Self on Audio, 3rd Edition

Chapter 26Distortion in power amplifiers

Part V: output stages (Electronics World, December 1993)

This article carried on the investigation into amplifier output stages begun in the previous one.

In the first section of the article, there is the suggestion that the linearity of the VAS can be effectively eliminated by cascoding. With the wisdom of hindsight, ‘eliminated’ was probably a bit optimistic. Later experience has convinced me that adding an emitter-follower within the VAS Miller dominant-pole loop is a more effective and dependable way of implementing this linearisation; no components are required for biasing a cascode transistor, and less voltage is lost on negative swings. I have used the emitter-follower method in all my recent commercial ...