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AC Coupling

AC Coupling (sometimes also known as DC-Blocking) is an electronic engineering arrangement that allows an audio (or any other alternating) signal to be passed through a connection while simultaneously preventing any DC bias or offset voltage on the source signal from getting through. In other words, AC coupling rejects any DC components within a signal, passing only the AC elements. The simplest form of AC coupling is a series capacitor in the signal line and, in effect, it forms a high-pass filter with a very low turnover frequency.

AC coupling is employed widely in audio circuitry to isolate the DC operating condition of one stage of circuitry from affecting the next, and to protect parts of an audio chain from the potentially damaging effects of DC voltages.

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