combine stereo channel filaments ?

dobias · 7th July 2011, 02:09 PM

I know the 2A3's in a stereo SET must have independent filament power supplies, but I don't remember seeing any rules against running the preamp & driver tubes of both channels off of a single filament power source (when either AC or DC).
Is this practical or a no-no?

simon7000 · 7th July 2011, 03:33 PM

If the filament is the cathode then the tube requires separate power supplies. If it has an indirectly heated cathode it is not much of an issue.

dobias · 7th July 2011, 03:39 PM

These preamp & driver tubes are 6SN7/7N7 indirect heated cathodes.
Will combining the left & right channels cause any problems of any magnitude?
Combining the heater supplies will simplify the wiring for me from a separate PS.
Thanks for the response.

simon7000 · 7th July 2011, 04:08 PM

you can combine those

dobias · 05:02 PM

That's great news!
I'm in the throes of simplifying the wiring of my stereo amp that wound up with a rat's nest of wiring because I included two 2.5v transformers & two 6.3v transformers & rectifiers in the undersized amp chassis. Now I'll modify the separate PS chassis for the filaments supply using the 6.3v/3A PT winding for all 4 preamp/ driver tubes.
Thanks again.

7th July 2011, 02:09 PM	#1
dobias diyAudio Member Join Date: Jun 2007	combine stereo channel filaments ? I know the 2A3's in a stereo SET must have independent filament power supplies, but I don't remember seeing any rules against running the preamp & driver tubes of both channels off of a single filament power source (when either AC or DC). Is this practical or a no-no?

7th July 2011, 05:00 PM	#5
dobias diyAudio Member Join Date: Jun 2007	That's great news! I'm in the throes of simplifying the wiring of my stereo amp that wound up with a rat's nest of wiring because I included two 2.5v transformers & two 6.3v transformers & rectifiers in the undersized amp chassis. Now I'll modify the separate PS chassis for the filaments supply using the 6.3v/3A PT winding for all 4 preamp/ driver tubes. Thanks again. Last edited by dobias; 7th July 2011 at 05:02 PM. Reason: change 8 to 3A

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7th July 2011, 03:33 PM	#2
simon7000 diyAudio Member Join Date: Nov 2008 Location: Oakmont PA	If the filament is the cathode then the tube requires separate power supplies. If it has an indirectly heated cathode it is not much of an issue.

7th July 2011, 03:39 PM	#3
dobias diyAudio Member Join Date: Jun 2007	These preamp & driver tubes are 6SN7/7N7 indirect heated cathodes. Will combining the left & right channels cause any problems of any magnitude? Combining the heater supplies will simplify the wiring for me from a separate PS. Thanks for the response.

7th July 2011, 04:08 PM	#4
simon7000 diyAudio Member Join Date: Nov 2008 Location: Oakmont PA	you can combine those

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