series heaters for 12ax7 preamp 24vac

[stevesamps]

somehow I just cant picture how to wire this?
I had this idea to use some surplus transformers
for small preamp things with 2x 12ax7

Does this make sense to do ?

run the 12V heaters in series to use the 24v winding
so pins 4 and 5 only right?

I am used to wiring them up for 6.3volts

and then I had working a doubler/tripler scheme for the
other winding..

not saving a whole lot of coin I know but
I have like 10 of these things..

Steve

[Bruce / Mission Amps]

Originally Posted by stevesamps

somehow I just cant picture how to wire this?
I had this idea to use some surplus transformers
for small preamp things with 2x 12ax7

Does this make sense to do ?

run the 12V heaters in series to use the 24v winding
so pins 4 and 5 only right?

I am used to wiring them up for 6.3volts

and then I had working a doubler/tripler scheme for the
other winding..

not saving a whole lot of coin I know but
I have like 10 of these things..

Steve

You mean you want to wire them up like this?......

[stevesamps]

Originally Posted by Bruce / Mission Amps

You mean you want to wire them up like this?......

I think I will give it a go...

[Don Moose]

One noise-reduction suggestion - you should probably ground one of the 24VAC leads and wire the tube with the earliest triodes to the grounded side.

(did that makes sense?)

[stevesamps]

you mean the first and second stage if I cascade them?

I imagine I could also do a false centertap and ground that?

then again this "aint" 6.3v any more..

Steve

[Don Moose]

A false CT good for 150mA? I dunno. (by which I mean that I do not know, not that I'm dubious of the idea)

First and second stages, yes, that's what I meant.

Hope this helps!

[Gregg]

Check out Peavey Classis 50 schematic. The preamp tubes there are wired this way.