VOX AC100 - UPDATES AND NEW INFO
2025
23rd January
Just to note that pictures of AC100 serial number 736 (00736) have recently been posted on FB. The entry for the amp - on this page - has been updated.
20th January
Thanks to Angel, pictures of a Triumph / Jennings AC100 from later 1971, possibly 1972, in superb original condition. The amp is one of a number sold without logo and serial number plate. The main page on the Jennings AC100 can be found here, the amp below pictured in the section towards the end of the page.
19th January
Thanks to Marc, a couple of new pictures of AC100 serial number 496, late summer 1965.
8th January
Two further sightings of early JMI Line Source 60 public address speaker columns (4 x 12"), late 1965 / early 1966, a single with the shop plaque of "Musikhaus Hummel" in Frankfurt but currently in the USA, brown grille cloth, type of speakers unknown; and a set of two, currently in Europe, original stands present. All three have the distinctive band (dropped later on) across their fronts. More on Line Source 60s can be found on this page.
Thanks to Kevin for signalling the existence of this column. If the brown grille cloth is original, which it may (just) be, then a very late instance.
Thanks to Joop.
2024
29th December
Vox Line Source 40 (LS40) public address column speakers in America, late 1964 to late 1965. The earliest dated picture that has come to light so far is from March 1965 (below). The LS40s in view are English-made, flown over to the US for the Thomas Organ Company to distribute and sell:
March 1965, pictured with Hal's Vox AC4 and Stroller guitar.
The columns will have had "Jennings Musical Industries" identification plates on their backs, no mention of Thomas Organ. An overview of JMI's production can be found on this page.
For its catalogues, Thomas, as was its wont, gave the columns a fancy "Swinging London" name - the "Grenadier" - and designated the model for its inventories as the "V-1-20". Below, a detail from the pricelist of April 1965:
In the pricelist of September the V-1-20 is $295.
Although English-made equipment remained the norm through to the autumn of 1965, Thomas had in the meantime made good progress with plans for its own production lines of Vox equipment, primarily to cut the costs of shipping (though that evidently was not the only reason). Dick Denney duly went to Sepulveda to advise. The story of Dick's time there in late October / early November 1965, and an outline of the various matters discussed, can be found in Appendix 3 of the "Vox Story", ed. Denney and Petersen (1993), which gives a transcript of the Thomas report of the visit - fascinating reading and key to understanding how Thomas got its own production going.
On page 144 the matter of speakers for Line Source columns comes up. The text is worth quoting:
"Various speaker samples were compared to those used by Jennings in this application [the LS40]. No American speakers were found amongst the available samples which gave identical tone and performance to the English version. Here it was not so much a case of speakers being better of worse, but it is our desire not to alter the present sound characteristic of the English unit. Speakers have been purchased from the English source for the first releases of domestic production and we will continue to sample speakers from domestic speaker manufacturers until a satisfactory equivalent is obtained."
The English speaker manufacturer was of course Elac, and these were fitted to the first American-made columns - the "V-9". Below, some examples. The columns have Thomas identification plates at back, standard Thomas textured vinyl (not basketweave), paper stickers inside bearing the serial number of each column, and Elacs, as mentioned. Thanks to Ihor for the first three pictures.
No serial number was stamped on this plate.
Column number 992082.
The V-9 is on the right: main case made of plywood, the baffle and back panel chipboard (particle board), replicating the construction of the English-made cabinets of 1965.
Details of another set of V-9s, pictures thanks to Glenn - the serial number 992323 machine-stamped on the metal plate:
Rear, showing the closed back.
The serial number plate.
The highest column number (on the paper stickers) known at present is 992999. If the sequence began at 990000, then Thomas is likely to have made and sold around 500 pairs from late 1965 to around mid 1966. If on the other hand the starting point was 992000, which is perfectly possible, then of course around 400 made. During the course of 1966 changes that are not really germane here were brought in, and the model redesignated as the "V-1091", which is perhaps the most familiar version of the model.
20th December
A note on white warning plaques. The earliest AC50s with known serial numbers - 1004 and 1005 - were fitted with a type of plaque (Type 1) visibly different from the type of plaque that came shortly afterwards and remained standard into 1965 (Type 2). The earliest Type 2 plaque known at present occurs on AC50 serial number 1028 [*not number 1034 as previously stated].
The AC50s issued to The Beatles and The Dave Clark Five evidently had no warning plaques of any sort.
Type 1 plaque, AC50 serial number 1004. The same type is also found on AC50 serial number 1005.
Type 2 plaque. AC50 serial number 1034.
The same quick transition from Type 1 to Type 2 can be seen on AC80/100s. Bill Wyman's first amp - serial number 150 - had a Type 1 plaque, the change to Type 2 taking place by serial number 162.
Type 1 plaque, Bill Wyman's first AC80/100. Although the print resolution is low, note the amount of white space above "WARNING".
Type 2 plaque, AC80/100 serial number 162.
Type 2 plaque, AC80/100 serial number 178.
25th November
Thanks to Phil, pictures of Jennings AC40 serial number 1197, speakers dated November 1971, can now be seen here. Pics of Jennings JV serial number 1188 to come.
AC40 serial number 1197 (at right) with JV40 serial number 1188.
22nd November
Copied over from the Vox AC30 website. Published in "Music Maker" magazine, April 1967, "The Beakles", miniature drum kit, AC30s, AC100, and guitars made by Mick Bennett of JMI. Mick was responsible for prototyping many of JMI's guitars, cabinets, and cases through to 1968.
19th October
Thanks to Daniel, pictures of AC100 serial number 2108, mid 1967, have been added here.
AC100 serial number 2108.
18th October
Just to add in relation to yesterday's entry, "Emihus" zeners first come in towards the end of 1965. Serial numbers 796, 902 and 917 still have gold-coloured zeners made by "International Rectifier".
17th October
Some notes on the bias circuit of the AC100 mark 2, later 1965 through to 1968.
Detail from the circuit diagram for the AC100 mark 2.
As in the "100W Amplifier" of late summer 1965, the bias voltage was clamped by a pair of zener diodes - see this page. For the AC100 mark 2, JMI turned to "Emihus", a subsiduary of EMI based in Glenrothes. The "Hus" part of the name was the original owner - Hughes International (UK), part of the Hughes Aircraft Corporation.
The 20v diode across the width of the board was a "HS2200", the 15v diode across the two solder terminals a "HS2150".
Detail of AC100 serial number 1579.
Below, a detail from the "Emihus" specification sheet, the columns left to right being: part number; zener voltage; tolerance (in %); max. zener current (unspecified); dynamic resistance (in ohms); max. dissipation (in mW); type of connection (A1 = axial, flying leads).
Detail from the Emihus spec. sheet.