name that tube

"Goodbye 45 tube"??? Give me a break.

A 10-watt tube in SE class A has . . . what, 250-300v on the plate at 35-30mA? So changing the B+ by 35v will change the plate dissapation on the output tube by about 1-1/2 watts . . . differences in transconductance across various 45s will cause at least this much varation.

Not to mention a variation in line voltage by 10% . . . again, the differences AREN'T huge. But I guess if you own/build an amplifier that runs all the components really close to the bleeding edge, then maybe EVERY tube should be hand-picked and measured first.

>>No, but 5V4s and 5Y3s are basically interchangable<<

No, they are not.

For example, 5Y3 is a popular rectifier for 2A3 amps and 5V4 for 45 amps.

Now, using your assertion, stick that 5Y3 into the 45 amp and watch the snap, crackle, pop action of your triodes.

Very bad information.

Audiofeil,

I know you know much more about tubes than I do, but I'd always read (or at least thought I had) that you could use a 5Y3 with either a 2a3 or 45, and that it is the 5v4 that should not be used with a 45 triode.

Am I mistaken?

Try putting the tube in the freezer for a while, sometimes the markings that have been wiped off will show up in the frost.

Sorry, Darosenb my post is in error. The idea was correct but the typing was not.

An amplifier manufacturer I represent vigorously cautions against using the 5V4 with a 45 as you point out.

The 5Y3 is appropriate for the 45 Triode and could work with the 2A3 in many circumstances.

My bad.

Don't try this at home.