The Jennings Musical Industries "Vibravox"
1957 - 1960
What's in a name? Below, the three iterations of the Vox "Vibravox" unit, designed in late 1957 for use with "any amplifier", its electronics incorporated early on in the AC1/15, AC2/30 and AC/30. The AC30/4 represents a later development. More of the circuitry later.
Although the design of the unit (outward appearance) was protected in British Law ("registered"), the name had in fact already been coined - from 1949 in the USA there were the Danelectro "Vibravox" amplifiers, a single speaker version much as the AC2/30 in terms of proportion, and later a twin. See the pictures below.
Evidently there was no difficulty: Vox regularly referred to the "Vibravox" in its AC30/6s through to 1964. The Danelectro amps, however, are very much of their age and have little in common from an electronic standpoint with anything produced by JMI.
Fingers crossed that an early Vox "Vibravox" comes to light at some point. For an analysis of the circuit and an eye-witness description of a unit c. 1960, see this page.
"Accordion Times", January 1958. First version of the Vibravox. Note the unit is "Registered", a protection of the design in law extending solely to outward appearance and cosmetics. Electronics and technical aspects were covered by other protections, which also had to be applied for - e.g. patents and so on.
"Accordion Times", March 1958. Second version.
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1959, reverse of the JMI flyer for the AC15. Martin Kelly has kindly pointed out that the vibrato switch on the Vibravox unit was pretty much identical in form to one used on certain Jennings Univox keyboards, the only significant difference being the presence of the "OFF" position on the latter. The Vibravox unit, as pictured, had a footswitch.
Vibrato switch on an early Jennings Univox J6.
Paragraph on the AC15 vibrato on the front of the flyer from 1959. Note that the Vibravox circuit is described as being "patented". No patent exists, however, in the old Patent Office records, so whatever application JMI made never came to fruition.
"Accordion Times", April 1960. Third version, with black panel.
Early to mid 1961 - from the brochure issued to publicise the AC30 Twin with Celestion blue speakers.
A Danelectro "Vibravox" amplifier from 1949.
The later format of the Danelectro "Vibravox" twin.