What are the major difference between power amplifier and voltage amplifier?
closed as too broad by Olin Lathrop, Finbarr, Andy aka, Bimpelrekkie, winny Jun 5 '18 at 7:25
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A voltage amplifier takes a small voltage signal, say in the millivolt range, and outputs a similar signal that is scaled by some multiple (the gain) of the original signal. This gain can be > 1, = 1 (buffer), or < 1.
A power amplifier, in the context of practical electronics, uses a small incoming signal (typically voltage or current) to control a large amount of power (volts x amps). "Large" is relative to the input signal; the power amplification stage of a guitar amp might only handle a few watts, while a generator voltage regulator's power stage might handle hundreds or thousands of watts.
Designers don't conceptually consider a power amplifier as a device that uses a small power input to control a large power output. As stated above, you'd input a voltage or current.