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Re: feedback on b+of circlotron

Posted by Lew (A) on September 7, 2006 at 13:15:26

In Reply to: Re: feedback on b+of circlotron posted by TUBEVIBB on September 7, 2006 at 10:32:52:

I think you are talking about the 1K ohm resistor that Ralph shows going across the two banks of caps that filter the LV supply (that is, the +/-140V supply for the output tubes). I built my amps from a schematic supplied by Ralph, and I therefore dutifully also installed that resistor, using a 5W or 12W Mills. There is no voltage across that R because both halves are at the same potential, so really a high-wattage resistor is/was not necessary. I never thought about it as a "feedback" element in the circuit. I think Ralph once told me that he was ambivalent about the necessity for it, but I left it in my highly modified MA240 amps.

That said, I am not sure what you need "help" with. You seem to have done fine by yourself. If you want reassurance, OK, you got it. Your observation that the 1K ohm resistor makes an important sonic difference is very interesting; never experimented with it myself. I always assumed that the 1K resistor was used in all Atma factory-built products, but I would not know for a certainty.

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