The Williamson amplifier, designed by the British engineer D. T. N. Williamson
was first published in the spring off 1947 in "Wireless World". Williamson
was employed by "The M.O. Valve Company" , one of the manufacturers of
the famous KT66 tetrode.
His amplifier employed a pair of KT66's connected as triodes in a push-pull 'class A' configuration with a maximum output power of aproximately 16 Watts. But what really made this design so special was its very low distortion.
Williamson's amplifier design soon became the benchmark for the many new amplifier designs that sprung up in the early 1950s and although Williamson never sold his amplifier commercially, many small manufacturers produced versions of it. During the early 1950s it was quite common to see the name 'Williamson' being referred to in amplifier descriptions on both sides of the Atlantic.
(Many thanks to Keith Snook,
d.c. ~ daylight ltd. {Wide Spectrum Engineering} for permitting me to
reproduce his retouched graphics for these articles)