Why are screen resistors soldered right at the G2 pin?

[overtone]

I understand why G1 grid resistors are mounted as close as possible to the G1 pin on the socket, but why are the screen resistors also mounted direct - at the G2 pin?
It has been that way on all amps that I have seen.
Would it be very naughty to have them on the board?

[mooreamps]

I understand why G1 grid resistors are mounted as close as possible to the G1 pin on the socket, but why are the screen resistors also mounted direct - at the G2 pin?
It has been that way on all amps that I have seen.
Would it be very naughty to have them on the board?

Not too naughty. Better to have one on the card, verses none at all.. But given the "black magic" of the thing, they do work the best when mounted directly on the tube socket, if possible....

-g

[pdf64]

My (sketchy) understanding is that the screen grid resistor also acts as a grid stopper, as well as a current limiter, on the screen grid. So there may be a beneficial effect in mitigating for oscillation, by mounting it on the tube socket. Need to read RDH! Pete.

[kg]

pete's got it.

stoppers need to be placed as close to the amplifying device as possible. this will limit the stray reactance on the connection node (both inductive and capacitive) and improve stability.

[loudthud]

The kinds of parasitic oscillations that stoppers (G1 or G2) quell can be almost impossible to track down and fix if you don't have an oscilloscope. They may come and go if you move a wire or change tubes or even change the bias. Thankfully, most tubes used in audio are not overly sensitive to this but plug in some re-pinned Soviet tube and who knows? The chances that you will get away with being naughty are pretty good. Just remember that even flame proof resistors can get hot enough to damage boards and adjacent components. Mount them up off the board and not too close together.

[overtone]

Thank you for the replies. I had not understood that the g2 resistor will also act as a stopper. Even though I have probably read that a few times...
So I will stay with mounting at the g2 pin, it's like something for nothing and a bit of point to point frees up space on the board too.