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Valve Radio and Audio Repair Handbook by CHAS MILLER

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Chapter 29

Public address and high fidelity amplifiers

The use of microphones and loudspeakers to address public gatherings was pioneered in the early 1920s and rapidly became widespread, especially as more powerful output valves and loudspeakers became available. When nowadays young people talk casually of 160 W amplifiers in motor cars, it is interesting to look at the output powers considered suitable in the valve era, when watts really meant watts and was not a meaningless tag. Around 1930 a book published on the work of wiring cinemas for talking pictures stated that between 3 W and 5 W was perfectly sufficient for medium to large halls, in conjunction with very efficient giant horn loudspeakers. Even then some patrons complained that the ...

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