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worldoftone

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  1. Nope. Welcome to amp maker misinformation. - WOT
  2. Postscript: I usually bias amps as cold as possible while still trying to retain the best tone. Hotter does not always mean better. New production tubes - well, from what I have seen they aren't as stout as the old ones - so take the "70% of max plate dissipation" with a grain of salt. - WOT
  3. Take the bias rite. Get mA reading. Take ohm meter. Measure plate voltage on power tube (connect positive end to pin #3, neg end to ground). (Some bias-Rites have the plate voltage switch - use that if you have that version) Multiply pV x mA. That will give you IPD of tube. EXAMPLE: mA = 32 pV = 495 Multiply 495 X .032 = 15.84 watts of plate dissapation. EL-34 MAX plate dissapation is 25 watts. Being that this is a fixed bias amp, you want to run this tube at 70% of plate dissapation = 17.5 watts MAX. So, 15.84 watts of IPD per tube is acceptable. You want to bias to the tube pulling the most current. Last time I biased a Shiva, it sounded real good at around 14 watts of plate dissipation. Use your ears and use the math and you will be OK. - WOT
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