The AC30, fitted with alnico magnet-equipped Celestion 'blue' loudspeakers and later Vox's special 'Top Boost' circuitry, and like the AC15 using valves (known in the US as vacuum tubes), helped to produce the sound of the British Invasion, being used by The Beatles, The Rolling Stones, The Kinks and the Yardbirds, among others. In 1959, with sales under pressure from the more powerful Fender Twin, by request from The Shadows, who requested amplifiers with more power, Vox produced what was essentially a double-powered AC15 and named it the AC30. Features simplified from the AC15 included a tremolo effect (mislabeled as 'vibrato'), a single, shared Tone control, and smaller output transformer. Vox released the 12-watt AC10 in late 1959 as a student model, originally as a 1x10-inch combo and later as a 2x10-inch combo. It was popularised by The Shadows and other British rock 'n' roll musicians and became a commercial success. The company was renamed Jennings Musical Industries, or JMI, and in 1958 the 15-watt Vox AC15 amplifier was launched, 'vox' simply being the Latin word for 'voice'.

In 1956, Jennings was shown a prototype guitar amplifier made by Dick Denney, a big band guitarist and workmate from World War II. Jennings's first successful product was the Univox, an early self-powered electronic keyboard similar to the Clavioline. The Jennings Organ Company was founded by Thomas Walter Jennings in Dartford Kent, England after World War II. 1.5 Expansion, Transistors, and Decline.

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