete Kappa.
The reverb circuit.
Layout of the reverb circuit.
A copy of a copy of the "Vox Sound Limited" sheet from "Modern Music" in Dudley. Some portions are good.
VSL Slave Driver - sheet number unknown
Circuit diagrams for the amplifier drawn by Pete Kappa from serial number 1001 are available on this page.