David Looser wrote:

"Spike" wrote in message
.. .


Modern low-noise systems can be expected to be very much more
sensitive than those of ~75 years ago,

Do you actually mean "sensitive"? (i.e.. the input signal necessary for full
output) in which case modern domestic audio systems are no more sensitive
than those of the 1970s. Or are you saying that, being low-noise, hum will
be more apparent? But amplifier noise levels have more than adequate for
decades too, it's the background acoustic noise levels in homes which matter
here, and they have, in general, got worse in the last 50 years or so due to
higher levels of traffic noise etc.

I meant 'sensitive' as 'being able to detect ever smaller signals and
any previously unrecognised effects'.

Could it be that
bonding the neutral line to earth unbalances the mains wiring,

Well of course it unbalances it! That's the very definition of unbalanced!

I know that. The 'could be' was a bland way of leading on the main
point, which was:

leading to residual effects that could be detected?

What "residual effects" did you have in mind?

E/m fields affecting electron flow in valves (seen that enough times)
and perhaps conduction processes in semiconductors (not a field I'm
interested in). Doubtless there are others.

I am, like you I suspect, not an expert in low noise audio systems.

The ADSL broadband system works as it does because the two-wire system
is balanced. Adding imbalance at the consumer end, an all-too-often
occurrence, can lead to severe MW pickup at night, and during the day
if close enough to a MW transmitter, leading to some combination of
lowered noise margins or connection speeds.


The telephone system has used balanced wiring since the 1880s, for very good
reasons. But here we are talking about a power supply. Mains transformers
inherently reject common-mode noise so it's hard to see what benefit running
balanced mains to an amplifier could have.

If you can come up with either a properly thought through theory as to the
benefits of balanced mains (not a "could it be... residual effects" kind of
half-baked hypothesis) or, better still, real evidence of an audible
improvement I'd be interested to see it. But if not.......

I've no intention of coming up with 'a properly thought through
theory', and I suspect that if you could, you would have done so
before now. But to take the line that because you can't think of
something that has not yet been detected simply isn't a viable
methodology. The reverse is usually true: LHC, anyone?

--
from
Aero Spike
Not a member of the RSGB since 1959