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I built a new PSU for my Apheared 47 amp based on 7815/7915 fixed voltage regulators.

Surprisingly, I got a high frequency hiss in both channels. Till now I have used 1983 made Power-One regulated dual PSU (complicated schematics based on LM723 regulators) without any hiss problems.

The amp and the PSU circuits are soldered on one protoboard. I saw some PSU projects at Headwize with added 10 ohms resistors in series with voltage pins to reduce the high frequency junk. The PSU ground path is a wire from the transformer to the amp’s star ground.

Does anybody could give me an idea what is the source of my problem? Maybe the 78xx/79xx tend to oscillate or the PSU circuit makes the opamps to oscillate? Maybe I should go for LM317/LM337 with better ripple rejection? Or I just made a mistake or ground mishmash? Please help me.