TABLE OF CONTENTS This section addresses the special PCB design problems presented by power amplifiers, particularly those operating in Class-B. All power amplifier systems contain the power-amp stages themselves, and usually associated control and protection circuitry; most also contain small-signal audio sections such as balanced input amplifiers, subsonic filters, output meters, and so on.
Other topics that are related to PCB design, such as grounding, safety, reliability, etc., are also dealt with.
The performance of an audio power amplifier depends on many factors, but in all cases the detailed design of the PCB is critical, because of the risk of inductive distortion due to crosstalk between the supply-rails and the signal circuitry; this can very easily be the ultimate limitation on amplifier linearity, and it is hard to over-emphasise its importance. The PCB design will to a great extent define both the distortion and crosstalk performance of the amplifier.
Apart from these performance considerations, the PCB design can have considerable influence on ease of manufacture, ease of testing and repair, and reliability. All of these issues are addressed below.
Successful audio PCB layout requires enough electronic knowledge to fully appreciate the points set out below, so that layout can proceed smoothly and effectively. It is common in many electronic fields for PCB design to be handed over to draughtspersons, who, while very skilled in the use of CAD, have little or no understanding of the details of circuit operation. In some fields this works fine; in power amplifier design...
