The Vox PA50 - 1966 to 1968

Details relating to earlier Vox PA50 units (1964 and 1965) are . The amplifiers below are of a new design, first shown in public at the "British Musical Instrument Industries" Trade Fair at the Russell Hotel, late August 1965. A page on the Fair .

PA equipment was important to JMI, more important perhaps than has normally been admitted. Various elements of the story are .

A page from "Beacon", July 1967, the Journal of the Royston Group of Companies - the group that owned JMI. Pictured is Cyril Windiate, secretary to Tom Jennings and later Managing Director of both JMI and VSEL. The piece extols the virtues of a PA system set up by Vox.

The two principal later types of PA50 (MC50) - all valve and "hybrid" (solid state preamp, valve power section) - were produced for JMI, as before, by Triumph Electronics in Purley. Triumph also produced the smaller and larger units in the range - the PA15, PA30 and PA100. Transformers were specially made for these amps by Drake (which also produced transformers for Marshall). Woden occasionally made the chokes.

All-valve PA50s generally had four inputs: - three for microphone, one for music. PA50s with solid state preamps have six: - five for microphone, one for music.

The format of back panels varied considerably. Some amps were provided with 100v line output; others simply had Bulgin or jack sockets. No circuit diagram has so far come to light.

The serial numbers of the PA amplifiers continued to run ran as part of the same series as the guitar/bass amps.

References to PA units in music paper small ads are being collected .

Valve preamps - 1966 to 1968

Serial number unknown

  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50

The preamp valves date to 1965. However, one of the pots has the code LN = December 1966; and another FN = June 1966; so the amp was probably produced for Vox early in 1967 by the Triumph works. A few repairs here and there, and fairly scuffed on the outside, but otherwise in good condition. The transformers were made by Drake and have codes that will be familiar to those who know Marshall amps: output transformer is 784-125; power transformer is 1202-112A and the choke 352-169. From the sticker on the front, the amp seems to have been used somewhere in Northern Ireland.

Serial number unknown

  • PA50
  • PA50
  • PA50

Sold on ebay a few years ago. Unfortunately the serial number on the plate on the amp's underside was not recorded.

Serial number unknown

  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50

Formerly in Canada, perhaps currently still in North America. Thanks to Will for the pictures. Note the valve sockets, supported on brackets at a level lower than the rest of the chassis, presumably to obtain as much clearance for the EL34s as possible. A similar solution was applied to the Beatles' 7120 amps, also made by Triumph. The output transformer of this PA, which provides a 100V line for hall or field speakers, is absolutely massive. No maker's stamp is visible on the OT and PT, but they may be Wodens. Note on the underside of the latter the varnished/waxed cloth wrapping - identical to the wrappings in the Woden transformers in AC30s, AC80/100s and so on.

Just to note, the choke certainly is Woden. There is no date code (unusual for Woden), simply the PA model number - MC/50/3, ie. a Vox MC50 mark 3.

Serial number unknown

Sold in Vancouver in 2020. Perhaps the same amp as above.

Solid state preamps - 1966 to 1968

The meter on the front panel enables the user to read off the bias of the EL34s along with the working power output, the various functions of the meter being accessible via the control knob to its left. Various iterations of the Vox MC100 were similarly equipped (some from the autumn of 1964).

Serial number 7597

  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50
  • PA50

Sold a few years ago. For some time in Spain. The date codes on the bias pots appear to be "HM" = August 1965.

Serial number unknown

  • PA50
  • PA50
  • PA50

Currently in the UK.

Back to the page on Vox PA50s, 1964 to 1966.