Limitation on floating PS/circuit

[eboz]

What are the limiting factors for floating a particular power supply or circuit above its return potential? Is it just the transformer and wire insulation ratings? I imagine that device ratings should not be a problem, since the difference in potentials all remain the same when floated?

[Bigun]

I've never floated a supply - but the only factor I can think of that you didn't already mention is capacitance - the floating secondary of the power supply transformer will have some parasitic capacitance to the primary. Most likely it's too small to be of any consequence for audio.

[Nelson Pass]

AC power transformers routinely withstand over 2000 volts to pass Hipot
tests. You can get isolated secondaries or electrostatic shields if you
want them.

[jcx]

electrostatic shields increase C to each winding they're in between so the load effect would actually be worse

the easy way to minimumize pri-sec C is using split bobbin EI power transformers

a standard construction is "universal/international" double/reinforced insulated - for domestic line V these have to pass a 4KV HiPot test

they are actually better than many "traditional" tube power supply transformers on capacitance, insulation V rating


for even more fun you could float a single polarity supply with anti-phase driven H-bridge output