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Old 15th June 2007, 11:57 PM   #41
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Join Date: May 2006
Location: Berlin
I'll take a look. Is there any chance that the negative feedback could be fed through TWO small capacitors in series? that way the caps could block DC, and the AC signal would be twice-inverted and not make positive feedback..?
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Old 16th June 2007, 12:09 AM   #42
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No, you'd only need one cap in series with the feedback resistor to block DC. Caps don't invert signals, but at very low frequencies series coupling caps do introduce phase shift. This is workable though.
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Old 16th June 2007, 12:14 AM   #43
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If you say so. I don't remember tenth grade physics that well... Anyway what size capacitor are we talking here? I've got a few cheap .22uF caps I could use, but I don't want to solder the bulky pots in there again. is 47K in series with .22uF a good start for feedback? I'm still using 7AU7's.

p.s. the amp sounds pretty good, very solid imaging and very little hum. i'm happy
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