The AC2/30 - late 1957 to spring 1958
Four or six inputs; two EL34 valves; fixed bias.
"Melody Maker" magazine, 8th March, 1958. Bulletin no. 3 of the JMI Electronics Division.
Produced in late 1957 - Spring 1958. The amp came in two varieties: the standard model with four inputs, lacking Vibravox; the other with six inputs, Vibravox built in, the additional two inputs being for the Vibravox channel. Descriptions in the adverts (see below) occasionally conflate the two.
The speaker was a 15ohm 12" unit - probably a Goodmans Audiom 60. See the "Melody Maker" advert for 22nd February 1958, below.
The amplifier's control panel was black and the knobs white.The cabinet had a split front with diamond grille cloth fixed horizontally. There was a cut-out on top of the cabinet for the control panel and a vent to dissipate heat from the valves. A solid luggage handle was fixed to the cabinet's right-hand side.
The AC2/30 was a sort of multi-purpose amplifier - aimed at accordionists, lap-steel players, and guitarists. It was taken up by a number of famous musicians: Jack Emblow and Henry Krein were both pictured with one, Bill Kent, and Bert Weedon (no pictures of the latter at present). Dick Denney is also said to have used one at the Embassy Court ballroom in Welling.
Judging by the advert above, Jennings was evidently proud of the built-in vibrato/tremelo - "gives such a startling effect that tape recordings have been made and will be sent on request...". The circuit diagram for the AC2/30 is OS/003.
JMI circuit diagram - UNDATED - "AC.2 30Watt Amplifier. OS/003." An octal socket was provided for the plugging in of an external Vibravox unit or a Radio Tuner. The complement of valves is: two ECC82s (12AU7) in the preamp; two EL34s for output; and a GZ34 rectifier. The EL34s have around 400v on their plates, and a fixed bias of -30v. Thanks to Glen Lambert for the image.
"Melody Maker" magazine, 16th November, 1957, and detail. 55 gns for the standard model, 62 gns for the model with vibrato (vibravox). The logo takes this form on the amp illustrated in the "Accordion Times" advert, December 1957, page 31, below.
"Accordion Times", December 1957, page 24. The logo is of the same form in the advert in "Melody Maker", 11th Jan. 1957, below.
"Accordion Times", December 1957, page 31. As in the "Melody Maker" illustration above, "VOX" in large letters diagonally across the upper panel. The four controls indicate the amp is a standard model - two volumes, one bass, one treble.
"Melody Maker" magazine, 11th January, 1958. Bulletin no. 1 of the JMI Electronics Division. The AC2/30 is last in the row of thumbnail sketches.
"Melody Maker" magazine, 22nd February, 1958. The prices are still 55 gns (standard), 62 gns (vibrato).
"Accordion Times" magazine, March 1958.
"Melody Maker" magazine, 12th April, 1958, and detail.
"Banjo, Mandolin and Guitar" magazine, May 1958. The series of JMI Bulletins is different from the one published in "Melody Maker" magazine.
Raggett's Hall, Maidstone, 1958. The "VOX" logo has gone, but the small plaque underneath - "Jennings" (?) - remains.
"Accordion Times" magazine, February 1959. The Francis Wright Quintet.
For further pictures of the AC2/30 in use on stage (venues in Kent) in 1957 and 1958, see this page. It has been ventured that "only a handful were made". This may need to be revised as at least 5 different ones are captured in contemporary photographs.
MELODY MAKER, February 1958 (above): VOX AC2 AMPLIFIER 55 gns. A 30-watt output at 15 ohms, A.C. mains operation Hi-Fi amplifier, fitted with three input sockets: (a) for crystal mikes, (b) for ribbon-moving coil mikes, (c) for gramophone pick-ups, radio tuner units and high level signal inputs. There are two volume controls for inputs (a) and (b), and one volume control for input (c), in addition to separate bass and treble controls. (Fitted with internal vibrato. 62 gns.)
3 inputs, 3 volume controls, 2 tone controls (bass and treble). Note that the amplifier in the descriptions below has PAIRS of input sockets. There is no explicit mention above of guitar or bass.
ACCORDION TIMES, March 1958 (above): "Vox Hi-fi Amplifier AC2/30 has 30-watt output; A.C. mains, 12in. heavy-duty speaker; three pairs of input sockets, each with its own volume control, also two separate overall bass and treble controls. Standard model: 62 gns. Fitted with internal vibrato: 70gns."
The 6 inputs, 3 volume controls, and 2 overall tone controls (bass and treble) evidently describe the Vibravox model. The vibravox circuit presumably required a further control on the control panel, bringing the total to 7.
Detail of the Vibravox from "Accordion Times", March, 1959.
JENNINGS CATALOGUE, 1958: "Vox Hi-fi Amplifier AC2/30. 30-watt; A.C. mains (200v to 250v), with four high-inpedance input sockets - two for use with crystal mikes, guitars, electro-bass, accordions etc., and two for use with guitar, electro-bass, radio-tuner units, radiograms and recorders. There is a volume control for both pairs of inputs, also two separate bass and treble controls. The amplifier is housed in a robust case fitted with a 12-in. heavy duty loudspeaker and also, if required, a VIBRAVOX unit."
4 inputs, 2 volume controls, 2 tone controls (bass and treble) describe the standard model.