Fender Style 10KL Bias Balance Pot with Center Tap

[Justa]

I am considering a 5E3x2 build with a quad of 6V6's that I would to have the option of running fixed biased in addition to cathode biased.  To bias the amp in fixed biased mode I would like to be able to balance the sides in addition to having a bias level pot.  I'm not having luck finding a bias balance pot like Fender used, 10KL with a center tap.  Anyone know where I might be able to locate one, Doug doesn't carry them?

Thanks

[sluckey]

Can't help with the tapped pot but I can suggest a much better alternative...

Just build a bias supply with two pots, one for each side.

[Justa]

Wow, thanks Sluckey,
Never would have thought of that.  That should work just fine!

[sluckey]

Here's the dual bias mod I did to my Sunn...

     http://sluckeyamps.com/sunn/sunn_sceptre_1971.pdf

[kagliostro]

I recently posted a possible solution on a TIMBO thread



it uses a standard pot and two resistor to achieve the same result of a center tapped pot

(the faint drawing is part of the circuit)

Franco

[Justa]

Thanks Franco & Sluckey!
I can see now that there is more than one way to skin a cat!

[Alistar]

Sluckey - what's the deal with that "MidBoost" switch on the Sunn schematic - either way, doesn't the signal just ground-out there?
 
Pretty dang cool circuit there, though!

[sluckey]

As shown, the switch enables a local feedback circuit from plate to grid of V3A and also switches in a cathode bypass cap on V3A. Flip to the left and the local feedback loop is disabled and V3A cathode bypass cap is removed ***AND*** a cathode bypass cap is enabled for V1A.