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 can be found here . 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:
.
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.
.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.
Below, a picture published in the local Dartford press on 4th September 1964 of early AC50 mark 2 Foundation Bass sets being boxed up for export to the States.
Published in the local Dartford press, 4th September, 1964 - in terms of these exports, quick action - the "Million Dollar Deal" with Thomas Organ had been made only 10 days earlier at the Russell Hotel Trade Fair in late August.
Below, a detail from a photo taken in 115 Dartford Road later in September 1964, the result of the activity pictured above - AC50 Foundation Bass sets ready for shipping to the USA, the Thomas Organ model number - "V-1-14" - stamped on the cartons.
Mid to late September 1964
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 on this page.
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 found here. Details of the earliest large box AC50 Mark 2s are are being collected together here.
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.
The baffles of the very earliest large boxes are solid. Later - from serial numbers in the high 1400s - two vents were provided. One can see the outlines in the bagging of the grille cloth. Also to note, the backboards of these boxes have a single fixing point on their top edge. The backs of later boxes have two.
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 - link voltage selector
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 - link voltage selector
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 1338 - currently in the UK
May 2023: further details to follow.
Large box, twin channel, brown cloth - link voltage selector
Serial number 1354 - currently in the UK
The Hootas were a Hamburg band. The group played the Star Club with other local bands on New Year's Day 1965, but whether they had the amp early on is not known. In common with other early large box AC50s, there is no engraved escutcheon plate for the XLR sockets - simply in this case a panel of aluminium. The original XLR cable (supplied by JMI with the amp) still survives.
Further pictures can be found on this page, and the pages linked from it.
The box is of "type 1" with solid baffle, brown grille cloth, and a single fixing point on the top edge of the back board. A second type with vents in the baffle comes in soon after - with serial numbers in the 1400s and beyond. The corner protectors have gone.
DATE CODES: all potentiometers are "BL" = February 1964. All mustard capacitors are "A4" = first quarter of 1964. Visible Hunts capacitors have: "WST", "HWT" and "HNT" = 15th, 21st and 27 weeks of 1964 respectively. The 27th week is June 29th - July 5th.
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), see this page.
Large box, twin channel, brown cloth - link voltage selector
Serial number 1367 - currently in Germany
Another early large box AC50 mark 2, serial number 1367 with what is probably a later Foundation Bass speaker cabinet - double pin corners, 18" Celestion greenback, grille cloth redone in brown. Note the aluminium plate for the speaker connectors on the back panel - much as serial number 1354, above. In the preamp, the Mullard mustard caps have date codes A4N and B/64 = first and second quarters of 1964. One of the blue Hunts filter caps has "HNT" = 27th week of '64. Two of the pots have either "BL" or "DL" = February or April 1964.
Large box, twin channel, brown cloth (originally) - link voltage selector
Serial number 1383 - currently in the UK
The amp was bought by its present owner around 1976 from a music shop in High Wycombe. When he joined the navy, it travelled the world, being used for gigs at foreign ports, then later in and around Southampton. The grille cloth was originally brown. The white control knobs are temporary replacements following the renewing of the pots. The electronics are in excellent original condition. In common with a good many amps on this page, the Mullard "mustard" capacitors have date codes "A4N" and "B4" = first and second quarter of 1964. The Welwyn cement resistor at the speaker terminal block has the code "VF" = June 1964. Typical of the earliest large box AC50s is the metal mounting plate for the output sockets on the back panel - see numbers 1354 and 1367 above, and number 1394 immediately below. Thanks to Nick for the pictures.
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
Large box, twin channel, black cloth - dome voltage selector
Serial number 1393 - currently in the UK
Above, the amp prior to being returned to working order. Date codes of the Mullard mustard capacitors are "D3N", "A4N", "B/64", and "C4N", respectively, last quarter of 1963, and first, second and third quarters of 1964. One of the blue Hunts preamp caps has "HYT" = 20th week of 1964, and one of the pots looks to have "GL" = July '64. The amp came with its original Mullard yellow-print preamp valves. Thanks to Andy for the pictures and those below.
Returned to full working order
The output transformer proved to be defective - replaced now with a unit made by Dagnall. A couple of capacitors also had to be renewed. The EL34s are new label Mullard Xf4s from c. 1971 and the GZ34 a Tungsram. Otherwise the amp is pretty much as it was when it left Dartford Road.
Large box, twin channel, brown cloth - link voltage selector (?)
Serial number unknown - currently in the USA (?)
An early large box AC50 mark 2, sold on ebay, probably originally with a serial number in the range 1400s-1600, last third of 1964. The only visible date codes are on certain of the Mullard mustard capacitors - "A/64" = first quarter of 1964. Black escutcheon plates for the XLRs on the back panel were used in 1964 on all but the very earliest large box AC50 mark 2s.
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.
Large box, twin channel, brown cloth - dome voltage selector
Serial number 1420 - currently in the UK
A superb set, brown cloth all round. Thanks to Mark for the pictures. The arrangement of the back panel is similar to that of serial number 1360 (above) but with the addition of a further Cannon XLR socket (early round instead of rectangular) for the second of the two LS40 Public Address columns. Note the old-style logos - "VOX" in cursive - on the hand-wheels of the tilt-back stands. AC30 Super Twin amplifier sections and AC50s were sometimes supplied by JMI in place of the dedicated PA amplifiers that the company produced (from early 1964). See for example, the advert at the top of this page.
Small box, twin channel, diamond input, brown cloth - dome voltage selector
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 - dome voltage selector
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.
Large box, twin channel, black cloth
Serial number 1467 - currently in Denmark
Recently sold in Denmark, serial number 1467 - black escutcheon plate for the speaker output sockets.
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 - dome voltage selector
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 - dome voltage selector
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 Reverb.
Large box, twin channel, brown cloth - dome voltage selector
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 - voltage selector replaced
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 - link voltage selector
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 - link voltage selector
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 - dome voltage selector
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 - dome voltage selector
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 - dome voltage selector
Serial number 1594 - currently in the UK?
A replaced output transformer, but otherwise in reasonable condition. A black escutcheon on the back panel for the speaker sockets. Hand-stamped serial number.
Large box, twin channel, black cloth (discoloured) - dome voltage selector
Serial number 1599 - currently in the UK
Brown (?) grille cloth. White warning plaque, grey escutcheon for the speaker sockets on the back panel. Hand-stamped serial number plate (the first "9" originally stamped wrongly as a "5").
Large box, twin channel, black cloth (discoloured) - dome voltage selector
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).
Updated
Large box, twin channel, black cloth - dome voltage selector
Serial number 1610 - currently in the UK
Pots with date code "GL" = July 1964. Mullard mustard caps with date code "B4N" and "B/64" = second quarter of 1964. One of the large blue Hunts 32uf filter caps has "HNT" = 27th week of 1964. The output transformers still bears the original part code, stamped in ink - probably 105736 - the last two digits are smudged. The pencil signature of the person at Triumph who signed the chassis off is difficult at present to make out. The cab is a UL460 bass cab, original speakers replaced.
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.
NEW
Large box, twin channel, black cloth - dome voltage selector
Serial number 1628 - currently in the USA
Amplifier section and speaker cabinet (with trolley), both sections with new brown cloth. The amplifier has a replacement handle.
Large box, twin channel, brown cloth, perhaps black discoloured - dome voltage selector
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) - dome voltage selector
Serial number 1686 - currently in Germany
Hand-stamped serial number plate. Thanks to Heinz for the pictures.
Large box, twin channel, brown cloth - voltage selector removed
Serial number 1705 - currently in the UK
Excellent condition. Power section (underchassis) and preamp are remarkably clean. The Hunts caps have date codes "WST" and "HNT" = 15th and 27th weeks of 1964 respectively. Mullard mustards: "D3N", "A4N" and "B/64" = last quarter of 1963, first and second quarters of '64. The pots have "GL" = July 1964. On the back panel, a black traffolyte escutcheon plate for the Cannon speaker sockets. Thanks to Chris for the pictures.
Large box, twin channel, regrilled - dome voltage selector
Serial number 1708 - currently in the UK
Good external condition. Hand-stamped serial number plate. Grille cloth renewed with new production cloth. The Switchcraft speaker sockets are later additions.
Large box, twin channel, regrilled - dome voltage selector
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, 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
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 - dome voltage selector
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 - dome voltage selector
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 - dome voltage selector
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. Note that the baffle of the amplifier cabinet has vents. Thanks to Craig for the pictures.
Valve rectified, link voltage selector
Early production chassis. Serial numbers unknown
Serial number unknown - currently in the USA?
Apparently missing its original output transformer (unless it is a short one now remounted on top of its underchassis frame), otherwise in excellent condition. Grille cloth replaced. The mains transformer has the code "JMI M 007A". Glen Lambert has kindly provided pictures of a later amp that has the same paper notes of the transformer codes - serial number 2069, posted on this page. These codes are regularly found on the transformers of the earlier single channel amps - first and second generation (two input and four input).
Serial number unknown - currently in the USA?
Link voltage selector originally (see the last pic), white warning plaque, but 1/4 inch jack connectors instead of XLRs. Pictures from this site.
Serial number unknown - currently in Germany?
Sold on ebay in 2005 with a Foundation Bass cab. Replaced grille cloth, handle and output socket plate.
Serial number unknown - currently in the UK?
Brownish grille cloth - or perhaps black faded to brown; link voltage selector visible in the second image, set to 245V.
Serial number unknown
Black grille cloth. A replaced output transformer, and modified back panel - note the jack sockets protruding through the serial number plate. One of the mustard caps has the code "C4N" = third quarter of 1964.
Serial number unknown
Black grille cloth, as on the amp above; also mustard caps dated "C4N" = third quarter of 1964. Voltage selector pill missing.
Serial number unknown - currently in the USA?
Sold on ebay in 2005. Brown grille cloth (normally a sign of an early large box AC50); voltage selector missing unfortunately. Note that the baffle has vents.
Serial number unknown
A fabulous assemblage - a portable AC50. Mains transformer replaced, and some new capacitors in the preamp, but otherwise all there. The remaining 0.1uf probably bears the date code 7/64 = July 1964.
Serial number unknown - currently in Europe?
Old images from ebay. The link voltage selector, set at 225V, is just visible in the second image.
On to page on valve rectified AC50s, serial numbers 1700 to 2200.