The preamp of serial number 22177. Note the red Lemco capacitors.

This page picks up from the page on AC30s with serial numbers in the 20000s and 21000s.

Control panels are grey. Dome voltage selectors occur as standard, as they are for amps with serial number in the 17000s and later. Chassis were assembled by Burndept, the contract with Westrex having ended in early 1965 following JMI's move (expansion) into Burndept's West Street Factory in Erith - the "West Street Works".

During the course of 1967 and 1968, JMI's main drive was the new fully solid state range, finally released in March/April 1967. A reasonable number of valve amps were still offered, though they were no longer centre stage. A large proportion of late JMI AC30s were exported to the continent - particularly Scandinavia, the Netherlands, Germany, and Italy.

Page from the JMI solid state catalogue of March / April 1967.

A detail from the JMI Retail Price List of April 1967.

The models formally offered are the: AC30 Twin "Normal", "Bass", and "Treble Boost", this last designated "TB" on the serial number plate, the circuit's controls normally integral in the control panel; the AC30 Super Twin (separate amplifier section and speaker cabinet) "Treble Boost" and "Bass"; and the AC30 Super Twin Reverb.

The "Treble" version of the AC30 Twin (circuit diagram OS/056) is no longer listed. There is currently no instance among the amps below of a serial number plate with the designation "T".

Number plates with three lines - MODEL No., SERIAL No.. and RATING (power consumption) - were first introduced in the high 20000s and remained the norm through to around number 22700. Thereafter for a short time the two-line plate returns, generally hand-stamped (both the model designation and the serial number itself).

In very late 1967 / 1968, probably corresponding with the collapse of Royston Industries (which controlled JMI) and the appointment of an official receiver to oversee JMI's financial affairs, a new style of plate was brought in (also used for Vox AC50s) - headed "AMPLIFIER" rather than "VOX AMPLIFIER" also with two lines rather than three.

Chassis numbers continue to be stamped on the aluminium preamp upright underneath the input jacks rather than under the voltage selector.

Control panels are normally of the type that first came in half-way into the 21000s, the JMI logo presented as separate letters on separate parallelogram backgrounds (as on the copper amps) rather than as a single block that runs into the silver bounding lines.

The earliest amp on which this new type of panel has come to light is serial number 21418.

Woden transformers are the norm. Date of manufacture is indicated by two letters. The second is the year: "X" = 1966, "Y" = 1967, and "Z" = 1968. The first letter is the month (A-H, J-M). "JX" = September 1966 for instance. The batches in view for the most part have codes "JX", "KX", and "LX" = September-November. See also the page on later AC30 Super Twins.

Celestion silver alnicos - the T1088 - are standard. In mid 1966 a revised version comes in with a terminal board between the spokes of the frame. Earlier T1088s have terminals on the frame itself. Grille cloth is normally black. Plastic corner protectors have double pins.

In late 1967 / early 1968, the logo traditionally used on AC30s was replaced on some amps (not all though) by the new-style version first adopted for the fully solid state amplifiers. Late JMI AC50s also have this new-style logo.

Note that the catalogue printed for the German market in March 1968 still has an amp with the old-style logo. Pages on documents 1967 and 1968 will be available shortly.

Note that all the serial numbers of AC30s in the range 22000 cited by Jim Elyea - listed in his book (p. 539) - end in "0". These are likely simply to be "guesstimates", ie. serial number xxxxx is likely to have been reached by such-and-such a date. They have not been included below.

If anyone knows of further amps that should be incorporated on this page, do let me know.

Serial number 22029 TB - currently in Germany

The Woden transformers and choke have the date code "KX" = September 1966. Top Boost controls are in panel (the standard arrangement). Celestion silvers with terminals on boards between the spokes of the frame.

Serial number 22050 TB

Chassis number 14032. In the preamp, red Lemco capacitors and Dubilier solid polyester (yellow as used in the Vox solid state range of amplifiers). Speaker terminals on boards rather than the metal frame.

Serial number 22053 TB

The hang-tag, and envelope for the guarantee documentation of the amp, noting its voicing.

Serial number 22112 TB - currently in Scandinavia

Just the box and its serial number plate. The chassis and speakers are from a later VSL AC30.

Serial number 22117 TB - currently in the UK

Owned by Dave Davies of The Kinks probably from new until 2007. Sold on ebay in May 2007.

Serial number 22177 TB - currently in Germany

Superb original condition. The Woden transformers and choke have date codes "JX", "KX" and "LX" = September, October and November, 1966. THe blue Hunts/Erie bypass caps in the preamp have "UWY" = 1966, 10th week. The red CCL filter cap has "L6" = December 1966. The amp is currently (Feb. 2021) on ebay.de.

Serial number 22203 TB

Mains transformer replaced. The Woden output transformer and choke have the date codes "KX" and "LX" = September and November 1966. Most of the Vib-Trem circuitry has been removed.

Serial number 22228 TB

Woden transformers with date code "LX" = November 1966. The blue Hunts electrolytics have "UWY" = 1st week of 1966. In the preamp, yellow and yellow and blue Dubilier polyester capacitors and red Lemcos. The main preamp filter cap - made by CCL - has the date code "L6" = December 1966.

Serial number 22235 TB

Woden output transformer and choke with have "KX" = October 1966. The mains transformer and Celestion blues are later replacements.

Serial number 22250 TB

Exported to Scandinavia early on, the voltage selector removed (required modifications also made internally). Voltage selector removed and red warning plaque in Swedish added beneath the serial number plate.

Serial number 22300 TB

Chassis number 14395. The Woden transformers have the date code "LX" = November 1966. In the preamp, the main CCL filter cap has "L6" = December 1966.

Serial number 22393 TB

Exported to Scandinavia early on. Voltage selector removed in accordance with local electrical legislation. Ancillary fuses for the main HT lines were also a requirement. Imported by "Muskantor and Co. AG" in Goteborg, one of JMI's main regional agents.

Serial number 22397 TB

Chassis number 14423. The Woden mains transformer has the date code "JX" = September 1966, the choke "MX" = December 1966. In the preamp the main filter cap (made by CCL) has "L6" = December 1966; Dubilier and red Lemco caps throughout. What may be the original Tungsram EL84s survive.

Serial number 223xx TB

Serial number 22400 TB - currently in Germany

Voltage selector removed by the dealer / importer. One of the Celestion silvers is of the older type (terminals on the frame), the other of the new (terminals on a board between the frame spokes).

Serial number 22409 TB

Serial number 22461 B

Only pics of the serial number plate for the time being. A relatively rare instance of a late "Bass" model.

Serial number 22480 TB - currently in the USA

Woden mains and output transformers have "KX" and "LX" = September and October 1966. Red Lemco capacitors in the preamp. The main preamp filter cap has the date code "VH" = August 1966. Celestion silvers are of the later type (post mid-1966) with terminals on boards. The amp is currently on Reverb.

Serial number 22689 TB

Machine-stamped serial number plate.

Hand-stamped serial number plates for a time from this point

Serial number 22765 TB

Chassis number 14821, assembled by Burndept. Hand-stamped serial number plate. Woden transformers with "KY" date codes = October 1967. Thanks to Luca for the pictures.

Serial number 22789 TB

Chassis number 14889. Hand-stamped serial number plate. Excellent condition and complete with inspection tag (8th December, 1967); booklets; and sales slip (June 1968). The "Operation and Maintenance" booklet is from a slightly later period. Thanks to Tom for kind permission to post the pictures here.

Serial number 22803 TB

Chassis number 14851. New American-style logo; grille cloth renewed. Hand-stamped serial number plate. Mullard mustard capacitors in the preamp, some with "D4N" date codes = last quarter of 1964.

Machine-stamped serial numbers again

Serial number 22841 TB

Woden transformers with date code "KY" = October 1967. The choke is of the type found in AC100s, gold-coloured, stamped "66429". Mullard mustard caps in the preamp have "D4N" and "D6N" date codes - respectively last quarters of 1964 and 1966.

Serial number 22847 - currently in Italy

One of last AC30s produced with a JMI serial number plate with "Vox Amplifier" at its head; perhaps sold by "Vox Sound Equipment Limited" - the company that succeeded JMI - in the summer of 1968.

NEW

Serial number 22854 TB

Horizontal "solid state" format logo. Currently in Germany (Oct. 2023) as many late JMI AC30s are. Original speakers still in place. The original cover also survives. Some later sockets added on the back panel.

From this point, the main heading on serial number plates is "AMPLIFIER" rather than "VOX AMPLIFIER". In mid December 1967, JMI went into receivership and was evidently no longer able to use the old-style plates.

NEW

Serial number 22949

Horizontal "solid state" VOX logo. Reasonable external condition. A small hole present in the upper back board at right. The original silver T1088s still in place. In the preamp, mainly Mullard mustard capacitors. The main TCC filter capacitor has the date code "YM" = December 1967.

NEW

Serial number 22973 TB - currently in Europe

In good external order. Original silver T1088s still in place. A couple of jack sockets added on the lower back panel.

Serial number 22976 TB - currently in Europe

Excellent condition all round and complete with original cover. The logo is of the type used on solid state amps (also as serial number 22847). The Woden output transformer has the date code "BZ" = February 1968. The mains was replaced at some stage. The yellow Dubilier filter cap has the date code "YL" = December 1967. Thanks to Nick for the pictures.

Serial numbers in the 23000s

Serial number 23010 - currently in Europe

Superb condition. A mixture of red Lemco and Mullard mustard capacitors in the preamp. Visible date codes of the latter are "D7N" = last quarter of 1967. Two-line serial number plate headed "AMPLIFIER". The amp is currently on Reverb.

Note that AC30 Super Twin serial number 5596 has Woden transformers dated February and March 1968. The amp is likely to have been assembled shortly before JMI ceased trading in the late spring of that year.

Serial numbers unknown

Serial number unknown - 22000s

Top Boost. The Woden output transformer has "KY" = September 1967. In the preamp, a mixture of red Lemcos and Mullard mustard capacitors. The number plate is the standard three-line version, headed "VOX AMPLIFIER".

On to AC30s assembled in Italy, 1968-1972.