I have 2 ARC LS (line stage) pre amps that have some years on them. One is in really good shape, the other needs a lot of love. I plan on NOS tubing and new caps. I'm not posting the schematics, but I have a question on why these 2 units have resistors into the power supply filter capacitors and one has a very small rf coil, which to me bypasses the resistor anyway. They both are similar but not exactly the same. I drew a rough pencil sketch. I have been building tube equipment since the 80s and I've never seen anyone put a resistor to the filter cap, unless is was to series drop the voltage for other stages, which these clearly do not do. It looks like it would simply make the caps less effective. 😕
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These are for damping the resonant circuit of the big caps and their internal stray inductances, likely to keep the regulator from trying to oscillate.
All good fortune,
Chris
All good fortune,
Chris
This is the patented ARC decoupled electrolytic circuit. You left out the essential smaller shunt capacitor.
US5036292A - Decoupled electrolytic capacitor
- Google Patents
US5036292A - Decoupled electrolytic capacitor
- Google Patents
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Thanks! That patent application helped a lot. I see what they are saying, would be interesting to toss on a scope and test it. They are quiet and sound great as is...