There has been a lot of discussion around these parts about the importance of power supply quality. Although Naim don’t generally recommend active power conditioners, things like Powerline cables are marketed as significant, and many users speak favourably about dedicated spurs and upgraded breakers, wiring and sockets have improved things.
In this context, it seems (to me) to be unlikely that supply voltage is unimportant. Is there any evidence that wimpy 120V like we have here in North America results in poorer SQ outcomes than the hairy-chested 240V those in the UK and Australia (for example) can provide? Generally speaking, our North American circuits can’t provide the same continuous amperage (possibly not important), but the lower voltage also means that transients will potentially be more affected by electrical resistance in supply circuits.
Makes little to no difference. 120v on a 20A circuit isn’t wimpy. You can install a 120v 40A circuit if you like - that would deliver more current than 240v ones in the UK.
The low resistence on your mains connection is more critical. Thick AWG wire helps power amps with transient recover (apparently). Or you could have 240v installed if you’re really fussy but it would be a waste of money. Power in north America actually comes into the home as multi phase 240v with a centre tap between each phase done at the circuit box to send 120v to rooms. A double width MCB will bridge those and give you 240v. That’s how the circuits for aircon and ovens work.
But honestly, a waste of time. Quality mains is really important. The voltage, not so much.
Simple but insightful question. Because of course, the definition depends greatly on your point of view and the sensitivities of what you are connecting to it.
I would say
Consistent voltage. It shouldn’t be 115v one second and 125v the next. Variances occur but ideally they are gradual depending on time of day if at all.
Well within the +/- norms stated for your country. Definitely want to be avoiding severe over voltage. That will cause transformer hum more often than DC offset.
Smooth sine wave. By smooth, if seen from an oscilloscope with sufficient resolution it isn’t a carrier for a piggy back network over PowerLine etc.
No significant DC offset. Audiophiles love this one. But it is no where near as common as people think.
Good ground potential. Safety ground varies from country to country but where I am (for example) anything under 1 Ohm is up to code. 1 Ohm is useless for audio noise drain. It is still too high.
Earth dedicated to the actual circuit used by the hifi. Often earth is strung around across circuits since that ticks a good enough safety box but opens up a world of ground loop possibilities.
Low resistance back to the consumer unit. There will already be thick AWG cable from there to the outside line, but thick cable from there to the socked lowers the resistance path between the hifi and the consumer unit.
Most, if not all, can be addressed by careful installation. Conditioners and so forth are a bit like taking medicine without any diagnosis from the doctor. Naim’s position is a bit misunderstood. They don’t recommend conditioners as matter of course in the same way you don’t take green pills because you might have some illness. If you have a problem and can hear it, then by all means get it diagnosed, with the help of an electrician or your dealer if possible (electricians often aren’t equipped to measure DC offset or line noise). Then find a targeted solution for that. When the problem goes away, stop using it. So many die hard Naim users put up with known issues because they think that is better than going against what Naim said (which in fact they did not mean it as a commandment). By the same token there are users who have no idea whether they have a problem or have some issue but aren’t sure what it is and blindly buy an expensive conditioner. Which, might work if you get lucky and the medicine matches the illness. or it might not.
good response there. The only thing I might question is that the connection to the transformer will use different winding ratios. I suspect this is achieved using the same physical transformer, but using different jump off points for the different voltages. Unfortunately I have no idea if this would make a difference either way, but I bet someone knows