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Vintage threads from the first ten years
| previous: Doc This amp uses negative feedback fro... -- 4/12/1999 12:44 PM |  |
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Re: Screeching preamp in DIY amp(s)
 4/12/1999 12:54 PM |
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Aaron | Re: Screeching preamp in DIY amp(s) Hmmm, I don't think that's it. Yeah, it uses neg fbk from the OPT. When I built the power amp, I found that I did in fact have the feedback phase reversed, and corrected it. I'm pretty sure the problem is contained in the preamp. As I said, I have a separate gain and master. So long as I have the gain at 3 or less, I can crank the master to kingdom come and it sounds fantastic. I just can't go above 3 on the preamp gain! Because of my experience with this problem in other amps (my 2203, plus a 200v 2x12AX7 preamp I am working on), I think it has something to do with the signal amplitude relative to the cathode bias level of the following preamp stage. I just can't figure out exactly why, though, since the preamp is very close to the plexi preamp and should not be acting this way... Any other ideas??? Thanks... |
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| Dave James Aaron, |