Basic Audio is a free introductory textbook to the basics of audio physics and electronics. See the editorial for more information....

Drive Transformers

Author: N.H. Crowhurst

A step-down drive transformer minimizes waveform distortion produced by grid current

Step-down transformers can also be used in the drive stage that feeds a push-pull output stage, where the grids of the output tubes are driven into the positive voltage region during part of the audio waveform. This means there will be current peaks which tend to distort the audio voltage at the grid, caused by a drop in the high source resistance (usually the plate .resistance of the preceding stage). The apparent source resistance can be reduced down by a step-down drive transformer, which thus minimizes the waveform distortion produced by the grid current.

Last Update: 2010-11-03