" Early models consisted of a hand tuned Swiss musical movement (like a music box) fitted with a magnetic pick up and the amplifiers used radio-type valves. In 1958 reliable transistors came on to the market and efficient amplifiers were built to work directly of the vehicle's battery."
British vans traditionally use 'Grampian Horn' loudspeakers (which cost about £60), pointed down at the road to disperse the sound.
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