The Vox PA50
Produced for Vox under contract by Triumph Electronics in Purley. Triumph also produced AC50s for guitar and bass through to early 1965.
Serial numbers of the PA amplifiers ran as part of the same series as the guitar/bass amps.
References to PA units in music paper small ads are being collected together here.
First generation Metal-Clad amplifiers
A page from the catalogue of 1964, put to press in February 1964. Note that the units as described (though not depicted) have "two low impedance inputs" and a "master volume". Envisaged use: "For factory, theatre, club, pop groups, etc.".
A detail from the "Precision in Sound" newspaper of 1964. The units pictured above have "three high impedance inputs and one music input" The amplifier below follows the format depicted.
Second generation Metal-Clad amplifiers
To be populated soon (Oct. 2018)