Auxinput,
Where do you think all that constant power draw goes? It goes straight into the heatsinks. Use some thinking here. If a 30 watts amp is dissipating 120 watts in pure heat just sitting there, do you really think that's anywhere near the full extent of the power supply's capacity? Unlike a class AB amp, that thing needs to deliver close to 5.6 amp constantly assuming 32V rails, which is what you'd want. A 600VA transformer (typical for a 30 watts class A amp) is going to put 12.5 amp per rail. You're pushing that amp WAY out of class A before you peter out the power supply. You can get away with torpidly built transformers in class AB amps that run higher voltages with lower current ratings because they hardly get warm under idle. That's the major reason class AB exists. The most expensive part in the entire amp doesn't need to be as expensive.
All of that said, a well designed class AB amp with a decent regulated supply can certainly hold it's own against a similar class A amp with a massive unregulated power supply.
I know people like to think those boards with the transistors on them are the real special, expensive parts, but nothing costs more than the transformer and the chassis. That's why class A is so expensive.
Where do you think all that constant power draw goes? It goes straight into the heatsinks. Use some thinking here. If a 30 watts amp is dissipating 120 watts in pure heat just sitting there, do you really think that's anywhere near the full extent of the power supply's capacity? Unlike a class AB amp, that thing needs to deliver close to 5.6 amp constantly assuming 32V rails, which is what you'd want. A 600VA transformer (typical for a 30 watts class A amp) is going to put 12.5 amp per rail. You're pushing that amp WAY out of class A before you peter out the power supply. You can get away with torpidly built transformers in class AB amps that run higher voltages with lower current ratings because they hardly get warm under idle. That's the major reason class AB exists. The most expensive part in the entire amp doesn't need to be as expensive.
All of that said, a well designed class AB amp with a decent regulated supply can certainly hold it's own against a similar class A amp with a massive unregulated power supply.
I know people like to think those boards with the transistors on them are the real special, expensive parts, but nothing costs more than the transformer and the chassis. That's why class A is so expensive.