The Vox PA50SS - Public Address amplifier
50w, solid state, four channels, master volume
Detail from the "Vox Sound Limited" catalogue of August 1971.
As has long been known, design of the PA50SS, in company with the PA100SS, goes back to JMI days, certainly early 1967, perhaps even late 1966. An overview of the early material can be found on this page. The page on the Vox PA100 is here.
A detail of testing at the West Street Works in Spring 1967. At left, a PA50 chassis, two speaker sockets on its back panel. PA100s had four.
So far as one can tell, few amps made their way to market early on however. Production began in earnest under "Vox Sound Equipement Limited", the company brought into being by Cyril Windiate, Reg Clark, and others, in the summer of 1968 following the collapse of JMI.
The first inkling we have at present of sales is the presence of an entry for the PA50 in the pricelist of February 1969:
VSEL pricelist of February 1969.
It is probably no coincidence that February 1969 was also the moment when the first major changes to the circuit were noted on the circuit diagram (schematic).
Above, a detail of the "Vox Sound Equipment Limited" circuit diagram for the PA50SS: changes and dates, running from May 1968 through to July 1970, by which time "Vox Sound Limited" had come into being. On VSL, see this page.
Detail of the display at the Russell Hotel, August 1969, from left to right, PA50, Midas Gyrotone amplifier, and the a PA100. Behind the three is a further Midas.
In contrast to its bigger brother, the PA100, production of the PA50 ran through to "close of play" under "Vox Sound Limited", the company that had in turn succeeded VSEL in January 1970.
Around 350 PA50s were made (versus 300 PA100s). Serial numbers began at 1000. As with the solid state range in general, PA50s were incredibly neatly and carefully made.
An overview of surviving PA50s
A series of details of a PA50SS from 1971 (serial number 1289) can be found on this page.
Serial number 1157
Thanks to Steve, pictures of VSEL PA50SS serial number 1157, metal grilles still across the vents - plastic was introduced by VSL in 1970.
Serial number unknown
Vox Sound Equipment Limited. Note the wire grille on the underside. The string round the box is silver.
VOX SOUND LIMITED (1970 - 1972)
Serial number unknown
Probably Vox Sound Limited. Plastic vents now.
Serial number 1289
Vox Sound Limited. Serial number 1289. For further pictures, see this page.
Serial number 1310
Vox Sound Limited. Plastic vents now top and bottom. Serial number 1310.
Serial number 1320
Vox Sound Limited. Serial number 1320.