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Vintage threads from the first ten years
Immediate Feedback at Startup
 8/20/1999 1:33 PM |
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Mook | Immediate Feedback at Startup This applies to my homebrew (2xEL84) fixed bias. When I turn on the amp, after rectifier and heater warmup, It starts to feedback wildly.... I checked R.G.'s Debugging page and tried the 2 most suspect items: 1) input jack - I pulled the 1st preamp tube and the feedback remained, so I can rule out the jack. 2) bias supply diode or cap - well, I'm getting a consistant and steady negitive bias, so I'm assuming the bias supply is working properly...... Any ideas what would cause a very low pitched feedback? I'm going to pull the rest of the pre-amp tubes tonight in hopes to try and isolate the feeback to a particular section. Mook |
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| Replies: |
| R.G. Very low pitched oscillation, right... -- 8/20/1999 3:07 PM R.G. Wait a minute - is this the same am... -- 8/20/1999 3:08 PM Doc Is this a push-pull amp with a nega... -- 8/20/1999 3:37 PM Bruce I would hope your PT is OK since th... -- 8/20/1999 4:47 PM |