VOX AC100 - UPDATES AND NEW INFO
A note on late AC100s. In late 1967 Royston Industries, parent company of Jennings Musical Industries, went into receivership, propelled into a financial down-spiral by the failure of the Midas Flight recorder, the development of which had drawn significant sums from the working capital of Burndept Electronics, Jennings, and so on. Devices for aviation produced previously by Burndept had proved successful. But not this.
In February 1968, with things worsening, Royston had no option but to liquidate its assets, and at this point plans were formed for the divesting of Jennings/Vox, which was pretty much dead in the water. For some of the documentation, see this page on the Vox Supreme website. Vox rose again in June 1968 as "Vox Sound Equipment Limited" (VSEL).
Production of the AC100 seems to have stopped however in late summer 1967 well before these troubles became fully public and in spite of a circuit revamp in mid 1967 - the new circuit expressed in schematic OS/167, dated 16th July. In practice it is likely to have been adopted a little earlier, however. These sheets, always drawn up neat, were issued for repairmen, not the assembly line. Amps built to that circuit are registered here.
That Triumph Electronics was contracted in '67 to assemble small runs of amps may simply have been expediency - a means of using up components or getting something back for money that had already been paid. The end of production of the AC100 at the Burndept Factory (the "Vox Works") doubtless resulted from a diminishing market interest in the amp and a growing desire to move, with all guns blazing, to solid state.
The AC50, however, for which there was still a market, remained in production through to early 1968 - see the amps on this page. "Vox Sound Equipment Limited" later made its own version of the '50. Whether VSEL inherited stocks of unsold AC100s (which will all have had JMI serial number plates) is possible but difficult to substantiate.
Below, an article published in "Beat Instrumental" magazine, August 1968, publicising the newly-formed "Vox Sound Equipment Limited". Click for a larger image.
"Beat Instrumental" magazine was aimed squarely at the professional and semi-professional musician. The last advert to illustrate an AC100 appeared in 1966.
A couple more Vox Public Address amplifiers - an all valve PA50, long used in a club in Iran; and a PA100 with solid state preamp and valve power amp currently in the States. Thanks to Ashkan and Rob.
Serial number 496, an early "100W Amplifier", now registered here. Thanks to Ihor for the info.
A new page created on an AC100 speaker cab from 1965 - complete and unchanged in all important repects.
8th October (3)
Rear view of AC100 no. 178 and the 2x15" cab (front view below, 3rd October). Note that the socket on these cabs was always over to the left - effectively under the XLR sockets of the amp.
Above, a T60 speaker cab from early 1964. The connector is a round latching Cannon XLR-3-13, also used on early Foundation Bass speaker cabs.
Above, the connector of the 2x15" cab issued with AC100 no. 177. It was originally drilled for a fatter Cannon XLR-3-13, but a small trafolyte panel was used to mount a Cannon XLR-3-32.
8th October (2)
Further pics of Vox PA50 serial no. 7597 now posted here. One of the pots has date code "HN" = August 1966.
AC100 serial number 686 - a "100W Amplifier" - is currently on "Reverb" at the moment, along with what is likely to be its original cab and trolley, though the cab has been altered. Interesting to see labels in red and orange attached to the back panel:
"AMPLIFIER OUTPUT. TO SPEAKER. 8 ohms."
"AC MAINS POWER INPUT. READ BEFORE USE. For use with 1-phase 120VAC 60HZ U.S. electrical service only. Set voltage selector switch of amplifier to 115VAC only. Connect power cable to amplifier before connecting to electrical power outlet. Connect power cable to properly wired NEMA 5-15R electrical power outlet only. NOTE: Ground pin of power cable must contact earthed ground contact of electrical power outlet".
"NEMA" is the "National Electrical Manufacturers Association" of North America.
A couple of shots of AC100 serial no. 178 with a slightly later 2x15" cab (with silver Celestion drivers rather than blue). The amp is probably from autumn 1964 and the cab from winter.
Early AC100s (AC80/100s) with brown grille cloth were normally paired with bass cabinets (also in brown). Only a very few were issued with black cloth for use with the SDL guitar speaker cabs.
Above, details from the public Vox catalogue of early 1964 (sometimes called the "Jumping Beatles" catalogue), probably from January; and the Vox Dealer catalogue of February 1964 (note the printer's runner at foot ../2.64/..). Thanks to Martin Kelly. Images and text are the same in both.
Late 1963 and early 1964 - an exciting time, the sales push was on. Below, an ad and notice relating to the appointment of Reg Clarke. "Crescendo" was a Jazz magazine. Presumably the advert was placed elsewhere too.
Advert placed by Jennings Musical Industries in "Crescendo" magazine, September 1963.
Notice in "Crescendo", January 1964. Reg Clarke stayed on as Sales Manager into the "Vox Sound Equipment Limited" period (mid 1968-1970).
A full-page advert for the Vox AC80/100 from "Beat Monthly" magazine (later to become "Beat Instrumental"), no. 12, April 1964. Note that it also mentions the Beatles' two AC50s.
Below, Amphenol brochures advertising "Qwik" connectors - used by Vox for AC50s and AC100s from mid 1965. The Allied Industries pricelist gives the cost in dollars for various bulk orders. It seems likely that JMI acquired these connectors via the Amphenol factory in Whitstable (Thanet Way, Kent, CT5 3JF), which had been set up in 1961. Whitstable is an hour's drive away from Dartford along the Kent coast.
The former has two Hunts caps with visible date codes:
The leftmost reads "UYT" and the one in the centre of the picture "IUS". Using the "WHITSUNDAY" formula outlined below (entry for 14th September), we get: "604" and "365". The cap. on the left has year first, then week = 4th week of 1966. The one in the middle has week first, then year = 36th week of 1965.
Great shot of the Beatles on stage, Stockholm, 28 July 1964 from this thread. Colour has been corrected.
"Blind Pew and the Sights" at the King's Hall, Ilkley, 1964 or 1965, with an AC100 and two T60 cabs.
A new page with pictures of bands aside from The Beatles with early Vox AC80/100 SDLs - posted here.
Over the next fortnight, pages across the site will be updated and tidied up. None should be inaccessible. The bands A-Z and bass and guitar cab pages have already been done.
The Beatles at the Hollywood Bowl in August 1964. The image has been lightened to help bring out the fourth (spare) AC80/100 lurking in the gloom behind Paul's spare Hofner bass. Click as ever for a larger copy - it should occupy the full width of most monitors.
A late 1950s or early 1960s album of Goodmans stickers and labels is now available here.
It encompasses a number of labels (and box stickers) for speakers that Vox bought in from Goodmans early on. Perhaps the only one relevant to the AC100 (and AC50) is the Audiom 90 - 50 watts, 15 ohms - which went into the earliest Foundation Bass cabinets.
A Foundation Bass cab belonging to AC50 serial number 3490 from 1965 with an Audiom 90 in place. But the speaker may be a later substitution for a Goodmans Audiom 91.
Date codes on Hunts capacitors
Above, a Hunts filter cap from AC50 serial number 1034B (further pics on the AC50 website). Its twin is still in place in the amp. The date code is the three letters: "YIW".
The key to the Hunts code was worked out some years ago on a British valve radio forum with the help of a former Hunts employee.
The system is based on the word "WHITSUNDAY", chosen because it has ten letters, none of which are duplicate. W = 1, H = 2, I = 3, T = 4 and so on, through to Y = 0.
To decipher "YIW": the first two letters give the week of the year, in this case 03, ie. the 3rd week. The third letter gives the last digit of the year of manufacture, in this case "1" = 1961.
Later on, however, the code regularly appears to have been given in reverse order, the first letter being the year, and the second and third the week. This is certainly how it appears on caps in AC100s with serial numbers in the 1900s:
Above, a detail from AC100 serial number 1905. Click for a larger image.
The Hunts code in the pic above is "UYT" = 604 = the 4th week of 1966. Other amps on this page with serial numbers in the 1900s have "UYT" too.
Details of codes on Hunts caps in serial nos 1579 and 1584 will be give shortly.
A page of pics of the J200 now posted here. These will be added to soon with details of the preamp and power transistors.
A small clutch of new AC100s to come.
Quick shots of Jennings J200 serial number 1018, which spent a good part of its working life in Bern - it has Musik Muller stickers, front and back. The latest component date codes immediately visible are on two of the RCA transistors - "0F" = June 1970, so the amp was probably assembled late in that year. Detailed pics will be posted soon.
A new page begun on Jennings (JEI) reverbs. Early ones are extremely scarce. Later (purple) ones are known, however.
If anybody has, or has seen, a new-style JEI B50 or B100 as in the pic above do let me know. The shot is also on the page posted yesterday.
A new page begun on Jennings Electronic Industries in 1973.
A new page posted on the JEI B100 and O100. The two amps had the same power amp as the PA100. The B50, O50 and PA50 also had a power section - 40 watts in this case - in common. One often finds the output of these last given as 50 watts, but that was simply marketing puff. 50 watts was not attainable in an audio amplifier application from two 2N3054s.
The JEI pages will be moved to a site of their own in due course.
11th August (2)
A new page on component date codes in Jennings Electronic Industries amps now posted here.
The process of sorting out the Jennings Electronic Industries pages continues. Three new ones:
Advert from Beat Instrumental magazine, August 1973, for the new style JEI V100, as below. At the Associated Musical Instrument Industries fair, the new line - with brown or woven grille cloth - was unveiled. "JEI" had already become the logo in late 1972.
16th July (2)
A new page now on the Jennings RT10 rotary speaker unit - designed primarily for studio use. 20w power handling (in two 10" Celestion speakers).
The page on the JEI V30 has been tidied up.
15th July (2)
A new page has also been created on the all-valve purple Jennings V100, produced from 1973-1975.
All new pages are registered on the main Jennings Electronic Industries index page.
There is a new page now on the all-valve Jennings AC100, produced for JEI by Triumph Electronics, and new to the range in late 1972.
New pics of the Jennings Electronic Industries pricelist from 1972 have been put up here.
The page on Triumph Electronics has been tidied up. Further info will be added soon.
A new page (which will be one of several) has been started on adverts placed by Triumph in Beat Instrumental magazine, 1967-1972.
The pages on Jennings Electronic Industries amplifiers and speaker cabinets are in the process of being updated.
Additions are now linked up on the index page: adverts and extracts from Beat Instrumental magazine, the J100 combo, the J200, the JEI AC15 and new info on the JEI AC40.
Further additions to come.
9th July (2)
The pages on JEI 1968-1971 are now on this site:
The pages on JEI 1968-1971 are now on this site:
A new page on Jennings Electronic Industries in 1972, principally from material published in "Beat Instrumental" magazine - adverts, short notices, previews and so on. Pages for 1970 and 1971 will be incorporated shortly.
A set of new pictures of serial number 1903 now posted here. Thanks to Vincent.
Over the next fortnight, other Jennings Electronic Industries pages will be updated. A body of documentation has been assembled in preparation on the Vox Supreme website.
A 100W Amplifier currently in Italy has been registered here.
A new page begun on Vox amplifier covers 1964-1967, gathering together info posted at various points on this site.
A new 100W Amplifier has come to light - serial number 682. Thanks to Csaba for the pictures.
29th May (2)
A further Vox "100W Amplifier" has come to light, one of the few amps surviving with a serial number in the 400s - no. 496.
Rudall, Carte and Co. advert in "Crescendo" Jazz Magazine for a "Vox 80 Watt Bass Amp", perhaps an old one, for £100.0.0 - in today's money £1750.
The list price of a new AC100 - a Mark 2 - in Nov. '65 was £105.0.0.
Advert placed by Jennings Musical Industries in "Crescendo" magazine, September 1963.
Notice in "Crescendo", January 1964. Reg Clarke stayed on as Sales Manager into the "Vox Sound Equipment Limited" period (1968-1969).
23rd April (2)
Pics of a Triumph-made AC100 paired with a JMI Supreme cab added on this page. Thanks to Magnus.
New pics of a Vox PA50, or to give it its correct designation, MC50 mark 3 posted on this page. Thanks to Will.
Pics of serial no. 1580, in excellent original condition, added here. Thanks to Mike.
Working on the Vox Supreme website at the mo. A series of AC100 updates to appear soon though.
Some observations on Jennings Electronic Industries items (1968 - 1975). For the main pages on JEI amps and cabs, click here.
Above, two Jennings B3 bass cabinets - 50W handling. Both have 8ohm Goodmans Audiom 15" speakers (red label). Serial no. 263 has rounded corners, the old style logo, and reddish cloth. Serial no. 290 has squared corners, the new-style logo, and brownish cloth.
The JEI price-list of 1972 shows that the B3 cabinet cost £71.00. Click as ever for a larger image. The Bank of England inflation calculator indicates that this would be equivalent to around £860 today - not a small amount.
Above, the JEI J40 combo amplifier (the solid state version of the JEI AC40). Note the solid back panel with cutout - much as the back panels of the Beatles' AC50 cabs that Dick Denney had helped design some eight or nine years earlier.
Pics of the sympathetic restoration of serial no. 1857 posted here. Thanks to Aart.
Further pics of serial number 424, a late cathode biased amp, added here.
More on cables - above, most likely a speaker cable for a Vox Conqueror (ie. between amp and cab), missing one end. The type of wire is the same as that used for AC30 footswitches and the signal feeds inside AC100s.
Couldn't resist popping this up straight away. The Swingin Sting Rays with an array of Vox gear in 1965: two large box Foundation Bass sets (the cabs with roller trolleys), an AC100, a pair of LS40 speakers, and a Vox Phantom guitar. The other guitar is a Burns bison. Pic from this page.
12th February (2)
Logos from three Vox AC50 covers from different eras. Left: c. 1965; centre: c. 1967; right: probably VSEL or VSL. Pictures of the handle trims to follow. The first has maroon leather; the second, tan leather; and the last, none. The 1967 cover has thin vinyl, typical of the covers for solid state amps. The VSEL or VSL is much thicker and of a different type.
12th February (1)
Above, an AC30 from mid 1964 - copper panel and silver Celestion T1088s, so certainly after May 1964, and in view of the basketweave tolex (rather than smooth charcoal), likely to be summer 1964. Original chocolate brown plasti-leather cover shown in the second picture.
Chocolate brown covers also survive for an AC80/100; an AC50 mark 1; and PA columns (LS40). Towards the end of 1964, covers became uniformly black. Most had VOX logos. However, it is clear from survivals and early photos (of The Who at Richmond) that some black AC100 covers were issued without.
11th February (5)
A Vox Echo SV, sold on ebay towards the end of 2016. These were assembled by Triumph for Vox from 1966-1967 (and appear in the catalogues of those years). The styling matched the PA ("mixer") amps in the same range.
11th February (4)
This AC100, recently on sale, is a composite. The box, with serial number 586 on its back, came from one source. The amp chassis, a "100W Amplifier" (chassis no. in the 1400s) came from another. The black panel was apparently bought on ebay and added later. The original grey panel is in the UK. Cab and trolley are repros. Earlier pictures of the amp are here.
11th February (3)
Serial number 1540, also on the market currently. Assembled for Vox by Triumph Electronics, so the number doesn't mean that much - but a nice amp, currently in Germany. The typical unpainted transformers used by Triumph are visible in the second pic. above. The runners in the wooden case have been repaired. Older pictures of the amp are here.
11th February (2)
Serial number 785 - possibly 785 at any rate - is up for sale. The serial number plate is a repro, but may (though there is no guarantee of course) simply replicate the original. The speaker cab has new grille cloth; the trolley is from an American Super Beatle. The rectangular Cannon XLR connector may have been renewed, but an identical one must have preceeded it, as there are no stray holes for a round Amphenol. Round Amphenols had come in, where cabs are concerned, by serial no. 800. See the entry below for 5th Feb.
11th February (1)
The server went down for a few days earlier this week, but everything should be back to normal now.
5th February (2)
A brief return to early Vox plasti-leather covers, the two below for T60 amps: one in maroon, the other, needing some restitching, in racing green.
Coloured covers for T60 cabs have yet to come to light. We do however have one in brown for the 2 x 15" cab that accompanies AC80/100 number 177.
5th February (1)
(1) Both cab and amp of AC100 serial number 800 have Amphenol connectors.
This therefore provides a useful terminus ante quem for stray cabs with a rectangular Cannon XLR.
(2) Only a handful of amps survive with the original factory-fitted cable running from the output terminal block to the XLR on the backboard. Below, serial number 392.
The cable (as fitted at the Burndept works) is screened single core (steel), 1/8 inch diameter. Lengths were also used for the feed from the preamp to the power valves (in the second picture, one can see the twin feeds passing through the grommeted hole by the capacitor), and for AC30 footswitches. Techs, presumably throwing up their hands at the apparent flimsiness of it, seem to have replaced the backboard cable in most amps.
It's worth noting that Vox, being Vox, made the original cable extremely short - 7 1/2 inches long. The mains feed into the amp from the backboard socket was similarly short too, giving extremely restricted play to the backboard when unscrewed.
4th February (2)
A couple of notes. First, serial number 289 has been reported as having a grey control panel. Interesting if true, as the panels of serial numbers 276 (hand-stamped plate) and 306 (machine-stamped) are black. But the amp could have been made by Triumph - and Triumph used serial number plates in a completely random fashion. The type of plate - hand-stamped or machine-stamped - has still to be determined.
Second, two largish gaps remain in the sequence of known amps at the moment: 430-501, and numbers in the 600s. This could just be accident - a result of the sometimes piecemeal way in which info comes to light. But simply to float the question: were some of those amps reserved by JMI / Vox for loan?
4th February (1)
A couple of new amps to signal - serial number 424, mentioned yesterday, and serial number 2134, the highest serial number definitely known:
Above, serial number 424, a late cathode biased amp produced for Vox at the Burndept factory, mid 1965. The amp was mentioned on several VoxTalks threads in the 2000s, but sank out of sight.
The lowest two panels are perfectly readable, even though the image has been expanded beyond its natural size. Serial no. is 02134, and the Rating: 319. Note the double pin corner protectors.
Below, the chassis numbers of two late cathode biased AC100s, restamped at Burndept. The amps in question are serial nos 424 and 430.
Originally 1027, changed to 1130
Originally 1044?, changed to 1135
Perhaps at serial no. 400 someone decided to start chassis numbers off at 1100. Alternatively, the person in charge of the stamping machine may have got things wrong. The lowest chassis number to have come to light so far in a fixed bias amp is 11xx, the last two numbers unfortunately illegible.
A better picture of the backs of the Beatles' speaker cabs from Milan, 24th June 1965. What seems to have happened is that the cabs issued in August 1964 were refurbished (new logos at the very least) and provided with new chrome trolleys.
The last time the old trolleys were seen in public was at the NME Pollwinners concert, Wembley, 11th April, 1965.
Part of Peter Noone of Herman's Hermits standing in front of one of the Beatles' cabs with an AC50 on top. Note the basket top to the trolley and the narrowness of the parallel side bars.
28th January (2)
A long shot from back of stage at Shea. In view is the amp used by John - the early thin-edged AC80/100 originally issued to Paul, and one of the speaker cabs from August 1964. Note that the speaker connector is on the lowest back board, rather than in the centre, which was the norm in standard production cabs.
Click for a larger image. A great grab from the restored film of the sound engineers at Shea.
28th January (1)
Jack Bruce with Graham Bond playing through an AC100 and two 2x15" cabs, c. 1966. Picture from this site. Photographer: John McCoy.
"The Blue Rockets", a band from Eygelshoven in the Netherlands, with an AC100 SDL behind.
The pic above, posted a little way below a few days ago, shows Bill Wyman with the AC80/100 he is first seen with in April 1964. The photographer, Stanley Bielecki, is clear that it was taken at the Playhouse Theatre - and it certainly was as pics of the Beatles taken there show. The Stones rehearsed at the Playhouse in preparation for their BBC World Service broadcast on 31st October 1964.
The amp was evidently still going strong six months after Bill received it.
15th January (3)
Below, two screengrabs from the documentary on Screaming Lord Sutch and the Savages, made in early 1965 - scenes shot at the Lotus Ballroom, Forest Gate, London, September 1964.
A thin-edged AC80/100 and early bass cab with perspex logo. Note that the bassist is plugged into the second (the low) input, as Paul McCartney did too. The film as a whole is available on the BBC website.. Further grabs will be set up on a separate page.
15th January (2)
Just for interest, inverted details from the largest available image of the backs of the Beatles' amps, Finsbury Park, Astoria, Christmas Show rehearsals - late December 1964.
Above, Paul's old amp (his first AC80/100) reboxed in a new thin-edged box, but used by George in this instance. Note the 8-line serial number plate. The amp sits in the basket top of one of the old SDL trolleys.
A newer amp used for the show by Paul - still cathode biased, thick edged box with no corner protectors. The serial number plate has 9 lines of text.
15th January (1)
Bill with his small-box thick-edged AC50 and Foundation Bass cab at the BBC probably in the second half of 1964. Note the AC30 to left. Bill generally used an AC50 at smaller gigs/venues, and for recording. His first AC50, seen in April 1964, was in a thin-edged box.
The Stones rehearsing in October 1964. Note that one can just see the back of Bill's AC80/100 at left - two circular Cannon speaker output sockets one above the other. For more on this amp, see this page.
Sounds Incorporated on stage at the Empire Pool, Wembley, 20th Nov. 1964 - the "Glad Rag Ball" organised by London University. A pic. of Gene Vincent and the Londoners from the day is posted lower down on this page. Just visible behind Sounds Incorporated are the early AC100 SDL, the large-box AC50, and the AC80/100 on the drum riser.
A great pic from Getty Images of the Rolling Stones on stage at the Olympia Theatre, Paris, 20th October, 1964.
Picture taken by Roger Kasparian at the Olympia - the connectors on the back panel of the AC80/100 are just visible. Click for a slightly lightened copy of the image.
The Stones at the ABC Cinema, Chester, 14th September 1964. Bill's two Foundation Bass cabs are at the near and far sides of the stage, the AC80/100 on the far one, largely obscured by Mick Jagger. The AC80/100 and cab immediately to our left of the drums presumably belonged to Inez and Charlie Foxx's band, also on the bill, and regular Vox users.
A great composite of The Move at The Marquee Club in 1966 giving something the chop. At least three AC100s are on stage.
A new picture page on the Yardbirds in "Blowup" now available here. The section was filmed at Elstree, the set replicating the Rikki Tick Club in Windsor. The band had three "100W Amplifiers" and a selection of cabs, presumably provided for the occasion by JMI. The blue hangtag of one of the 2 x 15s can be seen fleetingly.