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Vox AC30 website updates

November 2021

29th November

The perspex Selmer Zodiac made for the trade show in Hilversum, October 1966 - see the entry below for 30 September (2) - evidently still existed in the 1980s (and may still exist). The picture below is from this site.

The chassis is chrome-plated, much as the perspex AC30s made for Trade Fairs, 1963-1965.

28th November

Detail from a shot of the Rolling Stones, Battersea Park, 11th May, 1963. One of the two AC30 Twins in black vinyl covering. Both have new-style plastic handles.

This at present is the earliest firmly dated instance of these handles on an AC30, or rather AC30s.

27th November

The search for early, *firmly dated* examples of AC30s with new plastic handles. Below, a detail from a photo taken by Dezo Hoffman on the 20th June 1963. JMI generally supplied Dezo with empty cabinets (no speakers, no chassis) for his shoots. The Beatles did not receive their new AC30s with plastic handles until August.

Perhaps slightly earlier is this photo, taken for JMI in June 1963, a complete amp, latest possible date for the photo, 27th June.

26th November

An AC30 probably with a number in the mid or higher 6000s - difficult to make out the plate accurately though (6600 or 6900?). Chassis assembled by Westrex. Albion transformers. Celestions with "RIC 2TP" codes are also found in serial number 6529N. The main preamp filter cap (TCC) has the date code "UG" = July 1963. Note the green Welwyn resistors in the power section (underchassis). A couple of unusual features - the use of green TCC cathode bypass caps in the preamp (normally one finds blue Hunts or gold-coloured TCCs); and the purple shrouds to the leads of the plate resistors etc. in the power section.

On the cabinet, handles are likely to be replacements. In spite of its very scuffed underside, it is difficult to make out (from pictures alone) any signs of recovering in the upper cabinet. The finger-joints of sides and top can be seen through the rexine.

23rd November

A list of the AC30 Twins with original valves - some or all, as noted below - has now been set up here. Data on Super Twins will be added in a separate section at the end of the page - probably at the end of this week, along with a page on Mullard date codes.

22nd November (2)

Coming shortly, a page listing the AC30s known to survive with some or all of their original valves.

Below, a chassis produced for JMi by Burndept in late 1964, originally with a dome voltage selector. The cathode bypass cap has the date code "VF" = June 1964. The yellow-print Mullard preamp valves have the print date code "LE and "LF" = May and June 1964; and the EL84s have the Mullard manufacture date code "B4B4" = 4th week of February 1964. A partial code can be seen on the GZ34, also indicating 1964.

Just to note that Mullard valves from the early and mid-1960s, both white print and yellow print, have two sets of date codes. The principal code is a four element set for the manufacture of the valve itself. To take the example above - "B4B4" - Blackburn Factory (B); 1964 (4); February (B); 4th week (4).

A two letter paint (or print) date code was often supplied too, the first letter being the year: H = 1960, I = 1961, J = 1962, K = 1963, L = 1964, and so on; the second letter being the month: A = January, etc.

22nd November

A new page has been started on Brimar valve date codes in AC30s, with reference to the tubemaze info site .

At present - ie. very provisionally - the picture seems to be that Burndept installed Brimar valves from late 1962 to mid 1964 on the chassis it made for JMI, then went over to yellow-print Mullards. Westrex generally used yellow-print Mullards. Any adjustments and corrections will be signalled here on the updates page.

A lot of nonsense has been ventured about yellow-print Mullards over the years - that they were "special quality" or issued completely randomly in batches even through to the 1970s (stories of "tins of yellow paint being seen at the Blackburn factory" in such-and-such a year). The best view seems to be that in the early and mid 1960s yellow-print valves were generally (note the qualification) supplied direct to manufacturers of amplifiers and other electronic devices, and that white-print were supplied to re-sellers (shops and so on.)

20th November (2)

Coming up for sale ... somewhere in England ... an early (very early) AC30 Treble - 11066T on the serial number plate, which has "AMPLIFIER" at its head (rather than "VOX AMPLIFIER") much as number 11076. This marks a point in time immediately before the introduction of the dreadful plastic plates. Quite whether the electronics of the amp conform to the Treble circuit diagram remains to be seen.

20th November

AC30 Top Boost, serial number 19225, the model designation in the lower panel of the plate. From the mid 16000s, the voicing (or model type) was normally stamped in the topmost panel. Thanks to Ihor for pointing this amp out.

18th November

A new page has been started on the harmonic drawbar designed for Jennings organs by Derek Underdown and Geoff Harris in 1957. A developed version of the assembly was an integral part of the Vox Continental, late 1962-1970, and the basis of Jennings's assertion of "world patents" for the organ.

Photograph from late 1957.

16th November

A great deal of thought evidently went into this unused JMI design for an amplifier trolley, not to mention the work of producing it. What was it for? It looks too wide for an AC30. Perhaps an AC30 Expanded Frequency with a tray/basket on top for an echo unit? Note the brakes on both sides to stop the unit moving on a flat or sloping stage. JMI normally only provided brakes on trolleys that were intended for amplifiers that put out large amounts of bass. The Expanded Frequency AC30, with its 2x15" speakers, might have been regarded as falling into that category.

On the other hand, there is a chance that it could be for an AC50 Super Twin, separate amplifier and cabinet with 2x15" speakers - but the tray on top does look slightly diminutive for an AC50 amplifier section.

The hand-wheels have the old-style VOX logo in cursive script.

Picture from autumn 1964.

12th November

The registration photos of the new-style tubular AC30 stand, 22nd September, 1964. The wheels are black plastic (made by Shepherd or Rexello), and there are plastic ends to the spurs on the parallel upper bars.

11th November

On the 22nd September 1964, Jennings registered the design of the swivel side-stands for the AC30 with the Patent Office in London, submitting four photos. Also registered at this time were the Foundation Bass speaker cabinet "dolly", the Univox stand (the "gigster"), and a revamped tubular stand for the AC30. AC30 side-stands, however, were already in production in early 1964 - see the foot of this page - and the Univox gigster stand had been available since 1953!

9th November

Local Dartford press, 3rd January, 1964 - some interesting Jennings prizes in the "Write a Song for Joe Brown" competition: a Vox Continental organ for the winner; and for third prize, probably a Vox PA amplifier and microphone.

8th November (2)

Below, pictures of AC30 Super Twin amplifier section serial number 2501N, the lowest number in the new Super Twin sequence to have come to light so far. It is likely that this sequence began at 2500. Beginning at the hundred was certainly the pattern in 7-series and solid state amps.

AC30 Super Twin serial number 2501N. Chassis assembled by Westrex; Albion transformers. Cabinet in thick dark grey vinyl; black vents still in place.

8th November

The page on Jennings's handling of Thomas organs in 1966 and 1967 has been updated. 1966 was pretty much business as usual. Then in 1967, at fairly short notice, JMI and Thomas announced that the arrangement that had been forged in the summer of 1963 had come to an end. From March 1967, Thomas would take on the distribution of its organs in the UK and Europe. An 18-month advertising blitz by Thomas followed. Further material on 1966 and 1967 to come.

7th November

On 28th August 1964, JMI registered its new design for the AC30 Super Twin amplifier section with the Patent Office, much as it had done with the AC30 Twin (yesterday's entry).

There are various things of note in the new design - the chrome supports; the small-format case; the huge handle; the DIN plug on the back panel for the tremolo and (presumably when required) reverb footswitch, which is not pictured; and the Cannon speaker and mains sockets, the latter an LNE-11 (as used on AC50s).

The amp was illustrated in this format in a brochure issued by JMI in September 1964, and in the "Precision in Sound" newspaper-format catalogue of late '64 - but so far no surviving instances of the AC30 Super Twin in this configuration are known.

When it came to production, the size of the case was increased (made taller); a full wrap-over trolley took the place of the chrome supports; the DIN socket and two-button footswitch (whatever its form) was done away with; and a standard handle replaced the gargantuan one initially envisaged.

The idea of a DIN socket for the effects returned, however, in 1966 in the 7-series amps, being taken up subsequently for the solid state range also.

Thanks to Martin K. for the pictures and for suggesting the exploration of the old Patent Office archive.

The new format AC30 Super Twin represented in the "Precision in Sound" newspaper format catalogue of late 1964.

6th November

On the 28th June 1963, JMI registered the design of the AC30 Twin with the Patent Office in London. Below two of the pictures accompanying the company's submission. The reason for registering the design at this point was probably the provision of the new plastic handles. Note the presence of the brass vents and the absence of corner protectors on the cabinet.

But was this also a first try-out - a very early one - for black diamond cloth? Impossible to say for certain though from a black and white photograph.

Black cloth was formally previewed at the Russell Hotel Trade Show in August 1964 - "a new look for Vox amplifiers".

Further archival pictures to come.