Whats the point of this?

[Gtr_tech]

I'm working on a PV "Vintage" right now. It has an odd screen resistor setup.....2 tubes are direct connected to the screen node, and the other 2 are connected via 100 ohm resistors. Eh? I don't see the point here. Why limit screen current on 2 tubes only?

Output section looks just like the "Deuce" shown here:

http://www.webphix.com/schematic%20h...vy_deuce-b.pdf

Most other PV 6L6 output sections use seperate 100 ohm'ers on each screen.

[madkatb]

Yesterday's question.
http://music-electronics-forum.com/t27899/

[Enzo]

Not there to limit screen current on the two tubes. The resistor serves to isolate the two tubes so the screens don;t interact. PV did this on numerous models.

[clyde1]

What would that interaction be Enzo?

[Enzo]

One of the tube mavens could probably answer better. This is not my area of expertise.

Screens can affect gain of the tube, so if the screen on one tube draws more current for some reason, it would change the voltage on the other in a pair.

[Gtr_tech]

At any rate....I don't like it. It'll get seperate 470r on each screen as to not stress the screens of new prod. glass.