VOX AC100 - UPDATES AND NEW INFO
June to September 2024
22nd September
The page on the intriguing early Westrex-made AC80/100 with a grey control panel has recently been been revised.
Early AC80/100 long with grey control panel.
The amp's chassis has two unusual features in common with that of serial number 182: red RTC electrolytic capacitors (a single one in the case of number 182) as replacements for the original Dubiliers, and a dome voltage selector. Whether these things are simply coincidence is not clear at present.
Serial number 182, from a set of pictures taken before the amp was acquired and refurbished by Jim Elyea.
All that can be observed for the time being is that red RTC capacitors were regularly used by Triumph for the AC50s it produced for JMI. The RTC date codes have not been fully deciphered yet.
20th September
A schema of the back panel of an early AC80/100 that turned up in Yorkshire some years ago. Although most of the original fittings are lacking, the tell-tale screw holes are still there.
Originally there was only one speaker socket (the outermost of the two now present). The inner one was made later, after the serial number plate had been removed. The Bulgin mains socket at right may well be original. Some later addition left its mark in the centre of the panel.
The closest relative in terms of general arrangement is serial number 174 - see below. Back panels in the 170s are fairly eccentric, serial number plates rarely centred.
The AC80/100s currently not accounted for in the 170s are 170, 171, 172, 176 and 179.
Serial number unknown, probably in the 170s. The original hole for the speaker socket at left was probably enlarged when the inner one was added.
Serial number 174. Originally the back panel would have had only the Cannon speaker socket lower left, the plate, plaque, and mains socket at right. Everything else added later.
19th September
Below, recently posted on the AC50 website, the two types of warning plaque used on early AC50s, the first for only a short time. Type 1 has so far come to light on only one early AC80/100.
An overview of surviving early AC50s - single channel, two inputs, thin-edged cabinet - can be found on this page.
AC50s issued early on to The Beatles and The Dave Clark Five evidently had no warning plaques of any sort. Nor for that matter did Paul McCartney's first AC80/100.
Type 1: AC50 serial numbers 1004 and 1005.
Type 2: AC50 serial number 1034 through to amps issued in early 1965.
9th September
Thanks to Colin, below, his father's "Musicland" pricelist of September 1964 and the catalogue it accompanied, the newspaper-format "Vox: Precision in Sound" catalogue.
The two were drawn up in tandem after the Russell Hotel Trade Fair of late August 1964. Pictures taken at the Fair show various stacks of what must be an earlier pricelist (probably one from the summer of '64), and the colourful dealer catalogue "1964/1965" - see this page for coverage.
The page on "Musicland" has been updated.
"Musicland" pricelist and Vox catalogue of September 1964.
The rear of the pricelist with printer's runner - "PL/9.64/10.M/C.P.C/J.P". The runner at the foot of the version of the list printed for JMI (with "JMI" at head on the first page) is "PL/9.64/5.M/P.C.B/J.P"
5th September
Thanks to Paul, some pictures coming of an interesting "100W Amplifer", no serial number plate ever fitted to the back panel.
22th August
Further pictures of AC100 serial number 1156 have now been set up on this page. Thanks to Paul.
Details of the chassis of AC100 serial number 1156. The latest visible component date code is October 1965.
19th August
Thanks to Paul, pictures coming shortly of AC100 serial number 1156, early 1966, an entry to be provided on this page.
6th August
An old picture of a MC50/6 from 1966/1967 sold in Germany c. 2008. JMI regularly advertised the MC50/6 and MC100/6 in brochures, catalogues, and pricelists produced for the German market.
4th August
Thanks to Devin, a general view of an AC100 with a serial number in the higher 400s, or very low 500s. The chassis number is 01163. The prefatory "0", which often imprinted incompletely as a backwards "C", appears to have been brought in with the new fixed bias "100W Amplifier".
All cathode biased amps that have come to light so far have four digit chassis numbers.
5th July
Thanks to Ed, pictures of AC100 serial number 319, black panel, Woden mains transformer with the date code "KV" = October 1964, the amp presumably ready for sale in early 1965.
There was evidently some overlap between black and grey panels. Serial number 320 has grey, serial number 330 is said to have black.
Grey panel amps had new-style dome voltage selectors from factory. At present, but for one (serial number lacking), all black panel AC100s have the old-style link selector.
1st July
Thanks to Damion, pictures of an AC100 from the third quarter of 1966, serial number probably in the mid to high 1800s, have been added here.
25th June
A note on the transformers in AC100 serial number 1853. These are of the black shroud variety. Various stabs have been made at identifying the manufacturer, but nothing provable has come to light so far. The bare facts are that JMI commissioned two sets of transformers from the company in question in 1965, one for AC50s, the other for AC100s, and later, in 1967, sets of transformers for the new solid state range of amps. Selmer also used this manufacturer for a short time in 1966 for its larger amps.
The format of the date codes, stamped in white on the laminations, tends to suggest that the manufacturer was not one previously used by JMI - ie. not Haddon, Woden, Parmeko, Albion, JD Electronics, Drake, or the (unknown) manufacturer used by Triumph.
Twickenham Transformers, which later became Lemark, is a possibility.
The output transformer pictured below has "INB", the mains transformer "IJB". Codes of this type are most visible on AC50 chokes. It is clear from surveying a spread of these codes that the first letter is the year - "H" = 1965, "I" = 1966, "J" = 1967.
AC100 output transformer (1966)
Dimensions of the lamination stack: 2 1/2" tall, 3 1/8" wide at front, 3 1/2" deep.
JMI part code: 66776
Manufacturer's date code: "INB".
AC100 mains transformer (1966)
Dimensions of the lamination stack: 2 1/2" tall, 3 1/2" wide at front, 4 1/2" deep.
JMI part code: 66775
Manufacturer's date code: "IJB".
Transformers removed for the cleaning of the chassis of AC100 serial number 1853.
Fixing bolt for the transformers, 2BA, three inches long, threaded in the last 1/2 inch only.
12th June
Thanks to Steve, some pics of the power section of a MC100/6 public address amplifier from 1967. Date codes of the Hunts caps are "UWW" and "NWY" = 11th week of 1966, and 1st week of 1967 for their manufacture. Some details of other MC100/6s can be found on this page.
10th June
A few details on AC100 serial number 1853: chassis number 02028; latest visible component date code "XE" = May 1966; Mullard XF3 EL34s dated "B5F4" = 4th week of June 1965.
8th June
Just to note that AC100 serial number 1853, probably produced in the second quarter of 1966, has recently emerged from hiding. Further pictures to follow soon.
