LARGE BOX AC50s - late 1964 to mid 1965

Valve rectified amps, part 2

Assembled by Triumph Electronics

The amps on this page, all valve rectified, were assembled for Vox by Triumph Electronics in Purley in the second half of 1964. For more on Triumph, .

Serial numbers, as mentioned on the , are not a reliable guide to relative date. Finished chassis, boxes and serial plates were brought together in a fairly random way at JMI in Dartford - see the section on "manufacture" .

Unlike the AC50s made later on at the Burndept factory in Erith, Triumph-made amps do not have numbers stamped on the flat of the aluminium chassis underneath the input jacks.

Two new-style voltage selectors come in (the old type of selector had a removable plug). First, a selector with a slot in it (probably the width of an old penny) as found also in certain AC10s. This was eventually superceded by the more conventional dome voltage selector.

The feeling is that Triumph used up its box of slot selectors first - perhaps 50 or so - and then moved on to the new boxes of dome selectors.

Most of the details noted on the hold good for the amps pictured below, with one principal exception: speaker output sockets are now rectangular Cannon XLRs rather than 1/4" jack.

Mains cables are still hard wired - there is no socket on the back panel.

Shelf-mounted reverb units (factory-fitted) occasionally occur.

Serial numbers were hand-stamped up to and presumably a little beyond serial number 1746. Machine-stamped numbers come in at some point before number 1763.

The pencil signatures of the checkers who signed the AC50s off can regularly be seen on the underside of chassis - "DE" is Dave Earp, who worked for the company in the mid 1960s. "K" at present is unknown. The checked bias voltage was also noted in pencil.

In terms of speaker cabs, AC50 no. 1607 below (dome voltage selector) has its original 2 x 12" enclosure for guitar (containing two Celestion alnico T1088s sprayed silver/poly grey and one Midax horn). A good number of amps figure with Foundation Bass cabs - probably the ones with which they were originally paired.

Below, a register of amps. If anyone knows of others that have not yet been included, do let me know.

Vox AC50 slot voltage selector

Serial number 1462 - currently in the UK

Sold on in April 2012. Replaced grille cloth. Hand-stamped serial number. Seller noted that the outputs were jack sockets rather than XLRs.

Serial number unknown - whereabouts unknown

Black escutcheon panel for the XLR sockets.

Serial number unknown - whereabouts unknown

Original XLR connectors in place on an early-style black plate. Note that no mains connector was provided - the lead is hard wired, as in the case of no. 1678 below. Also note that the fixing on the top edge of the back panel is centred.


Serial number 1723 - currently in the UK

Serial number plate hand stamped. Needing a little bit of revamping, but electronically all there - nothing evidently replaced in the preamp.

Serial number 1727 - currently in the UK

Sold on in Jan. 2013. Good overall condition; replaced handle. The output plate is new-style (ie. not the early black type); white warning plaque; slot rotary selector. Hand-stamped serial number. Mustard capacitors have the code "D3" = last quarter of 1963. One of the Hunts caps in the preamp has the code "HNT" = 27th week of 1964 = August '64. One of the Hunts bias caps has "HDT" = 28th week of 1964. The bass pot of the normal channel bears the code "GL" = July 1964. Note that serial number 1725 has the newer domed voltage selector.

Serial number 1729 - currently in the UK

Missing its voltage selector. Serial number plate fully hand stamped. The latest discernible date code in the preamp is "A4N" on one of the mustard caps = 1st quarter of 1964. But the amp is likely to have been made in the third quarter of the year.

Serial number 1766 - currently in the USA?

  • Vox AC50, large box, serial number 1766
  • Vox AC50, large box, serial number 1766
  • Vox AC50, large box, serial number 1766
  • Vox AC50, large box, serial number 1766

Mains lead hard wired. Original XLR output sockets in place. Possibly a slot voltage selector, though hard to be absolutely sure from the small pictures from ebay.

Serial number 1800 - currently in the UK

Sold on ebay in late 2014. Accompanied by a solid state Foundation Bass cab. Hand stamped "AC50"; machine-stamped serial number.

Serial number 1847 - currently in Japan

1/4 inch jack sockets instead of XLR connectors - apparently original. Note that an amp on the previous page (with a link voltage selector) has an output panel of the same sort (white circular surrounds for the jack sockets). Machine-stamped serial number. Images originally .

Serial number 1852 - currently in Europe

Slot voltage selector. The serial number is machine stamped on the plate, but the designation "AC50" is hand stamped. Latest code visible on the mustard caps is B64 = second quarter of 1964. One of the pots (normal channel, treble) has the code "BL" = February 1964. One of the Hunts caps on the bias board has the code "HDT" = 28th week of 1964 = July '64. The main preamp filter cap on the left has "INT" = 37th week of 1964 = September '64. The one on the right has "?UT" - perhaps "IUT" = 36th week of '64.

Serial number unknown - currently in New Zealand

Grille cloth and baffle replaced, but to judge from the control panel, in good condition otherwise. Transformers look to be original.

Vox AC50, large box, serial number

For small-box amplifiers with grey panels and dome voltage selectors. .

Serial number 1499 - currently in the UK

Sold on summer 2014. Replaced grille cloth and escutcheon plate.

Serial number 1502 - currently in the UK

Mains transformer mounted on its side, but otherwise few changes (the only notable replacement being the voltage selector). One of the blue Hunts preamp cathode bypass capacitors has the code "IST" = 35th week of 1964 = August '64.

Further pics of the amp - currently (July 2018) on .

Serial number 1503 - currently in the UK

Great condition. A replaced mains transformer (probably early on) but otherwise few changes. The mustard capacitors all have the date code B64 = second quarter of 1964. Two of the blue Hunts caps have the code "WIT" = 14th week of 1964. The box, of the early type with vents in the baffle, was given new double-pin corner protectors at some point. A number of these have come away, showing the hole for the original single pin beneath. Thanks to Peter for the pictures.


Fake serial number 1508 - currently in the UK

Above, pictures of the amp sold on ebay, December 2018. Note the tear in the diamond on the grille cloth, top row, four diamonds from the right. No handle (the luggage handle is not fixed on) and no serial number plate.

Sold again with a repro serial number plate with amateur stamping.

Serial number 1578 - currently in the UK

Produced in late 1964. Electrolytic caps replaced, and some resistors here and there, but in good overall condition. Serial number plate fully hand stamped. For further pics, click on the links below.

The amp for some time seems to have driven a pair of LS40 Public Address columns - note that all were provided with new metal corner protectors. Vox certainly offered standard AC50s as PA amps for a time. See the advert below. But whether no. 1578 and the speakers pictured with it were purchased together originally as a set is unknown.

"Melody Maker" magazine, 17th April, 1965.

Serial number 1584 - currently in the USA

Excellent condition. Rotary voltage selector. The box now has a Bulgin socket. Thanks to Larry for the pictures.

Serial number 1594 - currently in the UK?

A replaced output transformer, but otherwise in reasonable condition. Hand-stamped serial number.

Serial number 1607 - currently in the UK?

A nice amp and cab, the cab with early silver Celestion T1088s (note the profile of the dust cover).

Serial number 1678 - currently in the UK?

Sold on ebay uk, November 2012. Mustard caps date to the second quarter of 1964 (B/64). Two of the Hunts preamp cathode bypass caps have the code "WST" = 15th week of 1964 = March '64. Note that the mains lead is hard-wired (original).

Serial number 1686 - currently in Germany

Hand-stamped serial number plate. Thanks to Heinz for the pictures.

Further pictures, paired with a solid state Foundation Bass cab.

Serial number 1709 - currently in the UK

Grille cloth on both amp and cab replaced, but otherwise all good. Hand-stamped serial number.

Serial number 1720 - currently in the USA?

Replaced voltage selector. Hand-stamped serial number. The preamp looks pretty much untouched. Pictures originally .

Serial number 1725 - currently in the USA?

Mains lead hard wired. Hand-stamped serial number. Sold on ebay in 2011.

Serial number 1740 (box only, later amp inside) - currently in the UK

An assembled Foundation Bass set - the cab in particularly good condition. The amp cabinet has probably been recovered in old cloth to match. The AC50 currently in the box is solid state and later, the original amp now gone.

Serial number 1743 - currently in the USA

The amp has been regrilled, but the cloth on the cab, which is in excellent condition along with its roller trolley, is original.

Serial number 1746 - currently in the UK

Voltage selector replaced / modified. The original OT is gone but the amp is in reasonable condition otherwise - only a few changes in the preamp. The cover - in green drab (?) is the one issued with the unit in 1964.


Serial number 1749 - currently in the USA

Click on the buttons below for further pictures of the amp and cab:

A superb AC50 complete with original cover, XLR cable, Foundation Bass speaker cabinet and trolley. The latest dateable component is August 1964, so the amp is likely to have been made early in the last third of '64. Thanks to Craig for the pictures.

Serial number 1763 - currently in the UK

Mains transformer replaced and logo probably from its Foundation Bass cab. The preamp is more or less untouched. The 0.1uf mustard caps have the date code B/64 = second quarter of 1964. Voltage selector gone.

Serial number unknown - currently in the UK

The pictures are just a little too small to be sure, but the serial number looks as though it may be hand stamped. Rotary voltage selector.

From this point serial numbers are machine-stamped (rather than hand-stamped) on the plates

Serial number 1775 (?) - currently in Canada

A highly-polished AC50. Hand-stamped serial number. A couple of ancillary speaker output jacks added on the escutcheon plate.

Serial number 1786 - currently in the UK

A replaced choke, but otherwise in excellent condition. Note that batches of AC50s, including this one, have rectangular silver mica signal caps, probably Lemcos (up by the tone controls). The two main filter caps in the preamp have the code "HUT" = 26th week of 1964 - June '64.

Serial number 1796 - currently in the UK

Voltage selector removed. The amp designation "AC50" is hand-stamped on the plate; the serial number itself machine-stamped.

Serial number 1815 - currently in the UK

Great condition. The preamp is entirely untouched. Original mains lead (hard-wired) still in place.

Serial number 1821 - currently in the UK

A second set of pictures showing the cab's first generation Celestion 18" speaker sprayed in its later 1964 colour - "poly grey" or silver. The earliest units produced for Vox were blue.

Serial number 1855 - currently in the USA

Evidently in good condition.

Serial number 1876 - currently in the UK

One of the filter caps in the preamp has the code "HUT" = 26th week of 1964 = July '64.

Serial number 1915 - currently in the UK

Hand-stamped "AC50", machine-stamped serial number. By the 1970s a Vox factory reverb - the type designed primarily for AC30s - had been fitted to the amp, but unfortunately it had become unusable, producing noise even when off, so was removed. The controls remain. Thanks to Grant for the pictures and details.

Serial number 1938 - currently in the UK

Formerly owned by Noel Gallagher, as the amp below. Sold on Reverb in late 2017. Original dome voltage selector in place (and the original Cannon XLR speaker connectors on the back panel).

Serial number 1946 - currently in the UK

Formerly owned by Noel Gallagher. Sold on Reverb in late 2017. Voltage selector removed. Note the early box - two cut-outs in the baffle behind the grille cloth.

Serial number 1982 - currently in the UK

Serial number plate hand-stamped ("AC50") and machine stamped (serial number itself), New capacitors added in 1973 and probably the replacement mains transformer at that time too. The mustard capacitors have the date codes "B4" and "C4" = second and third quarter of 1964.

Serial number 1999 - currently in the USA

Paired with a US Vox cab (Berkeley).

Serial number unknown - currently in the USA

"AC50" is hand stamped, the serial number, too feint to make out, is machine stamped. The grille cloth is now 1970s Rose Morris. The transformers still have their original stickers. Mustard capacitor date codes: "A4N" and "B/64" = first and second quarter of 1964. One of the pots has the code: "GL" = July 1964.

Serial number 2031 - currently in the UK

Late 1964. Note that V O X is in individual letters on the amp, as no. 1999 above, and no. 2069 below. The cab is late JMI, from 1967. Thanks to Dave for the pictures and info.

Serial number 2069 - currently in Australia

Brown grille cloth. Individual letters for the logo V O X. The underchassis is signed "DE" = Dave Earp who worked at Triumph in the mid 1960s. The transformers have paper stickers with their codes: mains is JMI M 007A; output is JMI D 008A; and choke is JMI X 009A. Thanks to Glen Lambert for the pictures.

Serial number 2072 - currently in Italy

As above, individual letters for the logo; but black grille cloth. Replaced mains and probably output transformers. Pot codes are JL = October 1964. The same blue Hunts capacitors as in the amps above. Sold on ebay in mid 2012.

Serial number 2143 - currently in the UK

Serial number 2147 - currently in the UK

Single letters for the V O X logo as in the amp below. Distinctive Triumph transformers visible through the top grille.

Serial number 2164 - currently in Sweden

A few changed components here and there, but otherwise good. The amp belonged in the 1960s to the bass player of the Swedish band The Sleepstones. Thanks to Lenny for the pictures.

Serial number 2172 - currently in Europe

"AC50" still hand-stamped on the plate.


Serial number 2175 - currently in Scandinavia

Pictures from .

Serial number 21xx - currently in the USA?

Single letters - V O X - for the logo, as in the case of a number of amps on this page. Voltage selector unfortunately missing. Black escutcheon panel for the XLR outputs.

Serial number unknown - currently in the UK

A nice amp. Valve rectified, rotary voltage selector, stickers still on its transformers, and a set of original valves. The Mullard ECC82 has the code B4K2 = Blackburn Factory, 1964, 2nd week of November. Amp probably produced in late 1964 or very early 1965.

Serial number unknown - currently in the USA

Replaced output transformer, but otherwise all there. The two smaller mustard caps have the date code "C3N" = third quarter of 1964. The larger 0.1uf caps have the codes "B5N" = second quarter of 1965.

Serial number unknown - currently in the UK

Mains cable still hard-wired. Pictures from

Serial number unknown - currently in the UK

Old pictures, which though small, show the three valves through the grille, and the lack of a mains connector on the back panel. The preamp looks to be in good order.

Serial number unknown - currently in the USA

Pot codes "GL" = July 1964, so the amp probably produced late 1964. The box, with its Amphenol connectors, is later.

Serial number unknown - currently in the USA?

Probably to be included here - note the old-style black panel for the output XLRs. The cab and trolley may be later however - observe the round Amphenol connector. Early cabs had rectangular Cannons. .

Serial number unknown - currently in the USA

The first picture is before, the other two after restoration. Certainly a dome voltage selector. Output transformer has been replaced. The position of the internal fuse is horizontal (as in Mark 1 amps) rather than vertical.

Valve rectified - currently in the UK - but reboxed

A valve rectified chassis reboxed in a later box. Mustard capacitors and tightly wound transformer leads indicate manufacture by Triumph Electronics. Some extra functionality - a small interstage (or bias?) transformer added under the input jacks.

Serial number unknown - currently in the USA

Condition of box unknown. A solid state plug in rectifier has been substituted for the GZ34. The transformers clearly indicate the amp was made by Triumph.

Serial number unknown - currently in the UK

Ancient pics from ebay. Valve rectified, rotary voltage selector. Not identifiably any of the amps above - there is a distinctive scuff on the back board above the serial number plate.

Serial number unknown - currently in the UK

Paired with a re-grilled Conqueror cab. The three main valves are just visible through the grille in the last picture. Note on the back the white warning plaque, the lack of mains connector, and the black panel on which the XLR speaker sockets sit.