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Biasing 7581A

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  • Biasing 7581A

    I just finished up a JTM45 with a bunch of spare parts and I'm using a PT which puts out some hefty voltage; it's up to about 490 on the plates when the wall AC gets up to 124-125. Anyway, I've got a bunch of these old Phillips 7581A and I think they're good candidates for this. I just got it all up and running and have the bias adjusted, but currently I'm biasing them as per 6L6GC which are 30W tubes. However, *supposedly* 7581A are 35W tubes so I ought to be able to heat them up a bit more should the sound warrant it; I'm not sure, though, if this is accurate or just urban legend. Anyone with any experience using these - are you biasing them like 6L6GC or like 35W tubes? Thanks!

  • #2
    You can go hotter,just watch your plates and be sure the dont redplate.

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