"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 assembled in Italy, 1969-1972 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":
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".
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" - see this page 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 - see this page.
Whether amps in the range 25000-25100 also had Lemarks is not known at present:
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.
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 found on this page.
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.
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.
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 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:
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 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.
Speakers are generally Celestion alnico T2056s without end bells. In terms of date codes, AC30TBR serial numbers 1094 and 1161 have drivers with "JE28" = 28th September 1972. Serial number 1151 has T1088s with "JE25" = 25th September '72.
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, do let me know.
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 - see this page. 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 25210
Albion transformers. In the preamp, visible date codes on the Mullard mustard capacitors are "C9" and "D9" = third and last quarters of 1969. The Celestion T1088s (with sand-coloured frames) have the date code "JC28" = 28th September 1970. The original Mullard EL84s are still in place. Thanks to Chris for the pictures.
Serial number 25299
In the preamp, the Mullard mustard capacitors have date codes "C9", "D9" and "A0" = respectively third and last quarters of 1969, and first quarter of 1970. The silver Celestion T1088s have "GC22" date codes = 22nd July 1970.
Serial number 25332
The plate alone, the amp - chassis, speakers, cabinet - probably resold as parts.
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 25537
Currently in Germany. Some renewed components in the preamp. Celestion T1088s with sand-coloured frames - date code too indistinct (only the day number - 22nd - is visible in pictures).
Serial number 25560
Serial number 25571
Serial number 25586
In the preamp, Mullard mustard capacitors with date codes "D9", "A0" and "B0", respectively last quarter of 1969 and first and second quarters of 1970 for their manufacture. The Celestion T1088s 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 25672
Transformers are Lemark. In the preamp, visible Mullard mustard caps have date codes "A0W" and "BO" = first and second quarters of 1970 respectively. The Celestion T1088s have date codes "DD8" and "DD9" = 8th and 9th April 1971. Thanks to Robert for the pictures.
Serial number 25712
As above, transformers are Lemark (mains has been renewed). In the preamp. the Mullard mustard caps have date codes "D9W", "A0" and "B0" = last quarter of 1969, and first and second quarters of 1970. The pairs of vents on top of the box have been widened to form three single openings large enough for a plastic vent. Speakers are Goodmans heavy-duty ceramic - possibly fitted at factory. Numbers of Defiant and Supreme cabinets assembled in the Birch-Stolec factory were certainly fitted with them. Thanks to Robert for the pictures.
Serial number 25721
One of the Celestions has the date code "GD7" = 7th July 1971.
Serial number 25782
Serial number 25881
Still the old-style serial number plate. Cabinet with six small metal vents. Speakers are now a pair of Celestion G12-100s.
Printed circuit boards and new-style chassis from this point
Two types of printed circuit board were devised in 1972 at the Birch-Stolec factory - one for a small number of plain Top Boost AC30s (thick traces on the board, no board number), and one for the Top Boost Reverbs (thin traces, board numbered "PCB 70-1").
AC30 Top Boost board. Note the thickness of the traces. Relatively few plain AC30 Top Boost amps were produced with PCBs.
AC30 Top Boost Reverb board. Comparatively thin traces, and the printed part code "PCB 70-1".
Presumably as a cost-saving measure, a number of AC30 Top Boost Reverbs were evidently built as simple Top Boosts, the hole for the reverb pot stopped up (and the reverb tank omitted).
Cabinets have six wide plastic vents instead of the narrow metal ones. Also new at this point, a revised style of serial number plate with bolder capitals.
Serial number 25924
The earliest instance of the new-style serial number plate. Although no pictures are available at present, the amp presumably has printed circuit boards.
Serial number 25933
AC30 Top Boost Reverb. Printed circuit board. Speakers are Celestion T2056 alnicos. Mains and speaker sockets added later on the back panel.
Serial number 25943
Serial number 25949
Serial number 25952
Excellent condition. Bought secondhand in Hastings in 1974/1975. The Celestion T2056s have the date code "AF18" = 18th January 1973. Thanks to Dan for the pictures.
Serial number 26019
"Vox Sound Limited" AC30 serial number 26019, made in the Birch-Stolec factory in Hastings, purchased in 1972. Although there is an "Top Boost 30 Reverb" flag on the front (lower right), the amp is actually just a Top Boost. The small board for the input jacks is "PCB72B/3". Speakers are the original Goodman Audiom Power Range, red label. Thanks to Mark for the pictures.
Serial number 26074
Designated on the front runner as an AC30 Top Boost Reverb, but the hole for the reverb pot is stopped up and the serial number plate gives "TB" only. The speakers are Celestion alnico T2056s, still with their original VOX stickers.
1972-1973 - serial numbers in the 1000s
AC30 TOP BOOST REVERBS. Printed circuit boards, new-style chassis. No voltage selector. Cabinets have a a double row of plastic vents. Speakers still have VSEL labels. The circuit diagram is OS/249, drawn out on 30th May 1972.
Details from circuit diagram OS/0249 as presented in Jim Elyea's portfolio of schematics.
Serial number 1043
Sold recently (May 2022) in the UK.
Serial number 1064
Serial number 1094
AC30 Top Boost Reverb. The printed circuit board part no. is "PCB 70-1". One of the original Celestion T2056 alnico speakers remains, date code "JE28" = September 1972.
Serial number 1097
Serial number 1101
One of the original Celestion alnico T2056s remains. The other speaker, a Celestion greenback without its back, is a replacement.
Serial number 1126
Superb condition. The speakers are later additions.
Serial number 1151
Superb condition. The speakers are Celestion alnico T1088s, date code "JE25" = 25th September 1972. Note that serial numbers 1094 (above) and 1161 (below) have Celestion T2056s with date codes for 28th September '72.
Serial number 1161
Speakers are Celestion alnico T2056s, with date codes "JE28" = 28th September 1972. See also serial number 1094 further up the page.
Serial number 1172
Serial number 1210
Currently in the UK. Goodmans red-label ceramic drivers, probably original to the amp.
Serial number 1237
Near the end of production. Fitted with Celestion greenback T1234 speakers.
Serial number 1272
Thanks to Tom for the pics.
Serial number 1285
Vox AC30 Top Boost Reverb serial number 1285. ..
Serial number 1300 - currently in the UK
Thanks to Andrew for the picture.