Brownface PT question

[alange5]

I'd like to build something based on some of the Fender brown circuits - a cross between the 6G11 Vibrolux and the 6G5 Pro.


I'd like to incorporate the bias-vary tremolo of the 6G11 with the diode rectification and higher voltages of the 6G5.


The 6G5 calls for about 450V on the 5881 plates.  I have two PT options in mind:


Classictone 40-18005
http://www.classictone.net/40-18005.pdf
330-0-330 @ 240ma w/ 50V bias


Classictone 40-18041
http://www.classictone.net/40-18041.pdf
325-0-325 @ 180ma w/ 50V bias and 5v windings




If I opt for the 325V PT, will I be ok with the 180ma current (2x6L6 or 2x5881), and could I simply tie off the unused 5v windings?

[sluckey]

yes, yes

[alange5]

Thanks.


Here's the schematic I'll be working with:





Any glaring problems?  Does the coupling before the PI look ok? (plate > 100k > .05 > grid)

[sluckey]

Any glaring problems?  Does the coupling before the PI look ok? (plate > 100k > .05 > grid)

Each preamp triode needs a 1.5K||25µF between the cathode and ground. Also, connect the .05µF coupling cap directly to the plate of the second preamp triode and remove the 6.8K, connecting point A directly to the 100K.

[alange5]

Thanks for the reply.


Here's the updated schematic with the "A" version of the tone stack (used in both the 6G11-A and the 6G5-A):






I have an extra cutout for a pot on my chassis.  I'm considering adding a master volume.  If I use the "type 2" master volume where a dual gang pot replaces the power tube grid leak resistors, will the tremolo still work properly?


Here's the Robinette example from a 5F6A:

[sluckey]

Trem should work with that MV. Before you commit to that tonestack you may want to find a source for that odd treble pot. Hoffman used to carry it, but not now.

[alange5]

Thanks for the help sluckey.


Looks like amprepairparts.com carries those tapped pots.  They have a whole section dedicated to "brown" parts. 

[sluckey]

Thanks for the link.