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Transients Due to Power Supply

Author: N.H. Crowhurst

Two kind of distortion caused by delayed changes voltage

The effect of a transient on the power supply may result in one type of transient distortion. A sudden burst of audio usually causes the current demand from the high-voltage supply to change, and with it the grid bias for the output stage and possibly the voltage supplied to the screens of any pentode tubes. This change takes time. When the change in audio is suddenly applied to the amplifier (as might happen when amplifying piano notes, for example), all the operating voltages and currents in the tubes are at their condition for minimum audio. When audio arrives at a high level, the amplifier starts to handle it, with the operating voltages and current as a moment before, but the current increases rapidly and the voltages begin to change. This change sometimes alters what happens in the amplifier and can introduce some kind of distortion before the amplifier gets to its new condition. The gain might also be altered in such a way that the quality of the applied transient (the piano note, or whatever it may be) is changed considerably.

Last Update: 2010-11-03