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Marshall JMP 50 watt bias

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  • #16
    You should read my earlier findings ...a few threads up ...The high voltage winding is a whopping 70 ohms!!! and a mere 495VAC!

    I can't up the current...because as you draw more than 150 mills the B+ falls 15-20%...because it is so wimpy. That's how this whole thing got started, I looked at the 400VA power transformer and said..."Cripes" this thing should do 100 watts!!!
    and not even sag 3%.

    That 70 ohm HV coil is about the same resistance as the 5U4 plate resistance. Believe me that 70 ohm coil with diodes acts just about the same as a 5U4 on a regular 15 ohm HV coil.

    I should put a three pole two position switch on the back...."120 volt Primary"...use 6V6's or "110 volt primary" use EL34's.

    Ok enough...I gotta get some work done...

    Mr.Coil

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