This doesn't actually mean anything. What is regulated is the voltage difference between the positive rail and earth. I'm sure you had a problem of some kind but it is really caused by the black speaker connection of the 303 being floating.Another problem with the Quad 303 for bi-amping or connecting directly to a computer is that they regulate the Earth rather than the positive rail
I am going to restore a 303 and use it in a bi-amping situation. Should I replace the output caps with PP types and use it for the treble, or put some big electros in it and use it for bass?
As long as somebody is reading this 2010 thread: and I suspect Allen B the OP is not:
- Bass response is poor when comparing to a Quad 405 and Quad 306 (capacitor coupling).
I'm here, but with not much to say. I'd heard about these amps when I got my hands on one by chance and I wanted to find a use for it. It's hard to identify and be confident of its strengths when an amp needs work and may not be performing as well as it should. In any case I got it working and usable but over time I found mine had a characteristic sound that I wasn't liking, and it wasn't really what I was looking for in a subwoofer amp so it got pushed aside.and I suspect Allen B the OP is not
The 303 PSU regulates the negative line, but that is grounded.
the main PSU capacitors negative voltage will swing up and down with the load rather than the positive rail which stays fixed.
The difference is that the rail voltage regulator in the 303 has no capacitance buffer afterwards.
Ability to power a whole cycle of a bass waveform while the line voltage passes through zero once or twice is an important ability in reproducing bass.