Vox AC30 website updates
2021
27th January (2)
Waycom Limited is also likely to have been the source from which JMI acquired its WIMA Tropydur capacitors - "200,000 to 300,000 pieces always in London....".
"Wireless World", July 1960.
27th January
A few more notes on WIMA capacitors. First, an advert from "Wireless World", July 1961 - Tropydurs, the black ovoid WIMA caps used by Vox in 1960 and for a large part of 1961, offered by Smiths of Edgware Road in London. Prices are necessarily retail. Manufacturers would buy wholesale - i.e. with a discount (sometimes substantial) for bulk. Even so, values above 0.1uf will not have been inexpensive.
"Wireless World", July 1961.
In late 1960, English papers began advertising the new WIMA Tropyfols - polyester foil dielectric sealed in resin, gold-coloured bodies, black or red print. JMI began using these in late 1961 / early 1962, presumably bought from Waycom Ltd in London.
"Wireless World", December 1960.
"Wireless World", January 1961.
The front page of a WIMA brochure for the new Tropyfols, April 1960. Thanks to Marc for the copy.
In mid 1962, JMI began using larger WIMA Durolits - 0.15uf, 630v - as the main coupling caps between preamp and power section - C6 and C9 on OS/065, the circuit diagram for the AC30 "Normal" voicing. In 1960 and early 1961 - that is to say in the days when WIMA Tropydurs were used - these capacitors had been 0.01uf, 500v.
AC30/6 circuit diagram, OS/065 - coupling capacitors.
23rd January (2)
Currently for sale in Italy, AC30 serial number 22847, the highest JMI number known. The control panel is JMI too. As in the case of late JMI AC50s, the logo is of the type used for the solid state range from early 1967.
It well may be however that this amp was one of those that remained unsold when the company ceased trading, passing to "Vox Sound Equipment Limited" to be sold in the last third of 1968.
23rd January
Black-print WIMA capacitors. In AC30s produced in late 1961 and 1962, codes can regularly be seen on 400v WIMAs. Those observed so far are "P4", "Q1, "Q2" and "Q3". "P" and "Q" would seem to be the year, the number standing for the quarter. By 1968, WIMA had gone over to the Mullard system for small-value caps, "C8" standing, for instance, for third quarter of 1968.
It is tempting to take "P" as 1961, and "Q" as 1962. Red-print WIMA Tropyfoil (Tropyfol) have a different set of codes, so too the earlier black Tropydurs.
22nd January
Leaping ahead slightly, some preliminary notes on AC30s and the new companies 1968-1973.
Spring of 1968: JMI finally ceased trading, having been in the hands of the official receiver since December 1967.
Summer of '68: Cyril Windiate, who had taken over the running of JMI following Tom's dismissal in late 1967, Reg Clark, the General Sales Manager, and other former members of JMI staff worked together to recast the company as "Vox Sound Equipment Limited" - to produce and sell Vox equipment. VSEL bought in a good amount of unsold JMI stock (auctioned at the West Street Works in September 1968).
Mid 1968 - late 1969: Although VSEL principally sold solid state amplifiers, the AC30 and AC50 remained on the books, appearing in most of its catalogues and pricelists (a good many printed for European markets). Very few AC30s survive however with "Vox Sound Equipment Limited" serial number plates - for which there are good reasons, to be taken up later. The majority of solid state amps sold by the company had clear VSEL badging - control panels, serial number plates, supplied documentation, and so on.
Detail of a "Vox Sound Equipment Limited" brochure printed for the German market in Spring 1969. Note the new American style logo on the AC30 (also used on the JMI and VSEL solid state amps), and the single row of vents on top of the cabinet.
Early 1970 - 1973: "Vox Sound Equipment Limited" crashed in late 1969, having run into severe financial difficulties during the year. Reg Clark, who had taken a new position with Dallas Musical Limited (part of the John E. Dallas Group, not yet Dallas-CBS/Arbiter), tried to interest Dallas in taking Vox on, but talks came to nothing unfortunately. Some weeks later though in early 1970, Vox was re-formed as "Vox Sound Limited", thanks to the efforts of Michael Birch of Birch Electronics and George Stow of the Stow Group. The two later amalgamated their interests as the Birch-Stolec Group. George Stow became managing director of Vox. The AC30 remained in production.
VSL AC30s: Sometimes a peculiar breed. "Vox Sound Equipment Limited" speaker labels were regularly applied to new speakers - that is to say to speakers made by Celestion long after VSEL had folded. Old JMI transformers were fitted instead of the new ones supplied by "Twickenham Transformers" / "Lemark Electronics" (the old and new names of the transformer manufacturer overseen by George Stow's business Group since 1967). Dates were stamped on the new-style tag boards introduced in 1971 at the Birch-Stolec factory in Hastings - "VSL" moved production there in the summer of '71.
A detail of the preamp of AC30 serial number 25628, "Vox Sound Limited" on the serial number plate. The Mullard mustard caps have date codes "C9", "D9" and "B0" - third and last quarters of 1969, and second quarter of 1970.
Serial number 25628 again. JMI Haddon output transformer. The mains transformer and choke are old JMI Albions.
A detail of the preamp of serial number 30865, no company given on the plate, simply "Vox Amplifier" at the head. The board is stamped "6 72" = June 1972. The earliest stamp known at present on one of these new-style boards is "7 71" = July 1971.
The "Vox Sound Limited" inspection tag on an early 1970s AC30. Note the address "Hastings, Sussex" - ie. the Birch-Stolec factory. The three ink stamps suggest that the amp was sold c. 1973 or 1974 - "DMI" must mean "Dallas Musical Industries".
21st January
Below, pictures of a Radiospares 10H choke from the early 1960s alongside the type of choke used with increasingly regularity in AC30s assembled in 1965 and early 1966. Some good examples here - serial numbers 20269, 20523 and so on. The part number of this later type is 66429.
66429s were also used in the summer of 1965 for a run of new fixed bias AC100s built to the "100W Amplifier" circuit diagram - see the examples on this page. The one illustrated below is actually from one of these AC100s. No maker's mark is ever given; but there are often three-letter date codes stamped in white.
Although the frames (housings) are different, the formers are identical: five slots on one side, plain on the other but with a sort of tongue on top. It may be that the later chokes were also supplied by Radiospares.
Radiospares, however, was generally not a manufacturer - simply a commissioner of items made by others and branded with the Radiospares name. The principal manufacturer of the transformers supplied by the company is reckoned to be R.F.Gilson of Wimbledon (South London). But whether Gilson produced these chokes is unknown.
20th January (3)
Details of two of The Beatles' AC30s - John's and Paul's - October 1963. Both Beatles are plugged into the Brilliant Channel. John's volume is set at just short of 12 o'clock; Tone either at full on or full cut - probably the former. Paul's volume is at around 2 o'clock, Tone at full cut. Further pictures to follow.
20th January (2)
Super Twin amplifier section serial number 5156N (probably late 1961 / early 1962) has just come to light. Thanks to David for the picture and info.
20th January
Some pictures on this page of an untouched Westrex-made grey panel chassis from the third quarter of 1964. Latest visible dated components: the original ECC83s, May '64. It was in full working order (no attention required) in 2015.
19th January
Serial number 22117, produced in 1967 (probably the second half), owned by Dave Davies of the Kinks, sold on ebay in May 2007.
A screengrab from the ebay auction page.
18th January
A note on chokes in early AC30s (1960 and 1961). The earliest were standard Radiospares catalogue items. They accompanied Haddon mains and output transformers in AC30/4s and pre- and some post-LOC AC30/6s. In late 1961 Haddon produced its own choke, as did Albion (and Woden later on - late summer of 1962).
The AC30/4 and AC30/6 circuit diagrams both give the value as 10-20HY and 100MA. "HY" stands for "Henrys", the measure of inductance.
Detail from OS/065, the AC30/6 Normal voicing.
The outward facing side of the choke on an AC30/6 pre-LOC chassis.
The chassis side of the choke on another chassis, original label present: 20 Henrys, 500 ohms (DC resistance), 100 Ma.
The reason why the circuit diagram gives 10-20HY inductance becomes clear when one refers to the Radiospares catalogue of 1961: the two values were available in housings of the same size and format. If one was out of stock, the other could be used. As far as the schematic was concerned, JMI evidently thought it well to reference both (just in case), leaving the sheets uncorrected as copies were made. By the end of 1962 chokes were 19H.
Detail from the 1961 Radiospares catalogue.
1961 Radiospares catalogue cover.
Although no definitive example of a 10H choke has come to light so far in an early AC30, many are "unknowns" - only the outward facing side of the housing normally being recorded in pictures. Labels on the "inner" side are often discoloured or absent.
17th January
A new page on documents 1966 has been started. A page on the final AC30 Twins produced by JMI - serial numbers in the 22000s (1967 and early 1968) - will be posted soon.
16th January
An advert placed by Gamlins of Cardiff in the "Merthyr Express", early 1963. The list of amps (and prices) is similar to the one given in the JMI promotion for the new AC10 Super Reverb in "Melody Maker" magazine, February 1963 - see this page.
The T60 is at this point called the A.C.60 Transonic Bass. Two 2x15" speaker cabinets are recommended. Price: 145 guineas. The A.C.30 Super Transonic - a solid state T60 amplifier unit in a futuristic case (see the entry for 23rd December, below) - is 150 guineas.
15th January (2)
A page on AC30s with serial numbers in the range 20000-21000 - late 1965 through to 1967 - has now been started here.
15th January
Just to signal that the page on Burndept, Vox, and the West Street Works on the AC100 website has recently been updated (further updates there to come). A page of a slightly different nature will be set up here, referenced more specifically to AC30s. For the moment, details from two Ordnance Survey maps to show the position of the Works in Erith, and the address panel from a Burndept flyer of late 1964.
Although Burndept's principal business was telecommunications equipment, particularly for the aviation industry, the company manufactured a wide range of things - scientific instruments, domestic electronic goods, even at one time cookers. Contract work had been undertaken from the 1950s. By 1961 a controlling interest in Burndept had been taken by Royston Group of Companies; Vox was added to Royston's portfolio a year or so later - late 1962 / early 1963.
With the opening up of the American market in 1964, Vox had to expand. Burndept made space in its West Street Works (top floor and some rooms on the first), and over the course of around six months a wide range of activities were moved there from Dartford Road. Royston reported at its Annual General Meeting in July 1965 that the move was complete. One of the consequences of these changes was that the contract with Westrex was not renewed. The Burndept / Vox Works could provide the majority of amplifier chassis. Triumph Electronics, which had been brought in as a contractor in late 1963, retained a fairly limited brief (being a relatively small concern), however: AC50s, PA amplifers, and occasional runs of other things, notably in 1966 the 4-series and 7-series range.
Above, details from two Ordnance Survey maps of Erith.
Burndept flyer of late 1964. The telephone number of the West Street Works - ERITH 33080 (which became the Vox telephone number) - is crossed out and a new one typed on. Burndept retained most of the ground and some of the first floor of the building for its own operations, making over the second (top floor) entirely to JMI.
14th January (2)
A detail of a picture taken in 1967 in the Vox Works, Erith. The AC30 in view is a Top Boost model with large main coupling caps (Dubilier) and an array of smaller dark- and light-coloured signal caps. The dark ones are presumably red Lemcos, the lighter ones Dubiliers, as used in the fully solid state amps and late-run AC50s produced by JMI.
On the centre handle an inspection tag, and in the bottom of the box the guarantee documents in a brown envelope.
In 1967, wooden cases for the solid state range were supplied in "undressed" form by the cabinet makers Heslop and Gla-Rev - in other words, no vinyl, no grille cloth, no holes for handles, and so on, just the plain case. Covering and fitting out was done by JMI staff at the Erith Works. This is likely also to have been the case for AC30s.
Serial number 22177.
13th January (2)
One of the fonts used for copper panels in 1963 (letters and numbers) is "Futura Bold", as supplied at least by Letraset (which came into being in late 1959). The company's dry transfers will have been used for much design and layout work. As well as producing letters and numbers, Letraset also supplied lines, circles, and so on - graphics of all sorts for layouts.
Below, specimens of "Futura Bold" from the catalogue of 1966. The font was part of the range introduced in 1961:
Catalogue, 1966.
Letraset advert, 1961
13th January
AC30 serial number 17758 from the last quarter of 1964. The original EL84s that came with the amp have date code "B3J1" = 1st week of October 1963; two of the ECC83s, date code "B3E1" = 1st week of May 1963; and the GZ34 rectifier valve, "B2K3" = 3rd week of November 1962. Thanks to Rolf for pictures and info.
The voltage selector is of a type used for only a short time, also on certain AC10s and AC50s - new-style dome case, but a slot on top (presumably so a penny could be used to help turn it).
11th January
Some notes on the "etch and fill" process used to create JMI grey panels in the period 1964-1968, and around 100 black panels for AC80/100s in late 1964 and early 1965.
In very broad outline: - (1) an even layer of brass was applied to the surface of the aluminium; (2) legends and lines were screened on in an ink resistant to acid; (3) acid was applied to the top of the plate - this etched into unprotected areas of the brass, leaving legends and lines standing proud; (4) legends and lines were coloured in silver; (5) blue / grey enamel (black acrylic in the case of AC80/100 panels) was run into the sunken areas of the brass.
Aspects of the process can be seen best perhaps in AC50 panels. For some reason the silver colour applied to the legends of these panels was not all that resilient. Below, an example (one of a number) from which almost all the silver has gone, leaving the raised brass legends and designs.
Panel from an AC50 with a serial number in the 3000s. All silver has worn away, exposing the underlying brass. The brass is also revealed by the scratches in and wear on the coloured infill. Legends and lines stand slightly proud of the colour.
A detail of the black panel of AC80/100 serial number 241. Note how the silver has clogged some of the bowls and openings in the letter forms.
As mentioned at the foot of this page, JMI commissioned "etch and fill" panels, though probably in quite small numbers, as early as mid 1962.
10th January
Recently sold by "Howl Guitars" in Tokyo, an early Super Twin amplifier section, beige cloth, early 1962. The amplifier chassis, made by Westrex, has Haddon transformers, the earliest type of copper panel, white EL84 sockets, and the phantom cut-out for the rectifier valve. The serial number plate, with its three long panels and peculiar attempt at hand stamping, a later addition to this amp.
9th January (2)
The "AC30 Lightweight", not really an AC30 at all, but a solid state T60 amplifier section and supplementary solid state vibrato unit in a 3x10" cabinet. On the plate the model is given as "A.C.30. L". The serial number is part of the sequence of T60 amps.
The AC30 Lightweight ("Transistor Lightweight Thirty") iin the JMI Dealer Catalogue of 1964.
9th January
A page on control panels has been set in motion here. Notes on manufacturing processes will follow soon, probably on a page of their own.
8th January
An AC30 with integrated top boost in its copper panel has an Albion output transformer with a stamped date - 14th October 1963. The amp is currently in Japan and registered at the foot of this page.
Albion transformers tend to have dark-coloured varnished paper coverings over their windings (as above), at least from mid 1962. Haddons generally have relatively loose-woven cloth, lightly varnished. Woden transformers have yellow waxed paper tape.
6th January
Further fairly random notes on panels. These will be gathered together more coherently on a page of their own. Most standard black and gold panels on JMI amps (AC10s, AC15s and AC30s), c. 1960 to 1961, were laid out with the same font. The font was used for copper panels, as mentioned below, through to early 1963, at which point a new style of "typography" was introduced.
Specialist panel makers made the majority of panels for JMI. A few, however, were produced in-house - silk-screened and painted.
Note the flaking of the paint. Thanks to Glen for the picture.
The process of producing anodised panels was a complex one. Effectively the steps were: (1) preparing the artwork; (2) setting it up as a silk screen mask; (3) silk screening the bare aluminium with the design in an "ink" that was resistant to acid; (4) immersion of the panels in the anodising acid bath (electricity applied to the bath); (5) rinsing with water; (6) immersion in the dye colour; (7) boiling in de-ionised water; (8) the cleaning away of any ink that remained over the legends to leave the bare untreated aluminium.
Steps (1), (2) and (3) have several sub-steps. Perhaps the most difficult thing, from the point of view of layout, was the "JMI" logo. Black and gold panels have further steps, a second anodisation process to add gold to the legends and lines.
Grey panels were made by a different process - "etch and fill". Details in the design were fairly consistent from 1964-1967. However, early on there may have been at least one variant:
The panel on an early grey panel AC30T. Notice the smallness of the "JMI" logo on the large plain metal background, and the lack of "MAINS", "WARNING" and "SELECTOR". Possibly a repro? It looks to have been made by an anodising process rather than etch and fill. No other example has yet come to light.
Super Twin serial number 2739, an AC30TB (top boost integrated in panel), mid to late 1964. The standard form of the JMI logo on grey panel amps.
Super Twin serial number 5438, an AC30TB, c. 1967. The "JMI" logo is on three discrete parallelograms. They have no contact with the bounding lines. In effect, a return to the format of the copper panels.
Grey panels invariably have "FUSE" rather than "3 AMP.". Occasionally wear brings the brass sub-layer of the "etch and fill" process to the surface. Thanks to Glen Lambert for all advice on the design and manufacture of anodised panels.
5th January (2)
Details from the shots in the previous entry, approximately to scale. The letters on the black panel are slightly more dispersed:
5th January
For comparison, a detail of a "standard" Pre-LOC AC30/6 black panel (early 1961) against an early copper panel (early 1962). The fonts appear to be the same. Note the flat-headed "3" and the "1" with pronounced downward tick. The "JMI" blocks look to be the same too, though the letters on the copper panel may be slightly elongated. There are differences though in the spacing of the letters in at least one of the legends - "MAINS".
Serial number unknown.
Serial number 5002.
4th January
Picking up from yesterday, a copper panel from an amp not too far removed in terms of date from serial number 6822. The three silver parallelograms on which "JMI" sits are narrower and a little more angular; the gap between the JMI logo and "PRODUCT" has been reduced. Letters and numbers are generally spaced further apart. Evidently a third template (at least) by 1963.
Serial number 6822.
Serial number in the low 7000s (?).
3rd January (2)
A small work in progress on copper panels. In 1963 the design changes. Early on the text of the legends is relatively fat; "PRODUCT" lies mid-way between the JMI logo and the silver line; "JMI" is in slightly finer letters.
From some point in the 6000s, the legends are given in taller, thinner type; "PRODUCT" lies closer to the silver bounding line; "JMI" is heavier.
Serial number 6038 appears at present to be the earliest AC30 with one of these revised panels.
Serial number 5002.
Serial number 6822.
3rd January
Further pages from the Vox (Rose-Morris) catalogue - the various formats of AC30 (solid state and valve), along with the AC50 and colossally heavy AC120 combo.
Page 3 of the catalogue, continued below (page 4), and detail.
Detail of the schema of the control panels of the valve AC30s.
The "Electronics and Music Maker" magazine review of the Rose-Morris AC30, December 1981, can be found here.
2nd January
The Vox catalogue of 1981, containing pictures of the factory at Shoeburyness (the old Hayter drum factory). At the time Vox was owned by Rose Morris, having been purchased from CBS-Arbiter. On the front cover, a great shot of AC30 chassis at different stages of completeness on racks. "The Vox Story", ed. Denney and Petersen, has further shots of the assembly process.
1st January
A Happy New Year! Just to signal that a page has been started on the early Jennings companies, correcting some of the things that have been ventured in various printed sources and on this updates page. "Jennings Musical Industries Limited" came into being in the summer of 1956. The first ad. for the new company appeared in "Melody Maker" on 23rd June.
"Jennings Musical Instruments Limited", Tom's first company, ran from 1949 to 1968. The two others had shorter spans. "The Jennings Organ Company Limited" came into being around 1952, and "The Jennings Accordion Company Limited" around 1955. Both had disappeared by the time Tom sold a controlling interest in Jennings to The Royston Group of Companies - late 1962, not late 1963 or 1964, as one sometimes reads. The selling of the stock to Royston is recorded (having already taken place) in "The Guardian" newspaper in January 1963.
Further material will be added to the page shortly, a related page on Jennings Organs to follow.
""Melody Maker" magazine, 23rd June, 1956, along with the accordion version, "Accordion Times", July 1956. Note in both instances the signalling of "Trade Mark".
2020
31st December
Back in August (entry for August 12th), I posted some pictures - repeated below - of numbers inscribed on chassis assembled by Westrex for JMI.
A further "165" has just come to light on AC30 serial number 12569 - thanks to Ben for the pic.
AC30 Twin, serial number 12569.
An AC80/100 from the third quarter of 1964 (serial number plate lacking).
AC30 Super Twin, serial number 3021.
AC30 Super Twin, serial number 3863.
The same person inscribed "119" and "130" on other amps. The signifance of these numbers is unclear at present. "119" naturally makes one think of Dartford Road. But "130" and "165"?
30th December
Below, six pictures from a larger set of a late black panel AC30/6. The serial number plate is a reproduction of a later type (with long silver panels), deliberately scratched up to make it seem "old". The number - 5014T - is nonsense. But the chassis is right for later 1961.
Transformers are Haddons. The chassis (assembled by Westrex) has the wrongly-positioned hole for the rectifier valve. Every capacitor in the preamp has been replaced. The cabinet, which is probably original to the chassis, is in excellent condition.
29th December (2)
"Melody Maker" magazine, 20th December, 1952. A fantastic design from "WSE". "WSE" was the company that Jennings recommended for amplification in the early 1950s, stocking certain of its models in the shop on Charing Cross Road. Anything but Selmer.
"Melody Maker", 20th December, 1952.
29th December
Detail from a picture of The Kinks rehearsing for a BBC broadcast at the Playhouse Theatre, London, September 1964, Pete Quaife with a Super Twin amplifier section and T60 bass cabinet.
The Kinks, Playhouse Theatre, September 1964. Getty Images.
The page on later Super Twins (late 1964-1968) has recently been updated. In late 1964 and early 1965, Burndept had evidently either bought in large stocks of components or hugely over-produced. At least two chassis with serial numbers in the 4700s (1966) have components with surprisingly early date codes.
28th December (2)
For many the picture below published in "The Vox Story" (1993) will have been the first encounter with an AC30 in a slope-sided amplifier section cabinet.
The amplifier pictured is a "Super Twin", top boost presumably on the back panel, serial number unknown.
The comment "introduced for the U.S. market" is spot on. Substantial numbers of these new-style amps, "Super Reverb Twins" first, then "Super Twins", were produced for export to the USA from early 1965. Below, one of the first catalogue images of the AC30 SRT in its finalised form.
A detail from the Thomas Organ "Million Dollar Sound" catalogue of late 1964 / early 1965. Although the text describes the "Super Reverb Twin", the runner on the front of the amp says "Super Twin". Note the "basket" on top of the trolley to hold the amp.
A good number also went to Germany. At present, the earliest AC30 SRT to have come to light so far in a new-style slope sided cabinet is serial number 3523. The earliest slope-sided AC30 ST is serial number 3863.
There is, however, in the States a slope-sided AC30 ST (sold on ebay a while ago) apparently with the number 2825, which seems incredibly low (but possible perhaps). Whether everything goes together though is difficult to say. The Celestions seem to have Thomas Organ part number labels on them.
28th December
A new page on Super Reverb Twins, 1965-1968 has now been set up. Some additions to follow.
AC30 SRTs destined for export to the USA were often fitted by JMI with a 0.05uf 500v Radiospares capacitor from the mains switch to ground - a means of suppressing arcing, if there should be any, at switch on. The capacitor does not appear on any circuit diagram. AC50s and AC100s were also fitted with these capacitors (again not represented on any of the sheets that have come to light).
AC30 Super Reverb Twin serial number 5031.
27th December (2)
Jennings advert in "The Organ Quarterly", April 1958, the note at its head indicating that an organ had been installed in the Civic Auditorium, Lower Hutt, New Zealand. The building was constructed in 1957.
Jennings had up to this point mainly exported Univoxes, but not much more, to New Zealand (Upper Hutt and elsewhere) and Australia - see the brief note on this page.
It is interesting to see that the model - Model "G" - installed in the Auditorium was brand new, and not available at the time in the UK.
Civic complex, Lower Hutt, New Zealand.
"The Organ", April 1958. Mr Mackay is now the Sales Manager, replacing Leslie Morley. See below, entry for 16th December.
27th December
Eight more Twins from mid 1964 now added - six Trebles, one Bass, and one Top Boost. Serial numbers 13169T, 13270B, 13492TB and 13707T on this page. Serial numbers 14388T, 14595T, 14934T and 14970T here.
Some more coming shortly on late Super Twins.
26th December
The page on Twins with serial numbers in the 18000s and 19000s is now up. Chassis (mainly "Top Boost" in panel) were made primarily by Burndept - in common with most Twins with numbers in the 11000s or higher. Chassis made Westrex were generally allocated to Super Twins.
In early 1965, the contract with Westrex came to an end however: in late 1964 JMI had moved a large part of its operations into Burndept's West Street Factory in Erith - the "West Street Works". From around the second quarter of 1965, Burndept became the sole manufacturer of AC30 chassis, and the principal manufacturer of AC50s and AC100s, though Triumph Electronics in Purley augmented production of these last from time to time.
23rd December (2)
Slightly better pictures of the first edition of "The Shadows Modern Electric Guitar Tutor", 1963. The second edition followed fairly quickly on its heels with much the same principal content, but different Vox adverts, and an improved picture of the Phantom guitar on the cover.
Second but last page. The last has pics of Vox guitars.
The standard picture of the AC30 in beige with a note to say that the amps used by The Shadow (illustrated in the body of the book) were in black.
Dynamic Vibravox.
23rd December
Pictures of Bill Wyman's AC30, serial number 5048N, bought before he joined the Rolling Stones. Pictures from Julien's Auctions. The catalogue entry - available here - states that the amp was built in February 1962. Although no point of reference is given (speaker date codes perhaps?), this seems right. Serial number 5002N has speakers with date codes of late December 1961, so *final* assembly - i.e. the making ready of number 5002 for sale - is likely to have been in January/February '62.
Serial number 5048N, owned by Bill Wyman from 1962-2020.
21st December (2)
Kenny Lee and the Mark 4 in 1964 with a TV Front AC30, two later beige Twins, and a beige Super Twin. The first two shots were taken during the band's residency at The Big Ben Club, Wilhelmshaven, 9th February to 28th March, 1964. The third comes from a second residency, 4th - 10th May
All three pics from this page.
21st December
A little more on Expanded Frequency AC30s. Serial number plates - at first they are much the same as standard twins with serial numbers in the 10000s but with an "X" stamped after "AC/30".
Serial numbers 10457 and 10471 were stamped in the same way.
Towards the end of 1964, production of AC30X chassis was taken over by Burndept. At this point, a new sequence of serial numbers was brought in, beginning either at 500, or more likely, 550 - remember that the new Super Twin sequence, introduced earlier in the year, kicked off at 2500, not 2000.
Stamping of the plates in the new AC30X sequence was fairly haphazard. There are at least three varieties:
Serial number 584. "EX 30". New style plate with longer silver panels.
Serial number 589. "AC.30 EX". A different set of stamps.
Serial number 593. "AC.30 X 15". All still hand stamped.
A further thing to mention is that the Expanded Frequency cabinets *may* have been made by Gla-Rev. At any rate, all that have come to light so far have chipboard (particle board) baffles rather than solid ply.
Cabinet of serial number 593. Chipboard baffle. The speakers are 15inch Celestion T1109s.
20th December
The first of two sets of notes on copper-panelled chassis with integrated top boost - i.e. separate treble and bass controls, making eight on the panel in total rather than the six of standard Twins - Vibrato Speed; Vib-Trem Switch; Vib-Trem, Normal, and Brilliant channel volumes; Treble; Bass; and Cut.
Most, if not all of the chassis were made by Westrex, presumably to keep complications of production to a mininium. Not only did they have to be specially fabricated; with six valves rather than five in the preamp, they had to be wired differently too.
On the underchassis one often finds, in pencil, an X in a circle = "Expanded". Two examples below, the initials "DP" preceding - see the entry for 14th Dec. lower down this page for further examples of the initials alone.
One has to admire the thoroughness of "DP". That the chassis was an "expanded" one will have been clear at first glance.
A detail of a chassis from an Expanded Frequency AC30 with a copper panel - further pics on this page.
Details above and below of a copper panel chassis with integrated top boost from a standard AC30 Twin (serial number unknown, but probably somewhere in the 10000s).
Why the first example should have an old-value cathode resistor - 82R rather than the 47R/50R introduced in the last quarter of 1963 - is difficult to say. Perhaps a replacement? Its legs are certainly not sleeved (as they often were at factory). A pity that its date code is not visible. The date code of the other amp's cathode resistor (50R - and it is 50 rather than 80) is plain enough though - "UH" = August 1963.
Although underchassis are perhaps the least well represented part of AC30s in terms of photographs, it may be possible gradually to build up a picture of how long the "cross-over" period lasted between old value resistor and new.
19th December
Pictures from some time ago of a Twin of 1963 or 1964. The back boards of the cabinet have rounded corners, so a serial number higher than around 7300-7400 is in view. The presence of a round footswitch would normally suggest *no* higher than the high 7000s, when the new egg-shaped switch comes in. However, the serial number plate, with its long silver panels, must bear a number higher than the mid 11000s.
So footswitch or plate - perhaps even both - cannot be original to the amp. At some point it may be possible to identify or "place" it though. Note the presence of the cover, probably burgundy in colour.
18th December
The Blackhawks at the Gaumont Cinema, Hinckley, c. 1962 / 1963. A great shot of an AC30 Super Twin on stage, the amplifier section with leather rather than black plastic handle. Pic from this page.
17th December (3)
Now added, a chassis from an amp originally with a serial number in 12000s - perhaps number 12253. Thanks to Michael for the pictures.
17th December (2)
The entry for serial number 11873 has been updated. Thanks to John for further pictures and info.
17th December
"Melody Maker" magazine, 10th August, 1957. This *at present* is the earliest public mention that has come to light of the new company "Jennings Musical Industries Limited". See the entry below (1st December) for the others - "Jennings Musical Instruments Limited" (from 1949) "The Jennings Accordion Company" (from 1949), and "The Jennings Organ Company" (from at least 1954).
It is very tempting to race ahead and say that part of the reason for bringing "Jennings Musical Industries" into being lay in the decision to produce ranges of guitar (and accordion) amplifiers - for which Dick Denney had been hired. That the ad below gives no such hint may simply be due to the fact that the amplifiers were not at the time advanced enough to advertise. Guitars (produced by other manufacturers) had been part of the Jennings catalogue from late 1950.
"Melody Maker" magazine, 10th August, 1957.
16th December (3)
Preliminary pictures of the first edition of "The Shadows Modern Electric Guitar Tutor", 1963. Further photos to follow. The Jennings advert for AC30s in the second edition can be found on this page.
The Transonic (four control version rather than three); a beige AC30; and a Super Twin in black.
At the foot of the advert: "All VOX amplifiers feature the dynamic Vibravox. This is a unique method of introducing both frequency and Amplitude control, it is this combined effect which gives VOX amplifiers their characteristic Vibrato.
16th December (2)
"The Organ Quarterly", July 1957 - a letter to the editor from Leslie Morley, Sales Manager at Jennings in the mid to late 1950s (i.e. one of Reg Clark's predecessors). The article to which Morley was responding will be posted in due course. It was clearly stinging, but not without merit.
Have a look at the advert below (entry for 7th December) - a Jennings organ with what looks to be the interior of Ripon Cathedral in the background. Not really a practical proposition. By 1961, Jennings and Selmer had ceased advertising in the periodical, the ads for that year being from makers whose organs really could fill Ripon with sound.
16th December
Pictures of serial number 5503N, which is likely to have been ready for sale in the autumn of 1962, added on this page - external views only.
A combined page on AC30s with numbers in the 18000s and 19000s coming soon, along with some additions to the existing 13000s and 14000s.
15th December (2)
Difficult to know what to do with this one. Sold at Heritage Auctions in 2020. Serial number 8356B. A nice-looking Twin on the face of things. But the copper panelled chassis has integral Top Boost, which first occurs in AC30s with serial numbers in the 10000s. Perhaps there is some good genuine example in the high 9000s - but the 10000s are the real locus for these new panels.
The cabinet (which has back boards with rounded corners) is in excellent order - which is always good to see. And it still has un-radiused corners - i.e. a flat profile front and back. Radiused corners appear in the 12000s.
15th December
A couple more Twins with serial numbers in the 6000s registered towards the end ot this page: number 6898B (though the wooden cabinet is evidently from a later amp), and 6948N.
14th December (2)
Serial number 5916N added on this page, along with some new pictures of 5937N. Both are likely to have been made ready for sale in early 1963.
The underchassis of 5937N is marked "DP 52" in pencil. It is not clear at present what the initials signify - perhaps they are of the person who checked the amp? "DP" is also found on a chassis (now parted from its cabinet) produced a few months later.
Detail of serial number 5937N.
A stray chassis from mid 1963.
14th December
Three more AC30s from the first half of 1964 added: serial numbers 11308B; 12450TB; and 12787B.
13th December
The page on "documents", 1959, has now been started - available here. A representative selection of material on organs will be incorporated soon. Organs, along with accordions, were an important part of the business in 1959.
The prices of the four principal models of amplifier advertised - the AC10 with and without vibrato, AC1/15 (renamed the AC15 from September 1959), and the AC/30 - remained steady throughout the second half of the year.
"Melody Maker" magazine, 26th September 1959.
12th December
A "documents" page coming soon for 1959 - the principal amplifiers in the Jennings catalogue being the AC10 with and without vibrato; the AC15; and the new single speaker AC/30 (from the summer of 1959).
Below, notice of a venture that seems not to have taken off: the Jennings "British Organ Hire Service".
"Melody Maker" magazine, 7th March, 1959.
10th December
A Jennings advert in "The Stage", 5th of May, 1955, to coincide with the "British Industries Fair" (B.I.F.). See the ad in "Accordion Times" at the top of this page. The Jennings demonstrator, Eric Easton, went on to manage the Rolling Stones. His link with JMI may have been useful, though it is unlikely to have been paramount in his appointment.
Once the various legal cases following his dismissal in 1965 had been settled, Easton moved to Florida, and set up in business selling organs.
"The Stage", 5th May, 1955.
9th December (2)
An interesting AC30 in the States. The chassis is from 1964 - Woden transformers with date codes "KU" and "MU". It will originally have belonged to a box with a serial number in the high 9000s or low 10000s.
The present box is much older however. Note the square corners of the back boards. But it has been revamped: new vinyl covering, grille cloth, and corner protectors added at front (with double pins). The serial number plate is typical of those used for a short time on black panel amps of early summer 1961 - serial numbers in the 4600s - 4680 for instance. The speakers in the cabinet may date from this time too.
So an instance of a later chassis being slipped by a restorer into an early box rather than the other way round (see below, first entry for 8th December).
9th December
In 1965 and 1966, JMI retail pricelists meant very little in cities. Dealers and larger shops bought from JMI at a discount and sold at well under the list price. £70-80 was around the average one paid for an AC30 in London in '66. Below, adverts from "Melody Maker", 5th March and 3rd September. Pan Music was a major seller of Vox equipment from early summer 1965; Rudall and Carte (formerly Rudall, Carte and Rucke) dealt mainly in instruments for the orchestra, though the shop normally had selections of guitars and amplifiers too - increasing numbers as the sixties rolled on. In September 1965, Rudall listed a second-hand AC80/100 bass set for sale, probably one of the earliest to have been offered second hand in the West End.
"Melody Maker" magazine, 5th March, 1966.
"Melody Maker" magazine, 3rd September, 1966. Rudall also invited buyers to make offers on items of non-functioning equipment - echo units, guitars, amplifiers, and so on.
8th December (2)
A great picture of Dick Denney at the launch of "The Vox Story"; at left, Alan Hutton, manager of the band "Force Four". The frontispiece is signed by Dick and David Petersen (his co-author); Jack Jennings (brother of Tom, and in charge of Despatch at JMI); and Alan Larkins and John Bethull formerly of JMI Research and Development. Thanks to Bill for the pictures.
8th December
A late black panel AC30/6 chassis - probably late autumn / early winter 1961 - recently sold on ebay. The wooden cabinet, speakers, serial number plate, and so on, were all from later sources, different in each case, a real patchwork amp (probably created in the 1990s). Further pics on this page.
Note the white EL84 sockets, and the closed-up phantom hole for the rectifier valve. Transformers are Haddons. The Woden choke, date code "HT" = August 1962 - is a replacement from yet another amp.
7th December (2)
The serious business of building and selling organs - the advert below placed by Jennings in July 1957 in "The Organ Quarterly", a review aimed at organists and historians of ecclesiastical music and instruments. Remember, Derek Underdown and Dick Denney will have been at work designing the Vibravox and AC2/30 at much the same time as this page appeared.
"The Organ" was published by "Musical Opinion" magazine, in which Jennings also advertised. See below, entry for 1st December.
7th December
Serial number 5672N, bought new in 1962 along with the Strat. The amp is fully original (no electronic or cosmetic repairs/renewals). The stand was purchased later. Thanks to Kevin for the pics of this superb AC30.
4th December
Thanks to Danny, further pictures of serial number 16041 now added here.
Just to note that the cinema amplifier with Woden transformers pictured below (entry for 28th Nov.) is a Bell and Howell design - a species of "Filmosound" amplifier - manufactured under license in the UK by a division of the Rank Organisation.
2nd December
A small quirk of the AC30 chassis made under contract for JMI by Burndept from late autumn 1962 - the small cut-outs in the aluminium preamp upright for the cage nuts. Chassis produced by Westrex do not have these; nor the early chassis made by Burnham Engineering (Dartford).
Details from serial number 6097.
1st December
A few notes about early Jennings days. Up to and for a little way into 1957, there were three companies: "The Jennings Organ Company", "The Jennings Accordion Company", and "Jennings Musical Instruments Limited".
"Jennings Musical Instruments Limited" plaque on the headstock of a guitar sold by the shop on Charing Cross Road, c.1954. The guitar however was not made by Jennings. One also finds these plaques on the accordions that Jennings sold. Badges on early amplifiers tend just to have "Jennings"
By the end of 1957, a fourth company was brought into being: "Jennings Musical Industries Limited". This became the principal name presented to the public. Occasionally in early advertising one finds "Jennings of Dartford", but that was simply useful shorthand, not a company. "Jennings Musical Instruments Limited" survived until late 1968. It is the company cited by the executors of the JMI wind-up sales in September 1968.
As has been mentioned, Jennings-made console organs (ie. organs with wooden cabinet, built-in amplifier and speakers, and "bench" style seat) were important in early days (and indeed remained so until around mid 1965). In the late 1950s, "The Jennings Organ Company" took out a series of ads in "Musical Opinion" magazine, a monthly journal covering a wide range of "high-brow" musical subjects - recent classical concerts, new books and recordings, and articles on the restoration and repair of pipes and keyboards. The Royal Academy of Music and The Guildhall were regular advertisers, along with the long-established makers of keyboard instruments. Below the Jennings ad in the issue for February 1959.
Six models are presented, some not even remotely cheap. The advert placed by Jennings in the issue for May 1959, can be found on the Combo Organ Heaven website. Selmer also placed adverts for its organs in the magazine - in February 1959 a double page spread.
"Musical Opinion" magazine, February 1959, front cover.
Remember that from 1958 Jennings was beginning to sell increasing numbers of AC10s and AC15s. Its two prospective audiences could hardly have been more different: beat and skiffle groups on the one hand; church, church hall, and club/community organists on the other. By early 1960 accordions were on the way out.
A new page on select early Jennings things will be coming soon.
Updates for October and November 2020 are now on this page.