A detail from the JMI fold-out catalogue of late 1963.

This page naturally takes its cue from the page on earlier Vox AC4s. To all intents and purposes the AC4 was simply the AC2 renamed. For the AC2 of late 1960 into 1962 see this page.

From February 1963 the standard list price of the AC4 was 22 guineas (£23 and 2 shillings). "Musicland", the Jennings shop in Bexleyheath, set it a little lower, however, in adverts placed in the popular national press - £18 and 18 shillings - the price presumably just for the amp, no packing box, no cover, and perhaps no brochures.

November 1963. The amplifier mentioned at £18 18 shillings is the AC4.

The standard printed "Musicland" pricelist of late 1963 gives the standard JMI price though: 22 guineas (£23 and 2 shillings):

Detail of the "Musicland" pricelist, late 1963.

Below, one of the last appearances of the AC4 in a formal JMI source - the full pricelist of November 1965 - £26 and 5 shillings:

November 1965.

Assembly

In 1963 and 1964, Triumph Electronics continued to assemble AC4 chassis under contract for JMI, along with chassis for the Vox Domino range, and the AC50. On the Dominos - for the most part AC4s by another name - see the main index page here. Components at first were largely the same as those used in earlier amps. By 1963 Triumph had begun to use blue Hunts electrolytic capacitors, and Mullard mustard signal caps. Resistors continue to be the white Eries of old. Jack sockets were supplied by Re-an Products Limited, based on Burnham Road in Dartford, just a step away from the Jennings Works.

Finished chassis were driven to Dartford Road where they were fitted, sometimes after a time in storage, into cabinets for sale. The speakers wired in at the JMI Works were generally grey 8" Elac drivers, impedance 3-4 ohms. Serial number plates are still hand stamped.

Transformers: as in 1962 and early 1963, mains transformers were supplied by J.D. Electronics. AC4 serial number 3921 however, along with an amp with an unknown number, have units labelled "Technical Components (Weybridge) Ltd, St Cross Road, Farnham, Surrey". Output transformers, normally stamped "5200" (though in some instances "5000"), were sourced, probably by Triumph, from Richard Allan from late 1962 through to 1965.

Control panels: a gold-pink colour, legends for INPUTS / VOLUME / SPEED / ON-OFF TONE / Voltage selection. Alan Griffin, who worked at Triumph from 1963 to 1965, remembers fitting the Domino range with black panels and white control knobs - the chassis of the Domino amps were much the same as the AC4.

Cabinets: thin-edged at first; then (beginning with serial numbers in the mid 3600s) thick-edged sides, top, and bottom with midly radiused edges. A little later on one finds more pronounced radiuses (standard form on other JMI models too).

Cabinet coverings: thick dimpled (sometimes speckled) dark grey vinyl or black basketweave.

Speaker: a single 8" grey Elac. The codes appears to be "8C/164", visible in serial numbers 2981 and 3074, and "8C/175" for serial number 3245. Elac subsequently supplied a different type, sprayed hammertone silver, "drum" magnet cover, stamped "8C/177".

Export to the USA

From late 1964 into 1965, a sizeable number of AC4s were exported to Thomas Organ in the USA and redesignated as the "V-1-1" in the Thomas catalogue. They were sold both in music shops and in department stores, often as a package aimed at teenagers and students: "A Vox Amplifier and Guitar, as used by The Beatles!". Occasionally the pitch was that they would make an ideal graduation present. In mid to late 1965 the AC4 was phased out however. The smaller JMI models were replaced by solid state amps of Thomas's own design.

A detail from the Thomas Organ "Million Dollar Deal" catalogue of late 1964 / early 1965.

Below, a picture published in March 1965 of Hal Morris in his music store in Lansing (Illinois) with an AC4, a pair of Line Source 40 speaker columns, and what looks to be a Vox Stroller guitar.

Published on 23rd March, 1965.

The Thomas Organ documentation (and other US material) relating to the amp will be presented on a forthcoming page.

Overview of surviving amps

The principal circuit diagram for later Vox AC4s (and the Vox Domino Normal) is OS/051, drawn up by Albert Hogben on 6th March, 1964. Thomas Organ drew the circuit out anew, incorporating the sheet in all editions of its Vox Amplifiers Service Manuals (late 1966 to 1969).

Serial number 3033

Smooth grey vinyl; brown grille cloth; brass vents. Components in the preamp fairly extensively renewed.

Serial number 3034

Front illustrated by J. Elyea, "Vox Amplifiers", p. 404.

A brief run of plastic serial number plates

Plastic plates were also used on AC30 Twins with serial numbers in the 11000s, early 1964 - see this page.

Serial number 3062

Basketweave vinyl; brown grille cloth. The speaker is a Goodmans (probably a replacement for the original). The serial number plate is of the same (temporary) type as 3074, below.

Serial number 3074 - currently in the UK

Basketweave vinyl; brown grille cloth; brass vents. A plastic serial number plate, as on early Vox Domino amplifiers - see this page. Original grey Elac 8C/164 speaker and egg-shaped footswitch still present.

Serial number 3087

Back to standard metal plates.

Serial number 3089 - currently in the USA (?)

Basketweave vinyl; old black JMI grille cloth (from some other source?); brass vents on the cabinet top. In the preamp, Mullard mustard capacitors with date code "D3N" = last quarter of 1963 for their manufacture. The main Hunts capacitor in the power section has "HAI" = 29th week of 1963. Original grey Elac speaker and egg-shaped footswitch still present. Thanks to Ian for the pictures.

Serial number 3132

Exterior shots only. Basketweave vinyl; brown grille cloth; brass vents on the cabinet top; grey Elac speaker.

Serial number 3236 - currently in the USA (?)

Brown grille cloth; smooth dark grey vinyl; black vents with "VOX" logo. The original shipping box survives - an extremely rare thing.

Serial number 3238

Smooth (speckled) dark grey vinyl; black vents on the cabinet top. Model/type of speaker currently unknown.

Serial number 3245

Chassis assembled by Triumph. Basketweave vinyl; brown grille cloth. In the preamp, Mullard mustard capacitors with date code "D3N" = last quarter of 1963 for their manufacture. Most of the electrolytics have been renewed. The original valves may still be present - at least one yellow-print Mullard with the paint code "Kx" = some month in 1963. The original Elac 8C/175 speaker is in place, on its frame "3459" and "D138489".

Serial number 3306

Front illustrated by J. Elyea, "Vox Amplifiers", p. 404.

Serial number 3308

Exterior shots only. Smooth (slightly speckled) dark grey vinyl; brown grille cloth. Original grey Elac still in place.

Serial number 3391

Speckled grey vinyl; brown grille cloth; black vents with "VOX" logo. The footswitch is of the same type issued with Domino Reverb combo amplifiers, also assembled for JMI by Triumph - serial number 1635, for instance, on this page. Thanks to Martin for the pictures.

Serial number 3395

Speckled dark grey vinyl; brown vinyl; black vents with "VOX" logo. In the preamp, Mullard mustard caps. with date code "D3N" = last quarter of 1963 for their manufacture. The speaker has been renewed.

Serial number 3496

Speckled dark grey vinyl; brown vinyl; black vents without "VOX" logo. In the preamp, Mullard mustard caps. with date code "D3N" = last quarter of 1963 for their manufacture. Output transformer stamped "5200". The yellow-print Mullard rectifier valve has the paint code "KK" = September 1963. The speaker has been replaced.

Serial number 3644

Thick-edged cabinet; basketweave vinyl; brown grille cloth. Still a hand-stamped serial number plate. The speaker appears to be a Goodmans with scalloped openings in its frame.

Machine stamped serial numbers

Where AC30s are concerned, machine-stamped plates come in around serial number 13000 (mid 1964) - see this page.

Also to note that at around this point AC4s were issued in thick-edged cabinets (see above, serial number 3644 too).

Serial number 3699

Serial number 3720

Thick-edged cabinet; basketweave vinyl; brown grille cloth. Silver Elac speaker, "8C/177" stamped on its frame.

Serial number 3751

Thick-edged cabinet; basketweave vinyl; brown grille cloth; black vents without "VOX" logo. In the preamp, a Mullard mustard caps still with date code "D3N" = last quarter of 1963 for their manufacture. The speaker has been replaced.

Serial number 3772

Basketweave covering; brown grille cloth. The brass vents on top of the cabinet are custom replacements. Mullard mustard caps still with date code "D3N" = last quarter of 1963 for their manufacture. Output transformer stamped "5200". Silver Elac 8C/177 speaker.

Serial number 3917

Exterior shots only.

Exports to Thomas Organ in the USA underway from this point

AC4s made for export to Thomas Organ in the USA (following the "Million Dollar Deal" announced in late August 1964) can be identified the presence of a supplementary grey Radiospares capacitor (0.05uf, 800v) running from the mains supply to ground. These were fitted to suppress noise at switch on. AC50s and AC100s intended for export to the USA were fitted with similar caps.

Centre, grey Radiospares 0.05uf mains "snubber" capacitor removed from AC4 serial number 3921 below.

From this point one also finds preamp valve sockets fixed to the chassis with bolts rather than rivets (Triumph's normal procedure). Whether the bolts were used only on AC4s made for export is not certain at present.

Serial number 3921

Speckled grey vinyl; brown grille cloth. Made for export to the USA. In the preamp, Mullard mustard caps date codes "D3N", "A4N" and "B4N" = respectively last quarter of 1963; and first and second quarters of 1964 for their manufacture. Mains tranformer with the label of "Technical Components (Weybridge) Limited". Output transformer stamped "5000". Silver Elac speaker, "8C/177" stamped on its frame.

Serial number 3941

Front illustrated by J. Elyea, "Vox Amplifiers", p. 404.

Serial number 3966

Exterior shots only.

Serial number 4078

Basketweave covering; brown cloth; black vents with "VOX" logo. In the preamp, Mullard mustards with date codes "A4N" and "B4N" - respectively first and second quarters of 1964. The original footswitch and silver Elac 8C/177 speaker are in place.

Serial number 4150

Smooth dark grey vinyl; brown grille cloth; black vents. In the preamp, Mullard mustards with date code "B4N" = second quarter of 1964. Produced for export to the USA - note the grey Radiospares cap (at right) from mains supply to ground. Preamp valve sockets fixed with bolts rather than rivets. . Original Elac 8C/177 present and correct. Thanks to John for the pictures.

Serial number 4163

Heavy speckled dark grey vinyl; brown grille cloth; black vents. Silver Elac speaker still in place. No shots of the electronics at present.

Black grille cloth from this point

Serial number unknown

Chassis assembled by Triumph. Smooth dark grey vinyl; probably black cloth. Produced for export to the USA. In the preamp, Mullard mustard caps with date code "B4W" = second quarter of 1964. Preamp valve sockets fixed with bolts rather than rivets. Mains transformer labelled "Technical Components (Weybridge) Limited". The output transformer is stamped "5000" rather than "5200". Silver Elac 8C/177 speaker.

1965

Some chassis now assembled for JMI under contract by Burndept Electronics, chassis numbers stamped by the ECC83 preamp valve. See the entry for serial number 4257, below. Chassis numbers were kicked off at 1000.

Serial number 4257

Chassis number 1216. Assembled by Burndept. Basketweave vinyl; black grille cloth; black vents with "VOX" logo. In the preamp, Mullard mustards with date codes "C4N" and "D4N" = third and last quarters of 1964 for their manufacture. A clamp is provided for a Radiospares "snubber" capacitor but one was evidently never fitted, so the amp is unlikely to have been produced for the US market. The silver Elac has "11461" on its frame (November 1964?).

Serial number 4302

Chassis assembled by Triumph. Basketweave vinyl; black grille cloth. In the preamp, Mullard mustards with "B4N", C4N" and "D4" date codes = second, third, and fourth quarters of 1964. The mains transformer (made by J.D.Electronics) is stamped "KC" in purple, indicating that the chassis was inspected at the Vox Works in Erith. Output transformer stamped "5200". The speaker is a later replacement.

Serial number 4363

Note

A huge gap here at present. Were some of the amps caught in the fire at the West Street Works (Erith) in early December 1965?

Serial number 4761

Basketweave vinyl, black grille cloth, black vents. In the preamp, Mullard mustard caps with "B4N", "C4" and "D4N date codes = second, third and last quarters of 1964 for their manufacture.

Serial number 4767

Serial number 4779

Front illustrated by J. Elyea, "Vox Amplifiers", p. 405.

Serial number 4785

Attached to the speaker, a JMI inspection tag dated 24th May 1966.

Serial number 4790

Serial number 4881

Reported by Jim Elyea, "Vox Amplifiers", p. 529.

Back to the page on earlier AC4s.