Valve amplifier, a Mullard 5-20 Watt design adaptation with original Mullard EL34 valves, by Shirley Laboratories Ltd, Worthing,1954-1960

This is an example of a mono valve amplifier featuring original EL34 valves, built to a version of Mullard’s 5-20 Watt design that dates to the early 1950s. It was made by a small business, Shirley Laboratories Ltd., and is one of their earlier valve amplifiers.

Shirley Laboratories was formed in 1954 by Arthur W. Wayne, a professional engineer, musician (he was a famous concert pianist), broadcasting star, and contributor to popular electronics publication "Wireless World." Before setting up Shirley Laboratories, Wayne worked as a consultant in the field of acoustics. He used his expertise in engineering, music and acoustics to build high-quality sound-reproduction electronic equipment, in particular amplifiers, radio tuners and electronic instruments. The company ceased operation in the early 1970s.

Valve amplifiers use vacuum tubes to increase the amplitude or power of a signal and were used to amplify electrical signals, first in telephony and military telecommunications during the First World War and later in telephony and wireless communications more generally in the 1920s onwards and in domestic radio receivers in the 1930s onwards. By the 1940s, valve amplifiers were being used for more general audio amplification and this increased in popularity after the Second World War as the electronics industry in Britain and elsewhere adapted to the post-war commercial marketplace.

For post-WW2 audio amplification, valve amplifiers were often used as part of larger domestic ‘high fidelity’ or ‘Hi-Fi’ audio systems, which were produced and marketed as whole systems, but were also largely put together by ‘DIY’ hobbyists with details published in various popular magazines such as “Wireless World” (which Wayne contributed to) and to a growing DIY community. Hobbyists could experiment with hi-fi design combinations to produce a sound and tone of their choice on a budget and many small businesses popped up to feed this market - including Shirley Laboratories.

Valve amplifiers were at peak popularity during the 1960s, but this declined in the 1970s as the silicon transistor grew in popularity. Small-scale production companies like Shirley Laboratories could not compete with the growth of mass-production at this time - only a handful of valve amplifier companies obtained long-term success, such as Leak & Quad. Whilst this technology is largely obsolete today, there is still a keen community of fans and DIY/hobbyists.