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partial feedback
after numerous problems i am knocking partial feedback on the head
here's the articles that can explain the theory much better than me: http://www.tubecad.com/march2001/ and olsher's t rex: http://www.enjoythemusic.com/magazin.../0105/trex.htm for some reason i keep getting a voltage on the 300b grid it is a gradually increasing phenomenon getting up to over 150V and popping the cathode bypass cap there is a distortion which increases with time presumably as the voltage on the grid rises takes a few weeks i thought at first it was the 2uf cap in a short loop.. 300b anode to grid -as i'd done it the t.rex way- but i've tried with different caps and now i've now tried a 100K feedback resistor to driver anode and the same happens on one occasion i could follow the measured voltages when switching 300bs which suggest a valve problem but when i remove feedback the problem is gone i don't know why this is i can post some thoughts though: the valves are faulty but why only when feeback applied? is it because of the aikido driver configuration? or the resultant low driver output impedence? whatever i've got all these half realised half understood ideas about this but it doesn't work in this house |
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