I want to use a 24V PT for tube heaters, using the two 12V secondaries in parallel to provide the left/right channels with separate supplies. I also need to elevate to a small DC reference. Should I make artificial center taps for each side and connect those to my DC reference, or should I skip the center taps and simply tie the DC to one side of each full-wave bridge?
EDIT: Just to add, this is for indirectly heated small signal tubes.
EDIT: Just to add, this is for indirectly heated small signal tubes.
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It may depend on how good your wiring layout is, and whether your AC heater powered valve circuitry is prone to hum coming via the heater to cathode interface.
If you ground just one side of a DC heater supply (that is derived from the AC heater voltage), then the AC heater voltage has a much higher AC voltage swing around 0V ground, and that may cause inadvertent capacitance coupling of AC heater hum in to nearby sensitive circuitry, or via valve cathode circuitry.
If you ground just one side of a DC heater supply (that is derived from the AC heater voltage), then the AC heater voltage has a much higher AC voltage swing around 0V ground, and that may cause inadvertent capacitance coupling of AC heater hum in to nearby sensitive circuitry, or via valve cathode circuitry.
So perhaps it's safer to use artificial center taps for both my AC and DC heaters? I will follow standard lead dress and wiring layout best practices, but it's simple enough to create the artificial center taps if they provide extra stability.
I have separate 24VCT heater transformers for the AC and DC heated stages, so no worries there.
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