Music in the Round #68

Power amplifiers are unglamorous but essential. In theory, they have only one task. But, according to audio sage Yogi Berra, "in theory, theory and practice are the same. In practice, they are not." Amplifiers must take a voltage input signal and provide an output of somewhat higher voltage but of substantially higher current, the product of which is power. The task is complex in that this output must be applied to electrical interfaces whose characteristics vary widely from speaker to speaker—across the audioband and, for some, even at different power levels. There are no control mechanisms or feedback signals to help. The power amp must just stand and deliver.