Difference between 12AU7 P and 12AU7 S

Can anyone tell me the difference between 12AU7 P and 12AU7 S? Should you specify one type or the other when you order tubes? I’m lost here, any help would be appreciated.

In over fifty years experience with the 12AU7 types I’ve never heard of a “P” or “S” of this type. A 12AU7A, yes, the “A” designation is a trusted and old one.

I believe he may be referring to the Psvane 12au7 and their 12au7 S Art Series tubes. In my opinion the Art Series sounds much better than the older design which came with my BHK Preamp.

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Thanks, I know what you mean. I’d never noticed anything like this with either guitar amp tubes or stereo tubes. Then I happened to look carefully at my Psvane 12AU7 tubes, and also my Mullards. Not the box the tubes come in, but the paint on the tubes. The Psvanes say 12AU7 S and the Mullards say 12AU7 P. I figured I may have missed something all along that everyone else knew about.

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Like you, that would mystify me. I think I would be even more surprised if it were “12AU7S” or “12AU7P.” With the “S” and “P” separated it seems likely just a current manufacturer’s ID letter as opposed to a different universally accepted tube type or designation.

Those are numbers from PSVANES / APOS. The S identifies gold pins and I assume P might be non gold.


The Psvane 12AU7 S Art series have Gold Pins as do the Apos Ray.

Great, thanks!

Excellent, good to know!

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