Common Power Supply, Feedback Between Stages

[steve]

In this October, 1997 White Paper, I discuss the problems of using a common power supply for all the stages in a component.

In short, musical signal information is fed back from stage to stage(s) through the power supply filtering stages. Another reason why your stereo system does not sound natural/accurate.

Since the power supply capacitors have AC resistance/reactance, the amount of unwanted musical signal fed back is frequency dependent as well. The lower the frequency, the greater the amount of unwanted feedback, with phase shifting.

The best solution, of course, is to use a separate power supply for each stage. However, some designs, such as the phono stages cannot feasibly use separate power supplies for every stage. In such cases, care must be taken when designing the power supply.

Here is the link.

http://www.sasaudiolabs.com/theory8a.htm

Cheers

steve