Pin 6 on octal power tubes?

[Steve Conner]

Hi all,

I'm investigating an English beam power tube called the CV4060/S11E12 just now. It has the following pinout:

1 - "Internally connected" - seems to be N/C on the tubes I got
2 - Heater
3 - Plate
4 - Screen
5 - Grid
6 - Beam plates
7 - Heater
8 - Cathode

So it's similar to most octal power tubes except maybe for pins 1 and 6. So my question is, what do other people do with pins 1 and 6 on their power tube sockets? If I ground both pins 1 and 6 on my homebrew amps, will other tubes work? I know the EL34 has its suppressor grid on pin 1, and my goal has always been to get my amps to take any octal tube I can get my hands on

[Enzo]

See if you can eyeball where the pin 1 support wire goes inside the tube. It may be NC, then again it may be welded to a support item that is too close to something else, like a plate support, for safety.

In any case, if you can use the tube with pin 1 grounded, why not.

SOmething useful here maybe: in the RCA tube manual, a 6L6 for example has base arrangement 7AC, 6V6 the same. They don't even have a pin 6 so you are off the hook there at least. But my point was that in the back of the RCA book ther is a chart of base wirings. One chart is tube number versus terminal diagram, but the other is terminal diagram versus tube number. So you can see what all tubes use the 7AC base wiring. 8ET for the EL34.

You can also look over the base pictorials for pentode octals and see how many equate to power tubes.

ALso in the front of the book is an applications guide, which lists power audio tubes, so the hunt might be less work.

Mine - RC28 - has a typo. "6BQ5/EL34"

Here is the wrench in the works: 7027.

A 6L6 will work in a socket wired for 7027, but a 7027 has pins 5,6 wired together for G1 and pins 1,4 wired together for G2.

And 7591 would be all out of sorts.