Balance and variable bias system at the same time?

[72Blazer]

I have some unmatched 6L6s and 6V6s.  I seem to recall a thread earlier this year that showed a fender type amp with both balance and variable bias systems installed.  I think Sluckey posted it.  I can't locate the thread that showed that if in fact I am recalling this correctly.  Anybody recall this or have a layout for this?

[uki]

Rob Robinette have several examples in his page:

https://robrobinette.com/Generic_Tube_Amp_Mods.htm

[Latole]

You can built bias circuit with 2 bias pots

[sluckey]

I have some unmatched 6L6s and 6V6s.  I seem to recall a thread earlier this year that showed a fender type amp with both balance and variable bias systems installed.  I think Sluckey posted it.  I can't locate the thread that showed that if in fact I am recalling this correctly.  Anybody recall this or have a layout for this?

I was showing how to add a bias adjust pot to a Fender amp that came equipped with a balance pot. See this thread...

     https://el34world.com/Forum/index.php?topic=28618.msg315226#msg315226

But if you're just wanting separate bias pots for each tube I suggest doing something like I did to my Sunn Sceptre. Your resistor values may be different. See this recent thread...

     https://el34world.com/Forum/index.php?topic=28790.msg316882#msg316882

[Latole]

If you are ready to install 2 potentiometers, it is probably better to have two bias potentiometers rather than one bias and one balance.

This is what I do for the amps I build

[72Blazer]

Thanks All for the information-much appreciated.

Vr
J.

[owen]

If you are ready to install 2 potentiometers, it is probably better to have two bias potentiometers rather than one bias and one balance.

This is what I do for the amps I build

I started doing this recently when I got a pile of used tubes.

my exception for one bias and one balance is fixed bias amps with bias-vary tremolo. currently sketching this plan out for my tremolux and princetons.

[HotBluePlates]

... one bias and one balance ...

If you do that system, you turn the balance first to get the tubes even.  Then you turn the bias adjust to set where you want them.

Although some folks have preferences, you're going to adjust 2 pots any way you slice it.

[TonyM]

I used Rob Robinette's layout with two potentiometer on my jcm 800 2204 build but  I had to change the 56k resistor to a 68k resistor to bring the bias within a balanced adjustable range.