80% is excellent, assuming all the values are correct. I wouldn't change it. Don't arbitrarily change stuff without good reason.
Thanks,
Josh
1974x PT replacement
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Re: 1974x PT replacement
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foreverstrung
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Re: 1974x PT replacement
Ya, I'm not going to change anything. Numbers are correct. I triple checked. Put the amp back together 100% and put it thru the motions for about an hour. Sounds fantastic. appreciate all the help
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geoff 1965
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Re: 1974x PT replacement
Well done! glad you are happy with it,I was surprised at the quite low 318 plate voltage and it looks like Marshall aimed at breakup with this design,the stock 91R bias resistor would drop the plate & cathode voltage even more!
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77Custom
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Re: 1974x PT replacement
Foreverstrung!! Thanks for the idea to contact Marshall about the bad transformer. Mine went out on my 2005 1974x and I contacted them and they are sending me a new on which should be here in a couple of days!!
Glad you got yours going again!!
Glad you got yours going again!!
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