Mads Barnkob

Electrician, programmer, experimenter and amateur scientist with experience in industry automation, programming and all kinds of high voltage generating electronics. Administrator of and the high voltage community forum

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2 thoughts on “100 Watt output from 6P45S tube amplifier

  1. Looking at your schematics, I see that you are using transistors to bias the tubes. This really is not necessary as the tubes will self bias when putting a 1M resistor from the grid to ground and the cathode to ground through a resistor 1k to 3k. Then the stages will be self biased class A amplifiers.
    My experience is working with tubes as a hobby for about 4 decades, and a MS in electronics. Tubes are not critical in bias as transistors are. Also the tube equipment is great to use during the winter as they are great room heaters. I have a 535 scope and many other kinds of equipment as well.

  2. Hi Paul

    It is not just bias, but balance the transistors is there for. Read the explanation in the start of the article.

    Kind regards

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