6p3s vs 6p3s-e 6l6gb replacement.

[gadget73]

generally one bias/balance per channel, or if its PPP you do individual bias and a resistor per-tube. You could do it with those break jacks too but I don't really love things with moving contacts. Just seems like a place for issues to develop at some point. Tube sockets have enough contact points that can get crusty, don't really need more.

 

[Lavane]

Something about trying to bias through the entire current draw of the amp especially on the primary side of the transformer seems sketchy to me. An out of spec preamp tube or rectifier tube could throw the whole thing off (even though not by much). I also like the individual cathode resistor method but then you drive yourself nuts trying to get a happy medium between the tubes. This is ok with new tubes that are well matched but doing this always leads me to individual bias adjustments for each output tube which is what I end up doing with almost all my self biased amps.

I agree, it's a goofy way to do it. The power tubes were closely matched though. All four were within 1% of each other. I just figured 35mv was a good place to set them and called it good. I don't really like a single bias pots for a quad a tubes. There might as well be a fixed resistor for all 4.

 

[prww]

gadget73 With a total of 4 of these jacks (2 each mono bloc) I have never had an issue with them in over 40 years. I understand what you are saying though. Simplicity is reliability. Paul.