Vox AC50s from the last third of 1964 in serial number order

Valve rectified, small and large box

Roy Orbison with "The Candymen" on stage at the high school gym in Eau Claire, Wisconsin: November 11, 1964. Note the large-box AC50 and Foundation Bass cab at right.

This page covers the transition from the early small-box Vox AC50 - single channel, copper panel, inputs in diamond formation - to the new large-box Vox AC50 mark 2 - twin channel, grey panel. All are valve rectified.

An introductory page on the mark 2 . The schematic (circuit diagram) is OS/053 - see this page. The AC50 is designated the "AC50/2", indicating in this case, the two channels: "Normal" and "Briliant".

Below, an overview of known valve rectified AC50s from the second half of 1964 with serial numbers in the range 1300-1750. One should not assume however that all were units designed for guitar. Some will have been Vox PA50s, which had numbers in sequence with the guitar amps. On the rare survivals - PA amps were often consigned to the scrapheap or plundered for parts in later decades - see this page.

Serial numbers 1300-1750

A principal defining characteristic of all Vox AC50s in this range is that their serial number plates are hand-stamped - both the "AC50" and the number itself:

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From around serial number 1750, the lower panel - the serial number - is machine-stamped.

The amps encompassed on this page were all made under contract for Vox by Triumph Electronics. Triumph was based in Purley. Finished chassis were shipped in batches by road to the Vox Works at Dartford - 119 Dartford Road.

Boxes were then provided, the speaker and mains leads in the amp soldered to the sockets on the back-boards, and serial numbers assigned. Since the chassis were not stored in order of production, one regularly finds older ones with higher numbers than newer ones. They were boxed up simply as they came to hand from the shelves.

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Before the amplifiers were sent out, the serial numbers were noted in ledgers (now lost), along with the destination / name of the shop or person who had purchased or ordered, and type.

Mid to late 1964 was a time of rapid change for JMI. From late August 1964 the principal driving force was the need to meet demand from America - the "Million Dollar" deal forged with Thomas Organ. Production only became fully systematic, however, in 1965 when production got underway in earnest at the Vox / Burndept Works in Erith.

Notes

As one might expect, various transitions take place: grille cloth is brown first then black; voltage selectors change from link to slot, then to dome rotary, which became the standard type. Amp covers are of heavy coloured vinyl with no logo initially, then a lighter-weight black with "VOX" in capitals.

It seems likely that the copper panel diamond input amps with black grille cloth and relatively high serial numbers were made in mid 1964, but not put out for sale immediately.

An overview of the diamond input amps can be found .

The grey panel twin channel amps, so far as one can tell, were all made after July/August 1964. They generally have at least one potentiometer with the date code "GL" = July 1964.

An overview of early AC50 Mark 2s in small boxes can be . Details of the earliest large box AC50 Mark 2s are .

Triumph employees often signed the underchassis of amps in pencil. DE = Dave Earp. RW = Roger White. Both Dave and Roger signed serial no. 1449, below.

Excluded from the register below are the majority of amps with unknown serial number, and those with fake serial number plates:

SURVIVING AMPS

Small box, twin channel, brown cloth - dome voltage selector

Serial number 1311 - currently in the USA

Perhaps in late 1964 a new chassis put into an unused small box (with serial number plate already affixed) for sale.

Pot codes "GL" and "IL" = July and September 1964. Date code of the blue Hunts capacitors "HDT" = 28th week of 1964 = 6th-12th July. The mustard caps are older stock - "B64" = 2nd quarter of '64.

Signatures are "DE" = Dave Earp, and "SR" = Steve Rolfe, who set the bias at "34" volts. The two holes between the EL34s are likely to be later drillings. The amp is built to the original Mark 2 circuit, and has only one bias pot in the appointed place behind the preamp filter capacitors.

Small box, single channel, diamond input, brown cloth

Serial number 1312 - currently in Australia

Sold on ebay in 2014. A nice AC50, apparently untouched electronically. Small output transformer.

Small box, single channel, diamond input, brown cloth

Serial number 1326 - whereabouts unknown

Sold on ebay in 2006. Complete with its original maroon (?) cover. Double speaker outputs. White warning plaque off to side.

Large box, twin channel, brown cloth - link voltage selector

Serial number 1360 - currently in the UK

Large box amp in nice condition (and its original green cover) with a very low serial number. Triumph made. Mustard capacitors have the codes "A4" (first quarter of 1964) and "B4" (second quarter '64). Part of a pot code is just visible in picture 9 - "DL" (?) = April 1964. One of the Hunts 16+16uf filter caps has the code "HNT" = 27th week 1964.

Accompanying the amp, an 18" Foundation bass cab with brown cloth and old-style 18" Celestion driver, though in silver rather than blue. Silver speakers for guitar amps came into being in late May '64. Bass speakers followed suit. For the "alnico silver (Celestion T1088), .

Large box, twin channel, brown cloth - link voltage selector

Serial number 1384 - currently in the UK

An early large-box AC50 - serial number 1384 - and its accompanying brown-fronted Foundation Bass speaker cabinet (no side handles).

Note the link voltage selector. The speaker cable, with its Amphenol XLR connectors, is probably the original. A few visible modifications: a new handle, a new XLR panel, and a replacement mains cable.

At some point the set was owned by the band "Just Men", the name painted on both amp and cab, now mostly erased.

Small box, single channel, diamond input, brown cloth

Serial number 1387 - whereabouts unknown

Reported by J. Elyea.

Large box, twin channel, brown cloth - link voltage selector

Serial number 1411 - currently in the USA (?)

A really nice early large box AC50. No replaced components, the only observable changes being an added output jack socket and a few new control knobs. Chassis signed off in pencil "DE" and "RW" = Dave Earp and Roger White. The date codes of the 0.1uf mustard caps are tantalising indistinct, but probably read "B/64" = second quarter of 1964. One of the Hunts bias caps has the code "HWT" = 21st week of 1964 = May 1964; and one of the preamp cathode bypass caps "WST" = 15th week of 1964 = April '64.

Small box, single channel, diamond input, brown cloth

Serial number 1429 - currently in the USA

Sold on ebay in 2006. Brown grille cloth; white warning plaque; and what look like the original connectors. Input jack sockets are all black. A white pair for the "normal" channel seems to have been reserved for early large box AC50s.

Small box, twin channel, brown cloth

Serial number 1436 - currently in the USA

With an AC30 cab. Amphenol "doughnut"-style mains connector; single rectangular Cannon output socket. Warning plaque centred. "13" chalked on the back board. Pot codes are "GL" and "HL" = July and August 1964.

Pictures above from ebay, 2006. Note the pattern of damage to the serial number plate.

Small box, twin channel, brown cloth

Serial number 1449 - currently in the USA

Brown grille cloth, grey panel, domed voltage selector. Single speaker output. As in the case of no. 1411 above, the chassis was signed off in pencil "DE" and "RW" = Dave Earp and Roger White. Note the "20" chalked inside the box and on the back board. A nice amp.

Large box, twin channel, replaced cloth - slot voltage selector

Serial number 1462 - currently in the UK

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

Small box, twin channel, brown cloth / discoloured black

Serial number 1485 - currently in the UK

Grille cloth of both amp and cab originally black, but now faded. Note that the cab is of the later type with "handles" let in the side. We pass over the amp's handle in silence.

Large box, twin channel, replaced cloth

Serial number 1499 - currently in the UK

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

Small box, twin channel, black cloth

Serial number unknown - currently in the UK?

Black grille cloth. A replaced mains transformer, but otherwise not in bad shape. "5" chalked inside the box and on the back board.

Large box, twin channel, brown cloth

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 .

Large box, twin channel, brown cloth

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 cathode bypass caps have the code "WIT" = 14th week of 1964; one of the 16+16uf filter caps has "HNT" = 27th week 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.

Small box, twin channel, brown cloth

Serial number 1506 - currently in the UK

Sold on ebay. Replaced mains transformer and choke. Condition otherwise good.

Large box, twin channel, black cloth

Fake serial number 1508 - currently in the UK

Beware, fake serial number plate added by a North London dealer. The amp, which is valve rectified, was sold on ebay in 2018 without a plate (and at least one other thing that magically appeared in the subsequent sale). Pictures before and after exist.

Small box, twin channel, brown cloth

Serial number 1524 - currently in the UK

Sold on ebay in 2011. Brown cloth, grey panel. Triumph-made, as all the AC50s pictured on this page - note the highly twisted leads from the transformers. Original connectors on the back panel. Sold on ebay again in late 2013.

Small box, single channel, diamond input, black cloth

Serial number 1532 - currently in the UK

Sold on ebay in 2006 (seller in Falkirk, Scotland). Amp and cab are in full working order. The latter is designated LFA52, serial number 11296. Thanks to Laurence for the info.

Wonderful original condition is evident from the pictures. The speaker cab is probably a very early solid state Foundation Bass cab - the driver is a Celestion T1296 (first logged in the Celestion record book in October 1966), there is a port underneath, and the baffle screws have been sealed with yellow paint (a typically later practice). The logo however is still of the old style, so this is probably a transitional unit between the valve and solid state lines.

Small box, single channel, diamond input, black cloth

Serial number unknown - currently in France

A splendid amp and cab set possibly with original black cloth.

Large box, twin channel, black cloth

Serial number 15xx - currently in the USA?

White warning plaque, XLR speaker connectors.

Large box, twin channel, black cloth

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.

Large box, twin channel, black cloth

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.

Large box, twin channel, black cloth

Serial number 1594 - currently in the UK?

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

Large box, twin channel, black cloth (discoloured)

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).

Large box, twin channel, brown cloth, perhaps black discoloured

Serial number 1620 - currently in Germany

A good early AC50. The voltage selector has been removed.

Large box, twin channel, black cloth (discoloured)

Serial number 17xx - currently in the USA?

Sold on ebay c. 2009. Brown grille cloth; as above, voltage selector missing unfortunately.

Large box, twin channel, brown cloth, perhaps black discoloured

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).

Large box, twin channel, black cloth (discoloured)

Serial number 1686 - currently in Germany

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

Large box, twin channel, regrilled

Serial number 1709 - currently in the UK

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

Large box, twin channel

Serial number 1720 - currently in the USA?

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

Large box, twin channel, black cloth (discoloured) - slot voltage selector

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.

Large box, twin channel

Serial number 1725 - currently in the USA?

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

Large box, twin channel, black cloth ) - slot voltage selector

Serial number 1727 - currently in the UK

Sold on ebay.uk 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.

Large box, twin channel, brown cloth

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.

Large box, twin channel

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.

Large box, twin channel, black cloth

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.

Large box, twin channel, brown cloth

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.

Valve rectified, link voltage selector

Serial numbers unknown