The AC10 Twin was first brought to market by JMI in the late autumn of 1961 in company with the new AC15 Twin and AC30 Super Twins - a substantial expansion of the range. Publicity for the AC10 initially was confined to typescript announcements and pricelists - and presumably display in the Jennings shop at 100 Charing Cross Road. In 1961 there was no Russell Hotel Trade Fair. Manufacturers were left to their own devices. Curiously Jennings did not list the AC10 Twin in its pricelists in "Melody Maker" magazine until May 1962. Perhaps no-one thought to update the roster of amps encompassed.

Announcement from the late autumn of 1961.

The first image, reprinted in various flyers through to 1963 and illustrated at the head of this page, probably stems from spring '62 at latest, possibly late 1961. An identical image was used in a flyer printed in late 1962 to accompany the Russell Hotel Trade Fair.

JMI flyer, late 1962. The new boys (displayed at the Fair) were the T60 Bass amplifier and the Transonic.

In October 1961, JMI listed the Twin at £56 and 15 shillings. This should really have been £57 and 15 shillings (55 guineas). The single speaker AC10 was pitched at £47 and 5 shillings (45 guineas). A page on the split-front single speaker AC10 of 1961-1965 can be found here.

October 1961.

Prices, February 1963.

Although a further pricelist from early 1963 indicates plainly that prices had changed - 47 guineas for the single speaker model, 57 guineas for the Twin - the list from February 1964 still gives 45 and 55 guineas respectively (£47 and 5s; and £57 and 15s).

Prices, early 1963, flyer from Kitchens in Leeds. The amplifiers on the front are all in beige vinyl. There is no mention of the AC10 Super Reverb Twin.

Prices, February 1964.

In early 1964, the price outlined in an earlier pricelist (early 1963) became reality: the Twin at 57 guineas, and the single speaker AC10 at 47 guineas - not inconsiderable amounts, though a good number of amps will have been sold on Hire Purchase (an initial deposit followed by a series of fixed monthly payments spread over 18 months).

Production / assembly (late 1961 to 1964)

AC10 chassis were initially assembled for JMI by Triumph Electronics in Purley. There was no difference between those that went into single speaker AC10 cabinets and those allocated to Twins. Triumph normally sent its finished chassis to Dartford Road, where final assembly took place, in batches by road. It is perhaps worth noting that no Twin with a black control panel has so far come to light - perhaps indeed none ever had one. The rule as it stands seems to be copper initially, then grey later on (from mid to late 1964).

On the types of panel used at various points in production, see Glen Lambert's page - Vox AC10 control panels.

The lowest serial number definitively known for a Twin at present is 3526 - see the overview of surviving amps further down this page - its chassis assembled in the second quarter of 1962. Quite how many preceded it is unknown at present; nor is there any evidence to indicate whether or not the very first had black panels, a question that also surrounds the first AC30 Super Twins. Things moved and changed quickly in the early 1960s. In terms of firm facts, the earliest single speaker AC10 definitively known to have a copper panel is serial number 3496. Serial number 3433, in an early "split-front" box, has a black panel.

From some point in the 3600s, Twin cabinets were evidently occasionally covered in heavy smooth black vinyl as used on certain AC30s, fawn (beige, tan, etc) having been the norm up to that point. Slightly later a thinner textured black vinyl was used. Fawn seems to have been abandoned in the high 3900s / low 4000s.

The Twin cabinets are thought largely to have been made by Henry Glass's company "Gla-Rev", though it has to be said that none survives with a maker's label or stamp. Some were evidently made by another supplier however - see for instance the case of the amp with a serial number in the 3900s below. The dimensions given by JMI for the AC10 Twin were 24" x 18" x 9".

Speakers at first were Goodmans 10" drivers, 15 ohms apiece, grey ribbed frame, with a red label around the magnet in the style of the Axiette 8", though the 10" units were never (officially at least) part of the "Axiette" range. JMI wired the Goodmans in parallel for a total impedance of 8 ohms. Some of the earlier ones have mounts on their frames for transformers.

In early 1963 - starting with AC10s with serial numbers in the low 3800s - Elacs with handsome blue frames (specially produced for JMI) were introduced in place of the Goodmans, possibly triggering the price increases briefly indicated in at least one pricelist. The model was 10N/81, 15/16 ohms, around 8-10 watts handling each in an open-back cab.

One of a pair of Elacs with "Vox Sound Equipment Limited" labels in an AC10 Twin from mid 1963.

Another factor that came into play at this point was the contracting out of the assembly of chassis to Westrex to augment and eventually take over from Triumph. Triumph was a relatively small concern. The popularity of the AC10 - particularly the Twin - began to snowball in 1963.

Chassis assembled by Westrex are easy to spot: red checker's dye on the solder joints and the use of gold-coloured WIMA Tropyfol capacitors in the preamp instead of Mullard mustards (as used by Triumph); brown 1/2 watt Dubilier resistors instead of white Eries; and black and white plastic Rendar jack sockets instead of the metal-topped RE-ANs of Triumph.

A Westrex chassis from 1963, its general format exactly as those produced earlier on by Triumph. From left to right on the plinth: choke; output transformer; the EZ81 rectifier valve with the main filter capacitor behind it; two EL84 valvesl mains transformer. The preamp valves, left to right, are: an EF86 (input), ECF82 (tremolo and drive), and an ECC83 (phase inverter).

Triumph by and large used transformers sourced from J.D. Electronics (factory in Corsham, Wilts.). The code numbers were: mains = "RT.254"; output = "MS.377"; and choke = "MS.378". Only one output tap was connected to the terminal block in the preamp - 15 ohm for the single speaker AC10 and 8 ohm for the Twin. The unused wire was left unconnected in the underchassis. Westrex mainly used Albion - paper stickers occasionally remain on the transformer fronts.

The J.D. Electronics mains transformer in AC10 serial number 3874.

An Albion sticker on an AC10 output transformer.

A couple of things to bear in mind: (1) finished chassis might remain on shelves at Dartford Road for some time before being used; and (2) chassis would not necessarily be taken from the shelves/store in any particular order for final assembly.

Material relating to the AC10 Super Reverb Twin, introduced in February 1963, can be found on this page.

Covers

Early covers were made of "plasti-leather" and came in three main colours: red, green, and brown. So far as survivals are concerned, red seems to have been the most common.

An overview of surviving AC10 Twins

Entries for single speaker AC10s are given principally for orientation and comparative purposes (where component date codes are known and useful, for instance). Material on the single speaker AC10 "Throwbacks" of late 1960 / early 1961, split-front cabinets, modified G1/10 chassis, can be found on this page. For the time being the majority of entries below are for Twins.

The JMI circuit diagram for the amps registered below is OS/008. OS/008 is not a "build sheet" however, simply a schema drawn up for repairmen. In many respects, the Thomas Organ sheet for the AC10 (V-1-3) - encompassed in its "Vox Amplifiers Service Manual" - expresses the details better.

Serial number 3433 - single speaker

AC10 single speaker, split front cabinet, four inputs, still black panel. Early to mid 1961. Black WIMA Tropydur capacitors with date codes "30", "70", and "100", respectively March, July and October 1960 for their manufacture in Germany. A set of pictures of the amplifier can be found on this page.

Serial number 3496 - single speaker

AC10 single speaker, split front cabinet, copper panel. Goodmans speaker with red magnet (as in the Twin pictured below). Late 1961 (?).

Serial number high 3400s / low 3500s (?)

Pictured on John Chambers's website at the foot of this page. Chassis assembled by Triumph; J.D. Electronics transformers (not Wodens as John says). In the preamp, a series of Mullard mustard capacitors with "D1" date codes = last quarter of 1961. The codes on others are not legible. The date on the blue Hunts electrolytic may be "TT Y" = 44th week of 1960.

Serial number 3526

Chassis assembled by Triumph. Original Goodmans 10" drivers in place. In the preamp, the Mullard mustard capacitors have date codes "D1" and "A2N" = last quarter of 1961 and first quarter of 1962, the chassis likely to have been assembled in the second quarter of '62.

Serial number 3578 - single speaker

Single speaker (perhaps replaced). Chassis assembled by Triumph. In the preamp, Mullard mustard capacitors with "A2N" and "B2N" = first and second quarters of 1962 for their manufacture.

Serial number in the 3600-3700s

Chassis assembled by Triumph. Cabinet covered in heavy smooth black vinyl. In company with the chassis of serial numbers 3618 and 3622 (single speaker AC10s), the majority of Mullard capacitors in the preamp have the date code "B2N" = second quarter of 1962. Grey frame Goodmans speakers (with transformer mounts and red band around the magnet), wired in parallel.

Serial number 3618 - single speaker

Single speaker. Chassis assembled by Triumph. In the preamp, Mullard mustard capacitors with "A2N" and "B2N" = first and second quarters of 1962 for their manufacture. The main Hunts filter has "HSH" = 25th week of 1962. The original red label Goodmans speaker is still in place as is the circular (domical) footswitch.

Serial number 3622 - single speaker

Chassis assembled by Triumph. Beige vinyl; black luggage handle. In the preamp, Mullard mustard capacitors with "A2N" and "B2N" date codes = first and second quarters of 1962 for their manufacture. The main Hunts filter cap. has "HSH" = 25th week of '62. The single speaker is a red label Goodmans. The original circular (domical) footswitch is still present.

Serial number 3631

Chassis assembled by Triumph. Original Goodmans 10" drivers in place. Pictures from Jim Elyea, pp. 344 and 347.

Serial number 3643

Serial number 3689

Smooth black vinyl. Black luggage handle. In the preamp, Mullard mustard capacitors with visible date codes "A2N" = first quarter of 1962. Possibly (though not certainly) one with "B2N" = second quarter of '62. What look to be the original blue Elacs are still in place. The original cover survives too. Most AC10s at this point have a circular (domical) footswitch. The egg-shaped switch accompanying this amp is likely to have come from another source.

Serial number 3690

Smooth black vinyl. Black luggage handle. Chassis assembled by Triumph. In the preamp, Mullard mustard capacitors with date codes "A2N" and "B2N" = first and second quarters of 1962 for their manufacture. Speakers are red label Goodmans. The egg footswitch is a later replacement.

Serial number 3697 - single speaker

Chassis assembled by Triumph. Beige vinyl; black luggage handle. In the preamp, Mullard mustard capacitors with "A2N" and "B2N" date codes = first and second quarters of 1962 for their manufacture. One of the pots has the date code "EJ" = May 1962. Speaker and footswitch are replacements.

1963

Blue Elac speakers (model 10N/81) normal from this point. The earliest known at present are in AC10 serial number 3689 (above). Some chassis appear to have been made by Westrex (serial number 3805).

Serial number 3724 - single speaker

Chassis assembled by Triumph. Original black vinyl; black luggage handle. In the preamp, Mullard mustards with "B2W", "B2N" and "D2W" - second and last quarters of 1962. Original circular (domical) footswitch present. The speaker has been replaced.

Serial number 3740

A Twin covered in smooth black vinyl. Black luggage handle. Type of speakers fitted unknown at present.

NEW

Serial number 3753 - single speaker

Chassis assembled by Triumph. In the preamp, Mullard mustards with "A2W" and "B2W" date codes = first and second quarters of 1962. The blue Elac speaker is still in place.

NEW

Serial number in the high 3700s / 3800s - single speaker

Chassis assembled by Westrex. Originally beige (fawn) vinyl. In the preamp, WIMA signal caps. The tone pot has the date code "LJ" = December 1962 for its manufacture. Thanks to James for the info, pictures to follow.

Serial number 3805 - single speaker

Chassis made by Westrex. In the preamp, Mullard mustards with "D2N" = last quarter of 1962. The yellow-print Mullard ECC83 has the paint code "KA" = January 1963.

Updated

Serial number in the 3800s (?)

In the pictures known at present the component date codes of the Mullard mustard caps appear to have been deliberately blurred out. The presence of the "D" in some indicates "D2N" = last quarter of 1962.

NEW

Serial number 3821 - single speaker

Beige (fawn) vinyl. What looks to be the original round footswitch is still present. Blue Elac speaker just visible in the compartment.

Serial number 3842

Cabinet covered in thick finely textured vinyl. Original Elac blue speakers in place. The original metal footswitch (second type with a plain domed top) survives. In the preamp, Mullard mustard caps with "B2N" and "D2N" date codes - second and fourth quarters of 1962 for their manufacture. One of the pots has "KJ" = November 1962. Underchassis, the blue Hunts cap has "IIH" = 33rd week of 1962.

Serial number 3874

Fine condition, but lacking its original speakers. Blue Elacs from some other source have since been fitted. Chassis assembled by Triumph. In the preamp, Mullard mustard capacitors with "B2N", "D2N" and "D2W" date codes - second and last quarters of 1962, assembly of the chassis therefore early 1963.

Serial number 3899

Old pictures, sold a while ago in Chicago. Chassis assembled by Triumph; the original blue Elacs still in place.

Serial number 3937

Cabinet covered in speckled black vinyl. Speakers replaced. Chassis assembled by Triumph. In the preamp, Mullard mustard capacitors with a spread of date codes: "A2N", "B2N", "D2N" and "A3N" = respectively first, second and last quarters of 1962, and first quarter of 1963 for their manufacture. Repaired by Noble of Cardiff in 2000 (sticker inside cabinet).

Serial number in the 3900s (?)

Chassis assembled by Triumph, mains transformer replaced. In the preamp, Mullard mustards with date codes "B4N", "D2W" and "D2N", second and last quarters of 1962. The original Elac blues are still in place, wired in parallel. The cabinet is interesting. Not only is it not sprayed black inside, but there are small sections of runner inside, lower front, to support the baffle between the speakers. Most other cabs have a single length.

Serial number in the 3900s (?)

Black textured vinyl; still the old-style luggage handle. No voltages on the control panel; blue Elac speakers.

AC10 Super Reverb Twins from around this point

Advertised as being new to the JMI range in February 1963. A separate page on the AC10 SRTs will be available soon. The earliest definitively known at present is noted below, serial number 4114.

NEW

Serial number 3937

Textured black vinyl, original handle and vents. In the preamp, Mullard mustards with "A2N", "B2N" and "D4N" date codes - respectively first, second, and last quarters of 1962 for their manufacture. The speakers have been replaced.

Serial number 3943 - single speaker

A single speaker AC10, fawn (beige) vinyl.

Serial number 3966

Cabinet covered in black lightly textured vinyl. Chassis assembled by Westrex. In the preamp, gold-coloured WIMA Tropyfol capacitors and TCC electrolytic caps, one of which has the date code "TM" = December 1962. Chassis probably assembled early to mid 1963. The speakers are replacements - silver Elacs from a Vox PA column.

Serial number 3993 - single speaker

A single speaker AC10, fawn (beige) vinyl. In the preamp, Mullard mustard capacitors with "B2W", "B2N", and "D2W" date codes = second and last quarters of 1962. Single blue 10" Elac 10N/81. The original circular (domical) footswitch is still present.

Serial number 4030 - single speaker

A single speaker AC10, fawn (beige) vinyl. Still the luggage handle and circular (domical) footswitch.

From this point, the new plastic handle.

Serial number 4108

Chassis assembled by Westrex; blue Elac speakers. Note the presence of the new-style plastic handle (superceding the old "luggage" handle). The amp said to be "early 1964". Picture from Jim Elyea, p. 345.

Serial number 4114 - Super Reverb Twin

Serial number 4154

Chassis assembled by Westrex; silver Elac (?) speakers with unusual magnets. The wiring looks original. The fawn vinyl is a later re-covering.

Serial number 4221

At one time in Germany, probably now in the USA. Illustrated in the "Vox Vintage Calendar 2000".

Serial number 4222

Cabinet covered with textured black vinyl. The original blue Elac 10N/81s are still in place.

Serial number 4223

Chassis assembled by Westrex. There are no numbered voltages on the panel around the selector.

Serial number in the 4000s

Chassis assembled by Westrex. Albion transformers. In the preamp, a TCC capacitor with the date code "UG" = July 1963, and the main preamp filter "TYI" = 40th week of 1963. Note the "Vox Sound Equipment Limited" labels on the blue Elac speakers. The amp's cabinet is covered in lightly textured black vinyl.

Serial number 4231

Serial number 4250 N

Thin-edged cabinet; textured black vinyl; new style plastic handle; blue Elac 10N/81 speakers. In the preamp, the gold-coloured TCC 25uf capacitors have the date code "UG" = July 1963.

Serial number 4298

Serial number 4302

Serial number unknown

Pictures unfortunately too small to make out the number. Shiny textured vinyl; brass vents' new-style plastic handle.

Serial number unknown

Repaired by Alan Pyne, a former JMI engineer, who set up in business at 119 Dartford Road following the collapse of Tom Jennings's post-JMI company "Jennings Electronic Industries" in 1975/1976. Thin-edged cabinet; textured vinyl; new-style plastic handle; blue Elac speakers. Fitted inside the cabinet at top on one side, a large mains socket.

Basketweave covering the norm from this point

Still the thin-edged cabinet