Audio amplifier power supply design


Posted on Feb 4, 2014

Advantages and disadvantages of different power supply technologies as well as the design considerations involved in choosing and evaluating a mains transformer. The pros and cons of external supplies, inrush current control, RF emissions from bridge rectifiers, and relay supplies. The literature on power amplifiers frequently discusses the


Audio amplifier power supply design
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importance of power-supply rejection in audio amplifiers, particularly in reference to its possible effects on distortion [4]! I have (I hope) shown in earlier chapters that regulated power supplies are just not necessary for an exemplary THD performance. I want to confirm this by examining just how supply-rail disturbances insinuate themselves into an amplifier output, and the ways in which this rail injection can be effectively eliminated. My aim is not just the production of hum-free amplifiers, but also to show that there is nothing inherently mysterious in power-supply effects, no matter what subjectivists may say on the subject. A proportion of the 100 Hz ripple on the rails will appear at the output, degrading the noise/ hum performance. Most people find this much more disturbing than the equivalent amount of distortion. The rails also carry a signal-related component, due to their finite impedance. In a Class-B amplifier this will be in the form of half-wave pulses, as the output current is drawn from the two supply rails alternately; if this enters the signal path it will degrade the THD seriously. The second possibility, the intrusion of distortion by supply-rail injection, can be eliminated in practice, at least in the conventional amplifier architecture so far examined. The most common defect seems to be misconnected rail bypass capacitors, which add copious ripple and distortion into the signal if their return...




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