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Power Amplifiers for Music Reproduction
The classical concept of the measurement of amplifiers with continuous sine-wave signals does not apply rigorously to amplifiers designed for the high-fidelity reproduction of music. Usually the designer must choose between providing either maximum instantaneous short-time output or maximum continuous sine-wave output; since the usual musical waveform is complex, having peaks 10 or more db higher than the average level, it is obvious that the former condition is best for the reproduction of music. With higher-powered amplifiers, the maximum available continuous power can actually burn out the loudspeaker on a continuous overload. A -snubber- circuit has been developed that does not affect the power-handling capacity of the amplifier on music waveforms but which protects the loudspeaker from continuous high power levels. By this means, high-powered amplifiers can provide maximum realism on peak music levels without the usual danger of speaker burnout. Such a device can be adjusted by the user to provide any degree of -snubbing- action. An important consideration with respect to amplifiers, much misunderstood, is the internal output impedance or damping factor. Many amplifiers have output impedances approaching zero, while actually most loudspeaker manufacturers recommend a finite source impedance of a magnitude which may be as high as the rated speaker impedance. A system is described which, while providing adjustable output impedance without adversely affecting amplifier performance, allows optimum damping for all types of loudspeakers.
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