"Vox Sound Limited" AC30s - 1971-1973

The Birch-Stolec factory, Hastings

Serial numbers in the 25000s, 26000s, and 1000s

This page picks up the story from the page on the AC30s for "Vox Sound Equipment Limited" (1968-1969) and "Vox Sound Limited" (1970-1973). The amps pictured and discussed below were, in contrast, produced in England and sold by VSL, 1971-1973.

Key to understanding the AC30s in this period is the type of serial number plate used. The plates of the amplifiers assembled at the Birch-Stolec factory in Hastings (and a few perhaps at the Vox Works in Erith before that) have the line: "Manufactured in England":

Serial number plate of Vox AC30 number 25571, produced by Vox Sound Limited, Birch-Stolec factory, 1971

Plate of AC30 TB, serial number 25571.

Plates of this type were used for three serial number ranges: 25000s, 26000s and 1000s.

The 25000s and 26000s are AC30 Top Boosts, 1971 to 1972. The 1000s are AC30 Top Boost Reverbs, 1972 to 1973.

1971 - serial numbers in the 25000s - "old style" chassis

AC30 Top Boost - treble and bass controls on the control panel, along with the tone "cut". On the lower edge, far right: "A VOX Product".

Control panel of Vox AC30 number 25612, produced by Vox Sound Limited, Birch-Stolec factory, 1971

The control panel of AC30 TB serial number 25612.

Note that the input jacks are metal, which is always a good way of spotting these amps if other elements are not pictured.

From serial number 25107 certainly (see below), Lemark transformers are standard, though one occasionally finds old Albions and Haddons (surplus JMI stock). The Lemark part numbers are TT4259 (choke), TT4250 and TT4237, mains and output. "TT" stands for "Twickenhan Transformers", the company's name until mid 1969. Twickenham/Lemark also provided transformers for the solid state amplifiers produced by "Vox Sound Equipment Limited" and "Vox Sound Limited" - on the Vox Supreme website.

The use of Lemark-labelled transformers is a good sign that an amplifier was made in the Birch-Stolec factory on the Ponswood Road Industrial Estate, Hastings (really St-Leonards-on-Sea). VSL, under its new general manager, George Stow - the "Sto" of "Stolec" - moved production there from Erith in the early spring of 1971 - .

Whether amps in the range 25000-25100 also had Lemarks is not known at present:

Lemark mains transformer, Birch Stolec Vox AC30 serial number 25107, produced by Vox Sound Limited, 1971

Lemark mains transformer, serial number 25107.

Tagboards are of the standard type (as used by JMI). Mustard capacitors generally have the date codes "D9" and "B0" = last quarter of 1969, and second quarter of 1970, respectively.

Tagboard of Birch Stolec Vox AC30 serial number 25107, produced by Vox Sound Limited, 1971

Serial number 25107. The Mullard mustard capacitors mostly have "B0" date codes = second quarter of 1970,

The speakers used are for the most part T1088s, occasionally with sand-coloured frames, but generally silver. Labels are old "Vox Sound Equipment Limited" labels up to serial numbers in the mid 25600s. Thereafter no labels were fitted.

Visible Celestion date codes run from "KC26" (26th September 1970) to "GD8" = 8th July 1971.

"Vox Sound Equipment Limited" and "Vox Sound Limited" circuit diagrams for the AC30TB can be .

Late 1971/1972 to 1973 - "new style" chassis, printed circuit boards

By serial number 25943, various changes had been introduced, the most striking being the move to a printed circuit board for the electronics and a new style of chassis.

Vox AC30 new chassis of serial number 25943, Vox Sound Limited, Birch-Stolec factory, 1971 or 1972

The new style chassis from the front. Note the recesses in the plinth and preamp. Valve bases are mounted directly on the printed circuit boards. Serial number 25943.

Vox AC30 printed circuit board of serial number 1126, Vox Sound Limited, Birch-Stolec factory, 1972

A detail of the rear of the preamp circuit board. AC30TBR serial number 1126.

A similar approach had been adopted for the preamp of the Vox V100, released by "Vox Sound Limited" in the spring of 1971.

Vox V100, Vox Sound Limited, Birch-Stolec factory, 1971

"Vox Sound Limited" V100, serial number 1105.

The other changes introduced at this time were: plastic vents (as fitted to the solid state range of amps)in the cabinet top, a single row initially, then later double; a unified control panel for the AC30 Top Boost and the new AC30 Top Boost Reverb. The hole for the Reverb control is blanked off in the Top Boost only model. Circular black knobs with silver tops replace the chickenheads, and the voltage selector is moved onto the preamp upright:

Vox AC30 voltage selector of serial number 1126, Vox Sound Limited, Birch-Stolec factory, 1972

A detail of the voltage selector of AC30TBR serial number 1126.

At this point too, a simplified (and bolder) form of serial number plate was brought in:

New style Vox Sound Limited serial number plate, Vox AC30, Birch-Stolec, 1972

New-style serial number plate. Serial number 26074.

Probably no more than 100 or so AC30 Top Boosts were made with serial numbers in the 26000s.

1972-1973 - serial numbers in the 1000s

AC30 TOP BOOST REVERBS. All have new-style chassis and printed circuit boards. Cabinets have double rows of plastic vents on top and new-style serial number plates. Voltage selectors are inside the chassis.

In terms of Celestion date codes, AC30TBR serial number 1161 has drivers with "JE28" = 28th August 1972.

To judge from the serial number plate below, the Birch-Stolec factory produced something over 200 AC30 Top Boost Reverbs before "Vox Sound Limited" folded in early 1973:

Plate of serial number 1210.

Below, an overview of surviving amps. If anyone knows of further examples that should be incorporated on this page, .

1971 - serial numbers in the 25000s

AC30 Top Boost only. Cabinets have basketweave vinyl and a double row of thin metal vents on top - early Italian-made amps only had as single row - . Speakers have VSEL labels. Speakers are Celestion T1088s, normally with 1971 date codes, but with old "Vox Sound Equipment Limited" labels.

Serial number 25107

The Mullard mustard capacitors have date codes "D9" and B0" = last quarter of 1969 and second quarter of 1970. The Celestion T1088s (sand-coloured frames) have "CD22" = 22nd March 1971.

Serial number 25119

Serial number 25340

New badge and grille cloth.

Serial number 25416

Celestions with sand-coloured frames, date code "KC26" = 26th September 1970. Mullard mustard caps have "D9" and "B0".

Serial number 25450

Serial number 25560

Serial number 25571

Serial number 25586

Celestions with silver frames have the date code "DD8" = 8th April 1971.

Serial number 25595

Serial number 25612

Mullard mustards with date codes "D9" and "B0". The Celestions have "GD8" = 8th July 1971.

Serial number 25628

Old Haddon transformers. The Mullard mustard capacitors in the preamp have visible date codes "C9" and "D9" = third and last quarter of 1969. The speakers have VSEL labels.

Serial number 25721

One of the Celestions has the date code "GD7" = 7th July 1971.

Serial number 25782

Printed circuit boards and new-style chassis from this point

Serial number 25943

Serial number plate of Vox AC30 number 25571, produced by Vox Sound Limited, 1971

Serial number 26074

1972-1973 - serial numbers in the 10000s

AC30 TOP BOOST REVERBS. Printed circuit boards, new-style chassis. No voltage selector. Cabinets have a a double row of plastic vents. Speakers have VSEL labels.

Serial number 1064

Serial number 1097

Serial number 1101

Serial number 1126

Superb condition. The speakers are later additions.

Serial number 1161

Serial number 1172

Serial number 1210

Currently in the UK. Goodmans red-label ceramic drivers, probably original to the amp.

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