The new split-front single speaker AC10 - its front part grille cloth, part vinyl-covered - was introduced by JMI in early 1961. The earliest amps had black control panels and brown or black circular knobs (rather than "chicken-heads").

In January 1961, its price remained 45 guineas - no change from TV Front days:

JMI prices, January 1961.

The two-input AC10 at 35 guineas was a more basic model - in more recent times termed the AC10 "Throwback" - with tremolo controls on its back panel. Further information on this model can be found on this page.

JMI brochure from Spring 1961.

In late 1961 the four-input single speaker AC10 was joined by the AC10 Twin and the two-input "Throwback" phased out. Anecdotal evidence suggests however that a few Throwbacks may have been made in early '62.

The principal members of JMI's range of amplifiers, including the Twin, were shown at the Russell Hotel Trade Fair in August 1962 and illustrated in the flyer printed to accompany the show. This as it turned out was the first public showing of the Twin, as there had been no Fair in 1961 - manufacturers were left to their own devices.

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

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.

Advert in a JMI brochure of late 1963.

In mid 1964, the price of the single speaker AC10 went up to 47 guineas, that of the Twin to 57 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).

JMI dealer catalogue of 1964, the various species of AC10.

During the course of 1965 the single speaker AC10 was phased out, presumably as a result of dwindling sales. It appears in the official JMI pricelist of May '65, but is absent from the November list. A primary factor in the decline of the model was probably Thomas Organ's creation of its own range of smaller amps. The complexion of exports to the USA, big news in August 1964, had changed.

Production / assembly (early 1961 to early 1965)

For the most part the black panel AC10 chassis of the first half of 1961 were assembled for JMI under contract by Westrex in North London. In the latter part of 1961 however, assembly of the AC10 was handed over to Triumph Electronics in Purley. A key factor in this move was the advent of the AC10 Twin, which had exactly the same electronics as the single speaker AC10 - so potentially twice as many chassis required, increasing in number month by month as sales picked up. So far as one can tell, Westrex, a hugely diversified company, did not have the scope to expand production at this time.

Final assembly of the amps - the bringing together of chassis, cabinet, and speakers - took place at Dartford Road. Below, a shot of an AC10 Twin just off the assembly benches, late August 1964:

Thanks to Robert Valentine, who worked at JMI from late 1959 to late 1964.

Note that the amp in the picture above has no serial number plate. Following final assembly, amps were put to one side to await final checking and testing - normally a "play" test with the designated instrument (normally guitar). Only then was a serial number assigned and plate affixed. Numbers were entered by Jack Jennings in his registers. This at least was standard procedure in the days of hand-stamped plates.

The lowest serial number definitively known for a split-front single speaker AC10 at present is 3433 - see the overview of surviving amps further down this page - its chassis (with black panel) assembled in early 1961. Quite how many amps amps with black panels followed is unknown at present - certainly no more than 40 however.

The rule as it stands seems to be copper from late 1961, then grey later on (from mid 1964). On the types of panel used at various points in production, see Glen Lambert's page - Vox AC10 control panels.

In contrast to Twins, the majority of single speaker AC10s issued in the period 1961 to 1963 were covered in beige (fawn) vinyl. The thick smooth black covering - a sort of "Morocco" - often found on early Twins was used only occasionally. By the time we come to serial numbers in the 4300s, basketweave becomes commonplace.

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. 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 - perhaps part of the reason for the increase in price of both the single speaker AC10 and Twin at this time. 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 again 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; and Triumph in any case had been tasked with other things, not least the development and production of JMI's range of PA amps, and in late 1963, production of the AC50, which constituted the greater part of the company's work for Jennings through to 1965.

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.

In mid 1964 (serial numbers in the 4500s), AC10 Twins were split off into a new serial number sequence beginning at number 1000. The existing sequence was retained for single speaker AC10s alone. At this point, new thick-edged cabinets were introduced for both models.

Covers

Covers were generally made of "plasti-leather" and came in four main colours: burgundy, red, green, and dark brown. So far as survivals are concerned, russet and red seem to have been the most common.

Single speaker AC10 cover from early 1964.

Later 1964.

An overview of surviving split-front single speaker AC10s

Entries for AC10 Twins are given principally for orientation and comparative purposes (where component date codes are known and useful, for instance). As mentioned, 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.

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

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.

"Throwbacks"

That batches of split-front two-input AC10 "Throwbacks" were produced at around this time is clear from survivals: serial numbers 3430, 3431, and 3460. Another two have lost their plates.

Serial number 3496

AC10 single speaker, split front cabinet, copper panel. Goodmans speaker with red magnet (as in the Twin pictured below). Late 1961 (?). Sold on ebay in 2007.

Serial number high 3400s / low 3500s - twin

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 - twin

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 (the speaker now replaced with a blue Elac). 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 - twin

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 N

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 N

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 - twin

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

Serial number 3643 - twin

NEW

Serial number 3679

A single-speaker AC10, beige/fawn vinyl. Visible Mullard mustards have "A2N" and "B2N" date codes = first and second quarters for their manufacture. Original dome footswitch is present; the speaker is now an Eminence. Some handle other than the one currently on the amp was once attached.

Serial number 3689 - twin

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 - twin

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

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 belong to AC10 Twin serial number 3689 (noted above). Some chassis were made by Westrex (serial number 3805).

Serial number 3724

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 for their manufacture. Original circular (domical) footswitch present. The speaker has been replaced.

Serial number 3740 - twin

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

Serial number 3753

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.

Updated

Serial number in the high 3700s / 3800s

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

Chassis assembled 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. Blue Elac 10N/81, original green and yellow wiring in place.

Serial number in the 3800s (?) - twin

Chassis assembled by Triumph. The component date codes in the pictures known at present seem to have been deliberately blurred out. The presence of a "D" on at least one of the Mullard mustards indicates "D2N" = last quarter of 1962 for its manufacture.

Serial number 3821

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 - twin

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 - twin

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.

Updated

Serial number 3881

Fawn covering, brown grille cloth. Formerly owned by Rory Gallagher (bona fide provenance). Auctioned at Bonhams in October 2024.

Serial number 3899 - twin

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

Serial number 3937 - twin

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 (?) - twin

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 (?) - twin

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.

Serial number 3943

A single speaker AC10, fawn (beige) vinyl. Replaced speaker. A lighter coloured control panel, as serial number 3966 below. No shots of the electronics at present.

Serial number 3966 - twin

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

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

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 - twin

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 - twin

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 - twin

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

Serial number 4222 - twin

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

Serial number 4223 - twin

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

Serial number in the 4000s - twin

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 - twin

Serial number 4250 N - twin

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 - twin

Serial number 4302 - twin

Serial number unknown - twin

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

Serial number unknown - twin

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

Serial number unknown - twin

Sold some time ago. Thin-edged cabinet; basketweave vinyl; new-style plastic handle; blue Elac speakers.

Serial number 4327 N - twin

Excellent condition. Thin-edged cabinet; basketweave vinyl, new-style plastic handle, original Blue Elac speakers, wired in parallel (not series as initially stated). Currently (August 2023) for sale in Denmark.

Serial number 4358 - Super Reverb Twin

An AC10 Super Reverb Twin.

Serial number unknown - twin

Thin-edged cabinet; basketweave vinyl; new plastic handle. The control panel gives voltages. Blue Elac speakers.

Serial number 4467 N - single speaker.

Basketweave vinyl, brown grille cloth. Original blue Elac speaker still in place.

Serial number 4469 - Super Reverb Twin

An AC10 Super Reverb Twin.

Serial number 4505 - twin

Pictured by J. Elyea, p. 345.

New thick-edged cabinets

Sometime shortly after this point, Twins were split off into a new numerical sequence beginning at 1000. The move to a new thicker-edged cabinet seems to have gone hand in hand with this change. Single speaker AC10s continued to be issued with numbers in the original sequence through to the 4700s.

Serial number 4575 - single speaker

Thick-edged cabinet; black grille cloth; grey control panel. Blue Elac speaker, though the wiring has been altered.

Serial number 4583 - single speaker

Thick-edged cabinet; no corner protectors fitted (no tell-tale holes). Grille cloth now faded to a sort of brown. Grey control panel. The speaker now is an earlier Goodmans 10"

Serial number 4594

A single speaker AC10, probably late 1964. Thick-edged cabinet; the speaker is a blue Elac. Thanks to James for the picture.

Serial number 4619

A single speaker AC10, probably early 1965. Transformers are Parmekos, electrolytic capacitors blue Hunts, and signal capacitors Mullards. Hunts date codes are "HWT" and "TIT" = 21st and 41st weeks of 1964; and Mullard "B4N", "C4N", and "D4N", respectively second, third, and last quarters of 1964. Visible date codes on the valves are - EZ81 paint code "LC" = March 1964; EF86 paint code "LE" = May 1964; and on the ECC83 paint code "M?" = some month in 1965.

Thanks to Piers, extensive coverage of the amp can be found on this page.

Serial number 4620

Now (autumn (autumn 2024) known to survive. The panel of this amp is copper. Thanks to Dave for the info.

Serial number 4632

A single speaker AC10, Albion transformers, only one component date code known at present, a TCC capacitor with "VF" = June 1964. Original egg-shaped footswitch present and correct.

On to the page on AC10s with serial numbers in the new sequence beginning at 1000.

For earlier AC10s see the index page here.