In fact, the progression of rock music as a whole was enabled by production of the valve amp, and Edwards, now part of the Atlas Copco Group, was already involved in producing valves in the 1930s. Valves, or vacuum tubes, were by far the dominant active electronic component in most instrument amplifier applications until the 1970s, when solid-state semiconductors (transistors) started taking over.
Jimi Hendrix loved the depth and warmth that transistor-based amps couldn’t deliver. In fact, nothing screams audiophile authority like a valve (or tube) amp, and even today there is a niche of purists who continue to specialize in building them.
