Depends on how you share it. I've seen some budget setups where a single AC filament supply was used for a pair of outputs with a common self-bias resistor and bypass cap via the center-tap. Granted it works, but wherever the hum levels wind up, there you are... no ability to adjust.
I would suggest using a DC supply as AC filaments will still yield some hum with fixed bias. In particular which DHT are you planning on using? I have found that NOS 45 in ST glass tend to balance well (using a padded hum pot) with AC, better than most 2A3 (dual-paralleled triodes) DHTs. A single plate 2A3 is a nightmare with AC filament, pretty much the same for a 300B due to the center-tapped filament setup.
Regards, KM
I would suggest using a DC supply as AC filaments will still yield some hum with fixed bias. In particular which DHT are you planning on using? I have found that NOS 45 in ST glass tend to balance well (using a padded hum pot) with AC, better than most 2A3 (dual-paralleled triodes) DHTs. A single plate 2A3 is a nightmare with AC filament, pretty much the same for a 300B due to the center-tapped filament setup.
Regards, KM
I did it using a single voltage supply and a separate CCS for each filament.
http://www.ecp.cc/less-pressivo-plus-plus.html
An externally hosted image should be here but it was not working when we last tested it.
http://www.ecp.cc/less-pressivo-plus-plus.html
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