Vox AC30: grey panels, Celestion silvers

Late 1965 through to 1967: serial numbers in the 20000s and 21000s

Woden transformer, date code "DX" = April 1966, in serial number 21019.

This page picks up from the page on AC30s with .

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".

In late 1965 production began to slow. The European market was still strong, but fewer orders for AC30s came in from America. The Thomas Organ Company, which had the rights to the "Vox" name in the States, preferred to promote its solid state range.

The four models are still: "TB" for "Top Boost", designated "TB" on the serial number plate, the circuit's controls normally integral in the control panel; "Treble" designated with a "T"; and "B" for Bass. The two last had their own schematics, in order: OS/056, OS/065 and OS/057. "Normal" voicing no longer seems to be an active designation. Some notes on the treble circuit, which was new in 1964, can be found .

Number plates with three lines - MODEL No., SERIAL No.. and RATING (power consumption) - come in in the high 20000s. Chassis numbers are now stamped on the aluminium preamp upright underneath the input jacks rather than under the voltage selector.

Around a third of the way into the 21000s, a new style of control panel comes in, 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 21397, see further below.

Woden transformers are the norm, year codes being "V" = 1964, "W" = 1965, and "X" = 1966, the first letter in the two-letter sequence standing for the month: "DX" = April 1966 for instance. A large batch of Wodens was evidently ordered in Spring 1966 - examples dated "DX" are found well into 1967. See also the page on .

Duriing the course of 1966, white 1/4 watt Erie resistors began to be used again instead of the brown Dubiliers.

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 single pins through to the low 21000s. Thereafter double pins come in. But as ever there is no sharp transition.

Note that the majority of serial numbers of amplifiers in the range 20000-21000 cited by Jim Elyea - listed in his book and noted on this page - end in "0". How can this be? The suspicion is that at least some of these are simply placeholders and guesses: i.e. "serial number 21410 will have been reached at June 1966".

If anyone knows of further amps that should be incorporated on this page, .

Serial numbers in the 20000s

Serial number 20017 TB - currently in the UK

Top boost in panel. A number of replaced control knobs. No shots of the electronics at present.

Below, pictures of the serial number plate sold separately in 2022, probably indicating that the amp has been parted out.

Serial number 20139 TB

Grey panel, integral Top Boost. Chassis number in the 11000s - 11998 (?) Albion mains transformer; Woden output date code "EW" = May 1965; gold-coloured choke (as used in AC100s) stamped 66429. In the preamp, Mullard caps with date code "B4N" and "C4N" = second and third quarters of 1964.

Serial number 20150

Listed by Jim Elyea, but probably in the abstract (i.e. no details of component date codes known or even of the amp's existence).

Serial number 20269 TB

Chassis number, stamped under the voltage selector, not quite readable. Transformers are Woden and Albion. The Woden (output) has the date code "KV" = October 1964. The choke (part no. 66429) is of the type used in certain fixed bias AC100s. In the preamp, a mixture of Mullard mustards, a number with "B4N" and "C4N" (= second and third quarters of 1964), and gold-coloured WIMA Tropyfoil (Tropyfol). Two of the TCC cathode bypass caps have "WC" = March 1965.

Serial number 20370 TB - currently in the UK

The serial number plate alone, sold on ebay in the UK in November 2021.

Serial number 20400

Listed by Jim Elyea, but probably in the abstract (i.e. no details of component date codes known or even of the amp's existence).

Serial number 20442 TB - currently in Europe

Chassis number 12140. The preamp has a mixture of Mullard mustard and WIMA capacitors. No date codes visible.

Serial number 20447 TB

Possibly Woden transformers. One of the Celestion silvers has the date code "17HK" = 17th August 1965.

Serial number unknown - currently in Europe

Chassis number 12344. Chassis and speakers in a later cabinet. Woden output transformer "HW" = August 1965, mains transformer "JW" = September '65. A number of Mullard mustard capacitors have the date codes "B4N" and "C4N" = second and third quarter of 1964 for their manufacture. One - a later addition - gives C/71 (third quarter of 1971). The Celestion T1088s have the date code "11KK" = 11th October, 1965. The cabinet, covered in basketweave, has two lines of vents (ie. six in total), and probably belonged originally to an amp made at the Birch-Stolec factory in the early 1970s. Note the gap between the chassis and the top edge of the case. Thanks to Paul for the pictures.

Serial number 20523 TB - currently in Scandinavia

Voltage selector removed in conformity with Scandinavian electrical regulations. The Woden transformers have date codes "KV" and "JW" = October 1964 and September 1965. The stamping on the mains transformers has part of the old component code "J.82". The choke is of the type used in early fixed bias AC100s, part number "66429".

Serial number 20557 TB - currently in Scandinavia

Probably exported to Denmark early on. Voltage selector removed and a plaque fixed over the empty hole. The Celestion blues are likely to be later replacements.

Serial number 20565

Existence recorded by Jim Elyea

Serial number 20675

Existence recorded by Jim Elyea

Serial number 20703 TB

The Woden mains and output transformers have the date code "KV" = October 1964. The choke has "BW" = February 1965. One of the silver speakers is a later replacement. The original cover is still present.

Serial number 20750 TB

Thanks to Keith, photos of serial number 20750, bought in Queensland (Australia) in 1975. The Woden output transformer and choke have the date code "MW" = December 1965, the mains transformer "HW" = August '65. Preamp in good order. Speakers are now early Celestion greenbacks (Thames Ditton Works). In company with the serial number plate on the back panel, a JMI speaker unit plate.

Serial number 20770

Existence recorded by Jim Elyea

Serial number 20831 TB - currently in Europe

Plate on an AC30 TB Super Twin.

Serial number 20833 TB - currently in the UK

Serial number 20840

Listed by Jim Elyea, but probably as a "guesstimate".

Serial number 20899 TB

Woden transformers (date codes unknown) and gold-coloured choke stamped 66429. The serial number is in the new position - on the left hand side of the chassis (under the input jacks). The original JMI warranty documentation and owner's manual are still present. Speakers are Celestion T1088s, the terminals still on the frame (rather than an intermediate board).

Serial number 20910

Listed by Jim Elyea, but probably as a "guesstimate".

Serial number 20965

Listed by Jim Elyea, but probably as a "guesstimate".

Serial number 20983 TB

No shots of the electronics. On the front of the grille cloth, the "TOP BOOST 30" runner is still present. Speakers are Celestion T1088s, terminals on the frames.

Serial numbers in the 21000s

Serial number 21019 TB

Chassis number 14021. The Woden transformers have the date code "DX" = April 1966. In the preamp a mixture of Mullard mustard and WIMA caps. Some of the date codes on the former can be seen - mostly B4N = second quarter of 1964, a large number evidently having been ordered in early '64. The gold-coloured choke (part no. 66429) is of the type found in certain AC100s. The Celestions are of the earlier type with termainals on the frame, rather than on a discrete terminal board.

Serial number 21051 T

No shots of the electronics. Three-line serial number plates. The Celestion T1088s have terminals on the frame (i.e. not new style).

Serial number 21056

Chassis number 12943 stamped on the left side of the preamp. Woden mains transformer with date code "EW" = May 1965; output with "HW" = August 1965. A mixture of Mullard mustard and WIMA caps. Cabinet produced by "Gla-Rev", its white stamp (stencil) inside. The back-boards have square rather than radiused corners. Speaker terminals on the frames (as serial number 21051 above).

Serial number 21075

Existence recorded by Jim Elyea

Serial number 21086 - currently in Corsica

Chassis number 12962. The Woden mains and output transformers have the date code "HW" = August 1965; choke "DX" = April 1966. The silver alnicos (T1088s), terminals on the spokes of the frame, have "15DK" and "18HK" = 15th and 18th April 1965. The mustard capacitors in the preamp have "A4N", "B4N" and A5W", respectively first and second quarters of 1964, and first quarter of 1965. Thanks to Philippe for the pictures and details.

Serial number 21098 TB

In good external order. Exported to Sweden early on - the voltage selector removed (to conform with Scandinavian electrical regulations) and a plate to cover the resulting hole. Woden transformers, the output with date code "KV" = October 1964; the choke with "AX" = January 1966; and the mains transformer with "HW" = August 1965.

Serial number 21126 TB

Chassis serial number in the 7000s - probably 07581, so likely to have been removed from another amp. Albion transformers. Still the old-style JMI logo on the control panel. An original hand-stamped serial number plate. The speakers have been replaced.

Serial number 21190

Listed by Jim Elyea, but probably as a "guesstimate".

Serial number 21192 - currently in the USA

The Woden transformers and choke have the date code "DX" = April 1966. In the preamp, WIMA and Mullard mustard capacitors (some of the latter with date code "A4W" = first quarter of 1964). The Celestion silvers still have terminals on the frame (rather than on boards). Thanks to Jarod for the pictures.

Serial number 21300

Listed by Jim Elyea, but probably as a "guesstimate".

Serial number 21304

An earlier chassis assembled by Westrex slipped into the box in recent years. The speakers, with terminal boards between the struts, are original to the box (1966).

Serial number 21306

The serial number plate alone sold on ebay in the UK (February 2022)

Serial number 21397 TB - currently in Sweden

Probably exported early on to Sweden, where the voltage selector was removed (to conform with local electrical regulations). Mains transformer replaced. The Woden choke has the date code "BX" = February 1966. Red and yellow Lemco signal capacitors in the preamp. The blue Hunts cathode bypass capacitor in the power section has the date code "UYU" = 6th week of 1966.

Serial number 21410

Listed by Jim Elyea, but probably as a "guesstimate".

Serial number 21418 TB

The earliest instance so far (March 2023) of the new-style JMI logo on the control panel.

Serial number 21520

Listed by Jim Elyea, but probably as a "guesstimate".

NEW

Serial number 21581 TB - currently in Europe

Woden transformers with date codes "JX" and "LX" = September and November 1966. In the preamp, red Lemco signal caps. The main preamp filter - made by CCL - has the date "L6" = December 1966. The logo is a 1980s replacement.

NEW

Serial number 21608 TB - currently in Germany

Thanks to Stefan for the pic.

Serial number 21630

Listed by Jim Elyea, but probably as a "guesstimate".

Serial number 21662 TB

New-style JMI logo on the control panel. The Woden transformers have the date code "GX" = July 1966. In the preamp, red and yellow (0.1uf) Lemco capacitors; Hunts electrolytics with date code "WAU" = 19th week of 1966. The terminals of the Celestion T1088s are on boards rather than on the frame. The "TOP BOOST 30" runner is still on the front grille.

Serial number 21693 TB

New-style JMI logo on the control panel.

NEW

Serial number 21694 TB - currently in Germany

Chassis number 13448. Thanks to J├╝rgen for the pics.

Serial number 21740

Listed by Jim Elyea, but probably as a "guesstimate".

Serial number 21850

Listed by Jim Elyea, but probably as a "guesstimate".

Serial number 21884 TB

The Woden output transformer and choke have the date code "HY" = August 1967. Mains transformer replaced. The control panel is of the new style with "JMI" as separate letters on separate backgrounds. In the preamp Mullard mustard and red Lemco capacitors.

Serial number 21945 TB

"TOP BOOST 30" runner on the grille cloth (lower right). The Celestion T1088 speakers have terminals on boards.

Serial number 21960

Listed by Jim Elyea, but probably as a "guesstimate".

Serial numbers unknown

Serial number in the 20000s (?) - currently in the UK

Chassis number 12403. The serial number plate is a reproduction. Grey panel, integral Top Boost controls. The Celestions have the date code "01FJ" = 1st June 1964.

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