Vox AC30 expanded frequency amplifier (AC30X)


JMI catalogue of early 1964: the first appearance of the expanded AC30.

The "Expanded Frequency" AC30 was an interesting move by JMI - the intention being to produce a sort of heavyweight version of the standard AC30 for organ and guitar. As the cabinets were open backed, the use of the AC30X for bass was evidently not a primary concern.

The chassis of the amplifier was the same size and electronically the same as that of the normal AC30 Twin. Top boost controls were advertised as being in-panel.

The majority of amps were produced in 1964. Note that there is no entry for the AC30 Expanded in the November 1965 pricelist.

"Melody Maker" magazine, 1st February, 1964 - an advert for the AC30 Extended Frequency with 15" speakers.

The speakers in view are 15" Celestion T900 or T1074 in blue, 15 ohms apiece, wired in parallel for a total of 8 ohms. They were given "Heavy Duty" labels by Jennings. In mid 1964, the silver versions came in - the T1109 and T1116.

Towards the middle of 1964, the cabinet for the AC30 Expanded Frequency was used as the template for the large box AC50 speaker cabinet - the two are exactly the same size. Indeed, the plan may originally have been to equip the AC50 cabinets with two 15" speakers rather than two 12" drivers and a Goodmans Midax horn. The two prototype AC50 cabinets that The Beatles had at Stockholm, 28th and 29th July, 1964, certainly had two 15" drivers - on the Vox AC100 website.

Serial numbers at first belong to the same sequence as standard AC30s, beginning around 10400 and running through to the 11000s. Thereafter the AC30X was given its own sequence, beginning at number 500 or 501 - possibly coinciding with the transition to grey control panels.

A series of standard-sized AC30s were also produced with copper panel in-panel top boost controls - serial no. 10384 being a pristine example.

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

Serial number 10457 - currently in Germany

Standard black "basketweave" covering. No integral top boost, so perhaps a substitute chassis. Original Celestion drivers in place.

Serial number 10459 - currently in the USA

Serial number unknown - currently in Europe

Standard black "basketweave" covering. Integral top boost. Original Celestion drivers in place.

Serial number 10471 - whereabouts unknown

Blurry pictures from years ago, but the serial number is legible nonetheless.

Serial number 10672 N - currently in the USA

Pebble charcoal covering. Top boost in panel; original speakers in place. The main preamp filter capacitor has the date code "UG" = August 1963. The transformers are Albions.

Serial number 565 - currently in the USA

Grey control panel. Black basketweave covering. Still brown grille cloth. The speakers have been replaced with ceramic 1970s Goodmans.


Serial number 589 - currently in Europe

Stamped "0589". Grey panel with integral top boost. Still brown grille cloth. The cabinet covering is standard basket-weave vinyl. Speakers are Celestion T1109, sprayed silver.

Serial number unknown - currently in Europe

Probably charcoal pebble covering as on the amp above. in-panel top boost. Logo is over to the right. The cabinet has one blue and one silver Celestion - the silver will be a T1109. The label of the silver is upside down, indicating that it is likely to be a replacement from another source.

Serial number unknown - currently in the UK

Much as the amp above: charcoal pebble covering; logo over to the right; in-panel top boost. The original removable cover survives. One speaker replaced. There was a blazing row about this one on the old VoxTalks forum. A commentator posted to the effect that he bet his bottom dollar the AC30X sounded dreadful. The seller (selling on ebay.uk) found the remark and asked how the commentator could possibly know when he hadn't tried one. Things quickly got heated. Fisticuffs were promised should the two meet.

Serial number unknown - currently in the USA

Sold on ebay in November 2005. Top boost integral in the copper panel.

Serial number unknown - currently in the UK

Excellent condition. Top boost integral in the copper panel. Pebble charcoal covering. Albion transformers. In the power section, an 82 ohm cathode resistor. No "Heavy Duty" labels on the speakers.


Serial number unknown - currently in the UK

Grey panel with integral top boost; link voltage selector. Celestion T1109 speakers.

Serial number unknown - currently in the UK

A strange one, perhaps put together by "Vox Sound Equipment Limited" in 1968 - note the speakers. The grey panel chassis has no in-panel top boost. But the box has brown cloth. The cabinet has a standard black basketweave covering.