31st December

Even during its greatest period of expansion, JMI did not entirely lose sight of the accordion market. Below, two adverts aimed squarely at accordionists, the first from July 1961, the second from November 1964 (and the latest known promotional instance of the single speaker AC15 encountered so far).

The unspoken rule among players in the 1950s and 1960s seems to have been that 10-15 watts was ample, anything more verging on the undignified. The AC50 certainly will have been regarded as being beyond the pale.

July 1961. In June 1961 the output of the split-front single speaker AC15 was said to be 15/17 watts. Price: 70 guineas (£73 and 10 shillings).

November 1964. For "channels" read "inputs". Price: £84, or £8 and 8 shillings deposit, and 18 monthly payments of £4 and 17 shillings.

30th December

For sale in October 1973, an AC15 noted as being "very old", so presumably with a TV Front. In 1973 it will of course only have been 16 years old at most - a mere stripling - but the TV Front era must have seemed even then like the long distant past.

29th December

A couple of adverts for Goodmans, the first from a Hi-Fi magazine, November 1963 - a fan-framed model, similar to those used in certain AC15 Twins, full price evidently £8 and 8s (8 guineas). A Goodmans Audiom 61 at this time was a little over £13.

November 1963. This at present is the only early promotional picture of a fan-framed Goodmans to have come to light.

The second, from April 1963, embodies a vignette of a group with a TV Front AC15. The organ lower left is not a Jennings though. As the 1960s went on, Goodmans increasingly referenced "popular" music in its catalogues and adverts.

April 1963.

April 1963.

23rd December

The Vox Piano Bass and Pedal Bass, illustrated in the "Vox Precision in Sound" newspaper-format catalogue of September 1964 and produced and sold in relatively small numbers. In terms of electronics, the former was evidently a sort of compact off-shoot of the Continental.

Len Stiles, who regularly had interesting Vox equipment for sale, advertised a Piano Bass in August 1968 - perhaps unsold stock cleared out from the West Street Works by the newly-formed "Vox Sound Equipment Limited".

The standard JMI list price for the Piano Bass at the end of 1965 was £99 15s, so 19gns (£19 19s) - "new" - was quite a bargain.

"Melody Maker", 17th August, 1968.

20th December

Pictures that have come to light recently indicate that the well-known photo of Dick Denney at a Trade Show - below - was not taken at the Russell Hotel Fair of August 1964, but at the exhibition arranged by the "Association of Public Address Engineers" in March 1965. Jennings had been a member of the Association since late 1963 - further details on the Vox AC100 website.

Dick Denney at the Jennings stand, "Association of Public Address Engineers", Harrow, March 1965. A cropped version of this picture was published by Jim Elyea.

At left, in the corridor, one can see "Fi-C". This is Fi-Cord, makers of and agents for high-quality tape recorders. Fi-Cord did not manufacture musical instruments and so did not exhibit at the "British Musical Instrument Industries" shows at the Russell Hotel.

Below, a detail from the schematised floor plan of the stands, Harrow, March 1965. Jennings had 62-65, Fi-Cord were in 60 and 61. Doors/openings are not rendered accurately.

Floor plan of the stands, Harrow, March 1965.

A different shot from the Public Address exhibition of March '65 was printed in "The Vox Story", Denney and Petersen, 1993. The same perspex AC30 and circular plinth were also displayed at the Russell Hotel Fair in August 1964 (present in the pictures recently emerged) and at the Frankfurt Musikmesse in February '65.

A slightly different angle, Harrow, March 1965.

The AC30 centre right in the picture above is probably an Expanded Frequency model (2x15" speakers).

19th December (2)

A couple of quick updates. The date codes of the Celestion T2056s in AC30 serial number 25952, pictured below, are in fact "AF18" = 18th January 1973. Thanks to Dan for the new info.

The second relates to the "BTD Electronics" control unit (entry for 18th December). After further searching it now seems that the closest match for its knobs are those used on amps produced by Tom's new company, "Jennings Electronic Developments" (later "Jennings Electronic Industries"), from 1968 on. So it may be that "BTD Electronics" was an early "Tom after Vox" initiative, a means of making use of (much older) surplus Model H organ power sections.

As Tom had set up his new company at 117-119 Dartford Road, the seller's note still holds good, the only adjustment needed being the substitution of "Jennings" for "Vox".

19th December

Thanks to Dan, pictures of "Vox Sound Limited" AC30 TB serial number 25952, produced in the Birch-Stolec factory in Hastings/St Leonards on Sea, its Celestion T2056s with date code "AF18" = 18th January 1973.

The amp, still in superb condition, was bought secondhand in Hastings in 1974/1975. The page on Birch-Stolec made amps can be found here.

"Vox Sound Limited" AC30TB serial number 25952.

18th December

Sold some time ago, a pair of monobloc amplifiers and a control unit (preamp) made by "BTD Electronics". The seller stated:

"BTD Electronics was a short-lived offshoot of VOX. Probably the most famous hifi you've never heard of."

The speakers contain a single Goodmans (Axiom, I think) unit with adjustable treble."

The amps were produced at the Dartford premises and as far as I know only sold locally and in very small numbers."

General shot of the units.

Transformers are Albions - the mains unit "MT275/120" and the output "OA 063/DT".

In terms of parallels, the Albion mains transformers used for certain AC10 Twins have "MT/300/120", and the chokes "10/120"; AC15s and AC30s respectively "OF-031-DT" and "OH 083/DT".

Valves are: a Brimar rectifier (type at present unknown), an EC83 phase splitter, and two EL84s, cathode biased.

In the power sections, two capacitor date codes are visible, both "UG" = July (not August as previously stated) 1963. Resistors are a mixture of Eries and Radiospares.

The preamp / control unit, with its brushed aluminium fascia and knobs of the type used on mid-1960s Vox effects units and guitars, looks slightly later than the blocs.

A provisional attempt at delineating the circuit of the monoblocs indicates that it is similar in many respects to the output section of the 10 watt Jennings "Model H" organ - introduced in 1958 and designed for home use or in small clubs/chapels. It may be that the chassis in the picture above were surplus organ units re-purposed for sale by (or through) "BTD". Precisely what "BTD" stands for is not known at present - someone, Tom, and Dick/Derek?

17th December

The AC15 Super Twin: advertised twice in May 1962 (on the 12th and 25th), but otherwise unknown, at least in terms of surviving amplifiers. Perhaps a few only were made, sold to those who enquired at Dartford Road or in the Jennings shop on Charing Cross Road in the days or weeks after the adverts had been placed.

If Tom did ask for an AC15 Super Twin to be taken the "British Musical Instrument Industries" Fair in August 1962, there is no sign of it in the picture published in the music trade press of the massed ranks of JMI amplifiers on show.

12th May, 1962: "VOX 15 Watt, Super Twin, Vibravox, 106gns.

Slightly unexpectedly, a random search yesterday evening revealed that a "1965" AC15 Super Twin is thought to exist in Italy (in the hands of a collector). The date or rather dating tends to suggest that the amplifier has a grey panel. More to follow.

16th December

Changes to the ac15 line-up: (1) during the course of 1963, the single speaker AC15 Bass dropped out of JMI's pricelists. Its availability was mentioned, however, in the catalogue of 1964. (2) In late 1964, the single-speaker AC15 disappears from view entirely where catalogues and pricelists are concerned. (3) By late 1966, the amplifier was no longer advertised in any form.

Detail from JMI's catalogue for "Musicland", 88 Broadway Bexleyheath, run by Tom's son Paul. The "AC15 Normal" is the single-speaker model, distinct from the "Twin".

Detail from the catalogue printed in February 1964 (though probably not circulated immediately). Bass frequency models available for the single-speaker AC15 and the Twin.

15th December (2)

A small correction to the note on transformers for AC15s 1962-1963 - the code of the Albion mains unit is "OF-031-DT" not "OF-031-DP". This has been corrected on the page.

It is worth noting that Albion's transformers for AC30s were "OH114" (mains) and "OH083" (output) at first, then later, "OH 114/DT" and "OH 083/DT". "DT" presumably stands for "drop through", ie. through chassis.

Whether Albion made a transformer for JMI with code beginning "OG" remains to be seen.

15th December

Leaping ahead a little where the AC15 is concerned, below, copies of the component sheets drawn up by Thomas Organ (the "V-1-5").

By late 1964, the single speaker AC15 had more or less been phased out, at least where official JMI pricelists were concerned. The model exported to the USA was the Twin and probably exclusively with NORMAL voicing. No provision for the Bass variant is made in Thomas documentation.

Neither the AC15 nor AC30 sold particularly well in the USA, and it was not long before Thomas set about producing (with JMI's consent) its own range of amplifiers, smaller valve models first (to replace the AC4, AC10, and AC15), then solid state. English-made amplifiers were gradually evicted from its catalogues.

The last major order placed with JMI by Thomas came in the summer of 1966 and is likely to have consisted largely of spare parts - cabinets, components, fittings and so on. These were held in stock in the Thomas Service Centers through to 1969 and beyond.

14th December

Thanks to Paul, pictures of serial number 7403N, purchased second-hand in the early 1970s for the astronomical sum of £60. Further shots can be found here.

13th December

The small section on AC15 Twin speakers in 1962 and 1963 on the new page has been tidied up a little. Just to re-iterate, two types of Goodmans speaker were commonly fitted: one with six spokes on its frame, the other with a fan frame. Neither is part of the Goodmans "Economax" range (as has sometimes been suggested). Economax speakers, designed primarily for hifi applications, had two cones, the smaller secondary one serving as a "tweeter".

Nor do the drivers used in AC15 Twins have "Economax frames". If anything, the speaker with six spokes has a species of "241" frame, possibly a "211". Goodmans had various numerical distinctions for type and weight.

It is evident from the pictures below that the Goodmans six-spoke speaker had an impedance of 8 ohms, two wired in series for a total of 15. The fan-framed speaker on the other hand was 15 ohms, two wired in parallel for a total of 8.

The cone code of the six-spoke speaker is "12781", the "12" designating diameter.

Goodmans six-spoke drivers in an AC15 Twin, two wired in series for a total of 15 ohms. The speaker's type, following the standard Goodmans system - frame weight/cone type/impedance - would be something like: 211/12781/8.

An AC15 Twin cab without chassis and back boards. The Goodmans fan-frame speakers, 15 ohms apiece, are wired in parallel for a total of 8 ohms.

12th December (2)

A detail of a single speaker AC15 on stage at the NME Poll Winners concert, April 1962.

A page on the AC15 in 1962 and 1963 has now been started, serial numbers in the 4500s through to the 5000s, chassis made by Westrex, all with copper panels. Further material (ready and waiting) will be worked in over the coming weeks and signalled here on the updates page.

If you see any errors (of omission or commission) do let me know.

12th December

Below, old pictures of two Goodmans Audiom 70 speakers (12" bass drivers, 20 watts handling, 15 ohms) removed from a Jennings Organ, most likely a species of D1 or D2 "Entertainment" organ. The pictures are just a little too old and small to make out any date code.

It is likely that such speakers were also used in "Tone Cabinets" - Derek and Tom's term for extension speaker cabs for organs.

Note the runs of twisted green and yellow wire, typical Jennings procedure.

Technical specifications from the Goodmans "Loudspeaker Manual" of 1960/1961 - 18lbs (8kg) apiece, so not insubstantial.

Price in 1961

Box label from an Audiom 70, noted as being part number 84011.

10th December

A preliminary note on Gla-Rev's contract work for JMI, 1964-1967. Below, AC30 Twin serial number 12784. Typical of Gla-Rev's AC30 cabinets in 1964: chipboard baffles, and a single strengthening cleat for bottom and sides. For the most part the cleats are relatively long, occasionally however no more than 3-4 inches.

Serial number 12784T, thick dark grey vinyl (often used instead of basketweave into the 13000s). The corner protectors are later replacements.

Note the long single cleat strengthening bottom and side.

Gla-Rev's contract work for JMI, 1964-1967

The list below is not intended to be exhaustive. Details on smaller amps will be added in due course. Gla-Rev mainly produced amplifier and speaker cabinets for JMI.

The "G-R" stencil - mostly white, sometimes blue - occurs most frequently in AC100, AC50, and 4 and 7-series cabinets. So far no example has turned up in an AC30. The presence of a chipboard baffle is taken to be a firm indicator of manufacture by Gla-Rev however.

1964: AC30 Expanded Frequency cabinets.

1964: batches of AC30 Twin cabinets with chipboard baffles in the serial number range high 9000s into the 14000s . It may be that the company continued to make AC30 cabinets in 1965 and 1966, but constructed entirely of birch ply.

1964: small batches of AC30 Super Twin speaker cabinets with chipboard baffles.

1964-1966 (?): batches of Foundation Bass speaker cabinets. From Spring 1964, back panels regularly made of chipboard through to around 1966. Chipboard baffles occur too though less often. "G-R" stencils have come to light in two cabs so far.

1964-1966 (?): batches of T60 and 2x15" cabinets. Some chipboard back panels. An unknown number of cabs with chipboard baffles too. No "G-R" stencils so far.

1965: considerable numbers of (if not all) AC50 Super Twin speaker cabinets and amplifier section cases. Chipboard baffles for the speaker cabinets. In 1966 birch ply returns. So far, no AC50 from 1966 or later has been spotted with a "G-R" stencil.

1965-1967: AC100 amplifier sections and speaker cabinets. Chipboard used for some amplifier section baffles by late 1965; for speaker cabinet back-boards certainly by mid 1966.

1966: cabinets for the 4 and 7-series amplifiers. Constructed entirely of birch ply. A good spread of instances of the "G-R" stencil.

9th December

Two types of AC30 Twin cabinet, 1963. The first is what might be called "standard construction", finger-jointed sides, top, and bottom; pairs of triangular cleats inside. The second type has rabbet joints (slab and lip), glued and nailed, cleats also inside.

A detail of finger-jointing on an AC30 Twin cabinet.

The cabinet of serial number 6562. Full birch ply construction, pairs of triangular cleats strengthening sides, top, and bottom. The finger-jointing is visible in other pictures beneath the vinyl covering.

Cabinets of the "standard" type - also Super Twin amplifier section and speaker cabs - are likely to have been made by P.A. Glock (Crayford) and Gla-Rev (Dagenham and Hainault). The note on the characteristics of Glock cabinets by Jim Elyea - p. 137 of his book - really only holds good (with qualifications) for the late 1950s and early 1960s.

The second type of cabinet is less carefully (and expensively) made:

Lower corner of the cabinet of serial number 7521.

Cabinet of serial number 8267. Full birch ply construction, but rabbet-jointed sides.

It is likely that cabs of this second type were produced by Hazell Limited in its Eltham Works. The hope may have been that the vinyl covering would give the cabinet further strength.

Rodney Angell, who worked for JMI as an amp tester in 1963, had a less than rosy opinion of Hazell's workmanship. The company's contract was not renewed.

A third type of cabinet (with particularly intricate finger-joints) was also made for JMI at around this time - c. 1963/1964 - by a contractor at present unknown, pictures posted on the old Plexi Palace Vox forum many years ago. If further info surfaces....

8th December (2)

A quick correction to the entry below: Heslop formally became part of the Royston Group on 1st July 1958.

8th December

Heslop and Company Limited, cabinet makers:

In July 1958, Heslop and Company Limited became a member of the Royston Group of Companies. Its business at the time was listed as "Contract Drawing Office". Royston, true to form, pressed the company to diversify and collaborate with other members of its group - and so during the course of 1965 Heslop took over "Timber Techniques Limited" (Rayleigh, Essex), one of the cabinet makers employed by JMI.

Below, a detail from Royston's annual report (year ending March 1966):

Detail from the Royston Industries Annual Report (1966).

Burndept, also a member of the Royston Group, made numerous types of amplifier chassis for JMI.

Below, a couple of pictures from Royston's in-house journal "The Beacon" of August 1966 - a Continental case being covered at the Heslop Works in Rayleigh, and aspects of a Vox Echo unit being demonstrated.

Thanks to Martin for the two pics.

In addition to cases for Continentals and effects units, Heslop made guitar bodies and necks for JMI; cabinets for the solid state range of amplifiers and speaker units (from late 1966 to early 1968); runs of Line Source public address columns; and - probably - cabinets for AC30s and smaller amplifiers too. More on Timber Techniques, Heslop, and AC30s in due course.

The standard Heslop label, this inside a Line Source 40 column speaker from 1965/1966.

"Gla-Rev", as far as 1966 and later is concerned, produced cabinets for the 7-series and continued with the AC50, AC100, and so on. Whether AC30 Twin cabinets remained part of the company's contract at this time is unknown. No "G-R" stencil has come to light so far.

One point to correct: certain late Super Twin speaker cabinets, it turns out, do have chipboard baffles - very likely a sign of manufacture by "Gla-Rev".

7th December (2)

A note in passing. Some - perhaps the majority - of Celestion T1088s fitted to AC30s by Rose Morris in the late 1970s evidently had RIC cones. Below, one of a pair of speakers with date code "GL29" = 29 August, 1978, cone code "RIC 1 JY".

7th December

Thanks to Walter, pictures of Italian-made AC30 serial number 5913, late 1970 / early 1971, have now been added.

6th December

AC30 Twin cabinets with chipboard (particle board) baffles. These apparently come in around the high 9000s (in terms of serial numbers) - 9986, 9917, and so on into the 14000s. Birch plywood was the norm up to this point. The use of chipboard is normally indicative of manufacture by "Gla-Rev" ("Gla-Rev Products Limited"). AC50 and AC100 cabinets part-constructed of chipboard sometimes have "G-R" stencilled in white. Material relating to AC50 Super Twin cabinets has been gathered on the updates page of the AC50 website. The use of chipboard instead of ply is likely to have been a cost-saving measure.

A number of AC30 Twin back panels may have been made of chipboard too - their inner faces covered with vinyl to give additional strength.

Just to note that in company with AC50 speaker cabinets, baffles of AC30 Expanded Frequency cabinets were also made of chipboard. Although the two types of cab were the same size, they were fitted out with speakers differently however.

A second manufacturer evidently worked in parallel with "Gla-Rev" making AC30 Twin cabinets during this period (serial number range high 9000s into the 14000s). Its cabs were made wholly of plywood. AC30 Super Twin cabinets seem to have been entirely of ply too [ th December: this needs modifying - a few here and there do have chipboard baffles, doubtless a sign of manufacture by "Gla-Rev"].

Further details of cabinet construction to follow.

4th December (2)

The overview of RIC cone codes on Celestion speakers used by VOX, 1960-1963, has now been moved from the entry below, 2nd December (2), to a page of its own. Updates to the table will still be signalled here (on the updates page).

4th December

In 1964, JMI evidently kitted out a small (or at least relatively small) number of AC15 Twins with Fane 12" speakers - probably 122/17s, 15 ohm impedance each, around 25 watts handling (see the detail from the Fane brochure below). They were given heavy-duty labels, as used on the 15" drivers fitted to AC30 Expanded Frequency cabinets (among others).

Quite why Fanes were used instead of Goodmans or Celestion is not known. It may simply have been a matter of available stock. In late 1964 / early 1965, substantial orders were placed however - principally for the revamped large-box AC50 Super Twin speaker cabinets (produced for export to the USA).

Pairs of Fanes were wired in parallel for a total impedance of 8 ohms. Celestion blues, in contrast, 8 rather than 15 ohms apiece, were wired in series for a total of 15/16ohms.

Brown grille cloth, copper panel. Spring 1964.

Black grille cloth, copper panel. Late 1964.

An AC30 assembled from parts by Alan Pyne in the 1970s.

A loose pair from a few years ago.

"122" drivers in the Fane catalogue of 1965. JMI used 122/10s for early Line Source 60 public address cabinets.

3rd December (2)

In progress, a page on later AC15s, 1962 to 1968, serial numbers in the 4500s through to the new sequence for Twins (beginning at 1000).

Below, serial number 4985N, a relatively early Twin, one of at least three produced in blue and oatmeal by JMI in late 1962. In November 1964, Pan Music, which seems to have struck a deal with JMI to sell surplus stock, advertised a blue AC15 Twin ("as brand new") - possibly one of the promotional amps in view.

AC15 Twin serial number 4985N.

A detail from a shot of Adam Faith on stage, NME Poll Winners Concert, 21st April 1963. Photo by Harry Hammond.

November 1964.

2nd December (2)

The overview of RIC cone codes on Celestion speakers used by VOX, 1960-1963, has now been given a page of its own.

2nd December

Below, a couple of Celestion blues, date codes "04GH" and "05GH" = 4th and 5th of July, 1963. One has an H1777 cone, the other RIC 1 KI. In relation to the latter, "04HG" and "05HG" would perhaps make more sense (4th and 5th August, 1962) - and Celestion did put its date code letters in the wrong order every so often - but in this case the question has to remain open.

Further material on Celestion blues coming shortly.

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