Post by SheaNC Could someone please tell me the difference between 12AU7 and 12AU7A tubes? Thanks very much!
The difference is insignificant. I think the "A" tube has a spiral filament to reduce noise. But this is such a low gain tube, noise shouldn't be an issue to begin with. Substitute one for the other freely.
Post by SheaNC Could someone please tell me the difference between 12AU7 and 12AU7A tubes? Thanks very much!
According to the 2-56 G.E. datasheet, the electrical characteristics of the 12AU7A and 12AU7 are "essentially iequivalent." The difference is, compared to the 12AU7, the 12AU7A "exhibits a lower microphonic output."