TABLE OF CONTENTS There are three principal ways to power an amplifier:
a simple unregulated power supply consisting of transformer, rectifiers, and reservoir capacitors;
a linear regulated power supply;
a switch-mode power supply.
It is immediately obvious that the first and simplest option will be the most cost-effective, but at a first glance it seems likely to compromise noise and ripple performance, and possibly interchannel crosstalk. It is therefore worthwhile to examine the pros and cons of each technology in a little more detail.
Simple, reliable, and cheap. (Relatively speaking the traditional copper and iron mains transformer will probably be the most expensive component in the amplifier.)
No possibility of instability or HF interference from switching frequencies.
The amplifier can deliver higher power on transient peaks, which is just what is required.
Significant ripple is present on the DC output and the PSRR of the amplifier will need careful attention.
The mains transformer will be relatively heavy and bulky.
Transformer primary tappings must be changed for different countries and mains voltages.
The absence of switch-mode technology does not mean total silence as regards RF emissions. The bridge rectifier will generate bursts of RF at a 100 Hz repetition rate as the diodes turn off. This worsens with increasing current drawn.
Can be designed so that virtually no ripple is present on the DC output (in other words the ripple is below the white noise the regulator generates) allowing...
