Quote:
Originally Posted by The Radium King
you could. the problem is that these are 'dual triode' tubes, so a 12ax7 has two separate gain stages, as does a 12au7. the bassman ri uses one tube to provide one triode as a gain stage and one triode as the cathode follower. if you replaced the 12ax7 in that position with a 12au7 you would get the 12au7 cathode follower, but also a 12au7 gain stage, which doesn't have the amplification of the original triode and you wouldn't be driving the cathode follower very hard. that's why, if you look around, you'll find old tubes that are dual triode with 1/2 as a 12ax7 and 1/2 as a 12au7, where the 12au7 is used as a buffer for the 12ax7 gain stage. not common in current guitar amps, however.
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so if I understand right, the tube position I'm looking at putting the 12AU7 into pulls double duty, and while half of those duties would be served fine by the 12AU7, the other half wouldn't be, because the AU7 doesn't have enough gain. Is that about right?
But I thought you said in your previous post that the 12AU7 works great as a cathode buffer in marshall/bassman style amps? The Bassman RI is a pretty good bassman style amp, right?