National 12AX7A tubes

[finnman]

Has anybody ever heard of National?
I like to trade these to my Amp tech for service.
but don't know the value. I got 30 of them.
They were old stock from work that they were getting rid of.

[fett]

I have a bunch of National tubes. The tubes you have are cool. A halo getter and big plates. Think Telefunken. $20 a pop. Your tech will think less, but figure $350 in service for the tubes.

[finnman]

Thanks Fett,
What type amps would benefit with these?
Old Fender, Marshalls?
I never used a Telefunken tube before.
Are they good for clean amps or others?
Thanks

[fett]

I was more referring to the plate size. It would be difficuit to say whether these actually sound like Telefunkens without testing them in an amp. There are so many variables to consider. Are they prone to microphonics? How do they read on a tester? You really need to try 5 or 6 in an amp to know for sure how good they are. I'll bet you they will sound good.