Vox PA units

For Vox 50 watt PA amplifiers, , and for column speakers and so on, .


The earliest Vox Public Address amplifiers were the sloping-front "Metal Clads", available in four power outputs: 15, 30, 50 and 100 watts.

Above, a detail from the "Precision in Sound" newspaper catalogue from 1964 illustrating the Metal Clad public address amplifiers and the Linesource 40 column speakers.

Above, the blurb from the review of the British Musical Instrument Industries Trade Fair, August 1964, published in "Beat Instrumental" magazine, October of that year, setting out the rationale of the PA amplifiers - presumably springing from what Denney and Reg Clark (JMI Sales Manager) had said at the Fair. The text straddles an unrelated picture which has been omitted.


Dick Denney at the British Musical Instruments (Association of Musical Instrument Industries - AMII) Trade Fair, Russell Hotel, London, said to be 1965 (23rd - 27th August). A six-input PA to his left. In the picture immediately above, two PA amps are visible. Strange to say though, this looks more like 1964 than 1965.

Item from the review published in "Beat Instrumental" magazine, October 1965, of the British Musical Instrument Trade Fair at the Russell Hotel, London, August 1965. The new style of Vox PA amplifiers unveiled, evidently regarded as being a stop-gap as far as cosmetics were concerned.

A detail from a catalogue of 1965

In 1965 The Who evidently used a second generation 100 watter - a "metal clad" but without a sloping front.

A detail from a shot of The Who on stage in mid 1965 - a MC100 on a chair. Note that its front is flat and there is no handle on top.

Surviving amps from 1964 - 1965

PA100 type 1 - transistor preamp (?)

Meter on front

The first type of MC100/6 - pressed steel case, louvres and handles on the sides. The VOX logo is of the "square letter" variety, as found on the bridge cover of Vox guitars.

An early unit - probably 1965. Note the presence of XLR sockets rather than the jack plugs of the advert.

Surviving amps from 1966 - 1967

The new range of 50W, 100W and 150W public address amplifiers was put into production for Vox by . Most had transistor preamps. The power sections remained all valve however. The blue/grey and white livery was applied also to the growing array of , and other devices.

In terms of electronics, a notable feature of the new 100W PA amps is the provision of individual bias controls for the output valves, similar to those of the Vox UL 4120 and UL 7120, which were also assembled (and part designed) by Triumph.

PA100 type 2 - transistor preamp

Meter on front, two speaker outlets

Serial number unknown - currently in the UK

Currently in the UK, a rare PA 100 with power meter. The transistor preamp looks good and intact; the power section does require a little attention though. Two of the four EL34s were replaced at some point by 6L6s.

June 2013 - the amp now beautifully restored and in full working order. Thanks to Mick for the pictures.

PA100 type 3 - transistor preamp

Meter on front, four speaker outlets

Serial number unknown - currently in the UK

Sold on ebay in September 2014. Box and power meter missing, but great condition. Assembled by Vox for Triumph Electronics. The preamp, as above and below, is solid state. Power section is all valve with individual bias controls for the EL34s.

The transformers were evidently supplied by Drake - note the format of the part numbers. Mains: 1204-66B. Choke: 352-169. Output: 1202-111.

In terms of date, one of the Hunts caps has the date code "NYW" = first week of 1966. For more on the Hunts dating system, on the Vox AC50 website. That one of the pots has the code "AO" = January 1967, indicates however that the amp was probably produced in the first half or perhaps first third of that year.

The same amp as above, cleaned up and with the addition of a power meter.

Serial number unknown - currently in the UK

Sold on ebay.uk in early 2014. Just the power amp chassis, but in good condition. This is a larger (wider) unit, as above, with four 1/4" jack outputs rather than paired round Bulgins.

Serial number unknown - currently in the USA

Again, four 1/4" jack sockets for the speakers. The power cable now hard-wired, feeding through a hole next to the Bulgin. Thanks to Robert for the pictures.

PA100 type 4 - valve preamp and power amp

Redesigned box, two speaker outputs

Image from the Vox catalogue of 1966

The band Styler's Musical Express playing at the Lion Hotel, Singapore - note on the centre of the riser a metal-clad PA much as the 100 watter below.

The Yardbirds, April 13th, 1967.

Serial number unknown - currently in the UK

A monster from 1966 in good physical and cosmetic condition. Many elements are similar to the 7-series amps - tagboards with eyelets (instead of hooks), Mustard capacitors, insulated stand-offs on the chassis, and individual controls for the output valves' bias on the back panel. The EL34s are the original ones, with Mullard date codes B5G2 = Blackburn Factory, 1965, 2nd week July.

1967 - full solid state

In early 1967 the plan was to replace these amps with a new all solid state version, part of the line of all solid state guitar amps (the Conqueror, Defiant, Supreme, and so on):

Above, the amps in the solid state catalogue of early to mid 1967. No surviving examples have hitherto been seen however. For further info on the solid state range of amps, see the . A synopsis of some of the material can also be .

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