Please, give me your opinion on elevated DC heater wiring

What would you use?




or



Thanks!

rafafredd, are we to assume that the cathodes are at about 0 volts relative to the +115?

cathodes are at +160 volts relative to ground. So, I have to bias the heater up to +115V. So cathode should be aprox 45v above heater.
What I want to know is what do you think is better for using as the +115v reference point in the heater PSU.

Should I leave all pin 9 on the tubes unconnected and use the +12v return as a 115v reference (as n the 1st drawing), OR should I use Pin 9 at one of the tubes as the reference point instead (as in the 2nd drawing)?

Sorry for the bad representation of heaters. I couldn´t find a better way unfortunetly. Anyway, each arrow is a set of heaters in a 12au7 tube, with two heaters and three pins (4,9,5). I hope it´s understandable.

Thanks!

I don't see that it makes a bit of difference, except that bringing a 3rd wire back to the power supply adds labor.

Yeah, I can't see where center-tapping the reference would make any real difference here. If it were a direct heated tube there are the issues about the varying potential along the filament, but I don't think those tubes ever have center-tapped filaments (?).

I thought maybe you were doing something by way of reverse-biasing the filament with respect to the cathode. This is done sometimes to counteract filament-to-cathode current flow, which can get noticeable if cathode material gets on the filament. It's mentioned somewhere in the RDH.

Thanks guys. If it makes no diference, I´ll go with number one.

:guinness: