CHAPTER 8
Variable Gain Stages
This chapter deals with amplifier stages that are required to have a variable gain, usually over a wide range of +20 dB, +30 dB, or more. It does not include volume controls, which typically only have a maximum gain of +10 dB or so and have their own chapter (Chapter 13). Nor does it include balanced microphone preamplifiers, which can have a variable gain range of 80 dB or more, and also have their own chapter (Chapter 17).
These amplifier stages are very common in audio electronics. A typical application would be a guitar amplifier input that has to cover a range of playing styles and pickup sensitivities. Another major use is in compact mixers that have only one control performing the functions of both input ...
