will be minimized, and the voltage at the input of the amplifier will be close to voltage as if the amplifier circuit was not connected. When a device whose input impedance could cause significant degradation of the signal is used, often a device with a high input impedance and a low output impedance is used to minimize its effects. Voltage follower or impedance-matching transformers are often used for these effects.

The input impedance for high-impedance amplifiers (such as vacuum tubes,