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Main principles of amplifier wiring

Main principles of amplifier wiring

There may be differences depending on how the amp is fed: whether symmetrically or asymmetrically. These two main concepts are commonly called split supply and single supply, respectively.
With asymmetrical power supply there’s a voltage divider on the (+) input, which sets the operating point of the amp (the bias voltage), i.e. the potential, to which the amp converges without input signal. With symmetrical power supply the operating point is anchored to ground with a single resistor. Furthermore, with asymmetrical supply there’s a big coupling cap on the output, that is not needed with symmetrical supply. This capacitor may limit the frequency response in the bass range. With both types of power supplies there’s a coupling cap in the feedback, with one pin connected to ground – theoretically it shouldn’t be needed with symmetrical supply, but it’s always there in practice. There’s one good reason for this: without this cap, real amps would suffer from their input DC offset, which they would multiply by the preset amplification ratio. With this cap, amps act like voltage followers and transfer the input DC offset with amplification of one.


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