November 1965: Dick Denney visits the Thomas Organ factory in Sepulveda, California, to advise on the pre-production American-made solid state range. JMI, it should be said, already had "transistorised" units of its own at that point - principally, the T60 bass amplifier, and the preamp of the new 100W PA amplifiers issued in August 1964. For amplifier manufacturers of the time, the biggest difficulty was obtaining consistently reliable transistors for power sections.

Late 1965 / early 1966: Thomas Organ reportedly sends a solid state amplifier to the Vox Works at Erith for testing. Reception is cool.

Early 1966: the 4-series and 7-series amplifiers are designed and produced - transistor preamp, valve power amps. The Beatles receive early production (not prototype) 7120s in mid April.

Mid 1966: Design and prototyping of the new range of fully solid state amplifiers. Meanwhile the 4-series and 7-series amps are promoted as the "latest thing".

Late August '66: a promotional Vox Conqueror exhibited at the BMII Trade Fair at the Russell Hotel, London, 22nd to 26th August, 1966.

The Conqueror exhibited at the Russell Hotel, London. For more on the Fair, see this page. The Guardian newspaper reports that orders were taken for the "new range" of transistor amplifiers. These will not have been met until the Spring of 1967.

The JMI brochure for the Australian market reproduces the first attempt at a footswitch. Note that the "Virtuoso" at this point was the "Supreme". What we now know as the Supreme was called the "Beatle".

Detail from the Australian catalogue, late 1966.

Late 1966: a small number of pre-production amplifiers are made in the Vox Works at Erith. A surviving pre-production Dynamic Bass retains its original inspection tag, dated 12th January 1967.

Pre-production Dynamic Bass

Late 1966 / early 1967: the pre-production amps were given to bands to try. Manfred Mann and Blossom Toes were issued with Supremes. Manfred used his until c. 1970 with a Vox 4120 speaker cabinet.

Manfred, Berlin, 1967. As in all pre-production amps, the speaker socket is at left on the back panel, the mains socket far right.

Early January 1967: the announcement is made in "Beat Instrumental" magazine that the new range would be available at the end of the month. But this did not happen.

Probably late January / early February 1967: the range is redesigned, cosmetically and electronically. Feedback from the bands on the pre-production models had doubtless raised some difficulties.

February and March 1967: advance production of the new designs begins. By late April, around 100 Defiants had been made.

Late Feb. / early March 1967: the new solid state amps are "a secret", for the continental market at least, until the Frankfurt Musikmesse. The German catalogue (dated March '67) is printed to coincide with, or follow, the Fair.

"Midland Beat" magazine, March 1967. The Frankfurt Musikmesse took place from 26th February to 2nd March '67.

Mid March 1967: The Stones are issued with two standard production Supremes and a Super Foundation Bass amplifier. See this page.

April 1967: the new JMI pricelist for the UK is issued. "Beat Instrumental" magazine relates elliptically that the range is now available.

For some material on production, see this page, which has recently been updated.