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feedback and/or oscillating tube preamp

208.254.124.39

Posted by e-mail on August 14, 1999 at 04:29:51

Might a generous one among you help with this? Although I'm now using my trusted and true Foreplay form ET, I am just plain stumped with a problem I have in a preamp I built this summer from an old Bruce Rozenblit schematic (once in Glass Audio in the very early 90s). The unit begins to produce a background, high pitched feedback or whistling and chirping sort of distortion after it has warmerd up after a couple of hours. I have changed tubes numerous times; have switched cables; experimented with grounding options -- and just can't fix the situation. I did add a couple of resistors on the volume pot in series to help knock the gain-level down a bit for very efficient Lowther drivers, but this was the only mod to the original design. I don't know what else to do...

Begging some assistance when convenient...

erik mandaville

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