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In the Forum: Audio Discussions
In the Thread: It’s mad, mad, mad... electricity.
Post Subject: PP input linePosted by Lx_ on: 1/4/2011
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 Paul S wrote:
Lx_, I can't tell from your post if it was/is clear to you that I suggested lifting only what APS refer to as the "safety ground", as opposed to the "neutral" wire.  In most systems, the neutral is white, and the "ground" is green.  In the USA, this would ba a fourth lug on a 220 service plug/outlet.

Yes, this is what I tested first two years ago: I suspected noise coming back on the ground line (yellow and green here), so I used a cheater plug to have only the hot and neutral connected and the ground lifted. This provided marginal improvement.

 Paul S wrote:
My comment on the "dedicated home run (neutral)" means a dedicated, "unbroken" neutral wire running continuously from the PP alone, clear back to the main neutral/ground bus, in the main service box.  If indeed noise on the neutral wire is a problem, then this represents one's best chance to quell such systemic ground noise.  If any problems getting through the PP arrive via the "hot" wire(s), then no amount of messing with wire configuration will stop the noise; only unplugging the thing would do it.

I am currently living in a flat so I cannot run a cable to the main box in the building. Only the breaker box is accessible in the flat. Considering that I already have the PP alone on one circuit, I fail to see how a different neutral would be better. It may even have the potential to form a very big loop with the hot line being able to pick up a lot of EMI, much more than two conductors being twisted in the same sheath.

Also note that APS has always claimed that they regenerate the hot/neutral signal and that it is completely free of any problem/noise that may be carried in the input hot/neutral lines. If that was true there would be no need to do anything special about the incoming hot/neutral AC. Now I believe this is not so: Romy's "upgraded" units and mine show that they are very sensitive to AC quality. For me this is true even when ground is lifted. I think Romy uses dedicated ground lines that should have no noise, though trying to lift that ground would be interesting. Also Romy suggests that even its old, well-performing PP was still sensitive to input AC (I have yet to read his post about this). So it seems that the PP is indeed not completely immune to incoming AC noise, and any solution to lower that sensitivity would be more than welcome.

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