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Re: Parafeed line autoformer line output.

Posted by Paul Joppa (P) on December 24, 2001 at 21:03:25

In Reply to: Re: Parafeed line autoformer line output. posted by DrM on December 24, 2001 at 20:39:18:

I have to agree that a choke load provides incomplete power supply isolation. But I do think it's quite a bit. Your circuit with series feed would, I expect, be even more sensitive to power supply capacitors. At least I'll propose that argument.

I am continually amazed at how much isolation from the power supply is needed. Moving to parafeed has an audible effect, which I attribute at least partly to power supply isolation. But current sources have significantly more isolation than chokes, and are quite audible. This is around 60 dB isolation from a power supply that is already adequately quiet by engineering measurements. And I've heard in the last few months the effect of shunt-regulating the power supply before the current source, and it is still quite significant. This is probably at least 100dB better than what measurement says is adequate. And the latest I've heard is a current source to isolate the regulator before another current source. And it's still a clearly audible efffect - we're probably talking 160dB of "excess" isolation now. I have no idea where it will end. As an engineer, this is totally bogus and can't possibly be true. As an audiophile, I hear it and I'll incorporate it whenever I can.

Have a great holiday, everyone!

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