100W PA unit (solid state)

The earliest known photo of one of these amps (with reverb) currently known, the "Jennings Electronic Developments" display at the Russell Hotel Trade Fair, late August 1968.

Initiially, because consultantcy and design work were primarily in view, Tom named his company "Jennings Electronic Developments" - see this page. In late summer 1969, its catalogue and range of activities having expanded considerably, he recast operations as "Jennings Electronic Industries".

But the PA100 had evidently been designed while Jennings Musical Industries (JMI) was still in existence. The detail below is from the Russell Hotel trade fair in August in 1967 - a pre-production Vox version sits on top of a large Gyrotone Mark IV.

The photograph as a whole is available on this page of the Vox Supreme website.

Units were offered with or without reverb, sales of the former being comparitively slow. Only one example has come to light so far. The PA50 also sold in relatively small numbers.

Construction of the Jennings solid state amps became modular by early 1969. The PA50, PA100, J50, O50, J100 and O100 all had the same format of chassis and wooden outer case, the 50W amps having one type of power section, the 100W amps another. A picture page on serial number 1045 can be found here.

In terms of the main driver and power resistors, the 100 watters had one each of: RCA 40406, 40407, 40408, 40409, 40410, and two 40411 (main power transistors). More on the power section of these amps to come.

Until recently it seemed as though serial numbers began at 1000. That is clearly incorrect (see the entry for number 931 below). Did they begin at 900? If 100 had been the starting point, then that would mean that over 800 had been sold by early 1970, which is incredibly unlikely.