paralleling 2 power transformers?

[Jim R.]

I forget now where I read about this, probably somebody in the NYC triode club in the early days of the SET renaissance, but there was a competition and one of the entrants used two equal power transformers in parallel (lowering the overall impedance of the power supply) and handily walked with best sound honors.

Can this be done with reasonable safety with the pt2?  Maybe even series wiring the 2.5 v secondaries so there will be enough voltage overhead for a 2.5v DC filament supply?  Of course phasing would be extra important here, but other than that, what are the ramifications?

Thanks,

Jim

[Paul Joppa]

It's always problematical to parallel voltage sources, just as it is difficult to put current sources in series. For voltage sources in parallel, very slight differences in actual voltage or internal resistance will result in much larger differences in current.

I seriously question whether the reduced resistance actually had much to do with taking the best sound award. Not that I've heard it, so just my humble opinion at this point. With shunt regulation following the power supply, it should be even less important - again, I can't back that up with experience.

[Jim R.]

Paul,

Pretty much as I figured, but was wondering if there was something I was missing.

I did remember who did this, but still can't find where I read it.  It was Larry Moore. other than that I don't remember who the others were or any of the other circumstances.

I'm definitely leaving this alone ;-).

-- Jim