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Vintage threads from the first ten years
One or two cathode bias resistors?
 3/4/2000 6:15 AM |
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ADM | One or two cathode bias resistors? I've noticed that most older cathode biased amps use a single bias resistor (ie Fender Deluxe or Vox AC-30), I think I've seen some newer amps (Matchless?) that use individual resistors. Anyone want to comment on the pros and cons of either setup. I would be inclined to separate the cathode resistors because... 1. I remember reading somewhere in a discussion of phase splitters how sharing a cathode resistor helps ensure better balance of the output, ie reducing distortion. So wouldn't sharing a cathode resistor reduce distortion in the output section, which may not be such a good thing if that is what you are after. 2. If you have an AC-30 type amp and split the cathode bias resistors into two push-pull pairs. It would be a simple modification to lift two of the grounds on one resistor for a half power type circuit. 3. The power disipated in the cathode bias would be split over multiple resistors, improving reliability. |
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| D.L. I think its a great idea to have in... -- 3/4/2000 9:53 AM |