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Old 5th July 2004, 04:22 PM   #1
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Default #26 line stage help

Ok I have finally gotten around to playing with the #26 again. I have B+ of 306V, plate resistor value of 43K, plate voltage of 133v. I have 10.0v across my 2.5K cathode resistor. I have a cathode by pass of 1000mfd. I am using a 2.0V 5AH battery with a .47 dropping resistor to end with 1.5V. If I understand the tech sheet correctly I should be ballpark and it should be ok.

The main problem still seems to be some small hum that seems to lower in level when I touch the chassis. Any thoughts on how to totally kick the hum to the curb? Now, I have read about every article I could find on the 26 and the hum problems and I thought the hum might go away using the battery for the heater feed. Any thoughts/comments? Thanks for the help in advance.

Joe
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Old 6th July 2004, 11:48 PM   #2
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Anyone?
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Old 7th July 2004, 12:46 AM   #3
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Sounds like ground loop hum. Does it hum with no source connected? Have you tried running a ground wire between preamp chassis and amp chassis?
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Old 7th July 2004, 10:46 AM   #4
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Thank you for your reply. I will try grounding the line stage to the amp tonight and see if it makes a difference in the hum. I will also try it without an input and with the input shorted.

Joe
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Old 9th July 2004, 10:56 AM   #5
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I tried it and it didn't help.
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