Rerurn to Romy the Cat's Site


In the Forum: Audio Discussions
In the Thread: It’s mad, mad, mad... electricity.
Post Subject: Clarification and additional testingPosted by Lx_ on: 1/3/2011
fiogf49gjkf0d
 Lx_ wrote:
If the 2000 output is really clean of any noise and only the ground carries whatever comes from the house ground, then how do you explain the tremendous sound improvement that lifting the input ground provides? I find it difficult to not incriminate the 2000, though I am more than willing to get insightful advice.

Sorry this does not make sense as I said the opposite in my previous post: the improvement I got when lifting the input ground was minor. OTOH, the improvement I got when switching from AC-with-lifted-ground mode to battery mode was tremendous.

Those were the result I had almost two years back after I had just received the PP. Following Paul's comment on trying lifting input ground, I performed additional testing yesterday. I waited for a couple heaters and the refrigerator to come on at the same time so as to have noise sources in the AC line. I went from AC operation to battery mode using the switch on the back panel (something I had not done in my previous tests). This provided a tremendous improvement to sound quality. In fact the difference was so much more than 2 years ago, but this can solely be attributed to many other improvements in my system, which has become much more capable since then, but also more sensitive.

Then I unplugged the AC cord from the PP to assess noise coming from AC ground (assuming this is the only source of noise carried over from AC, as APS claims). I could not detect any difference, though I must say that the battery getting out of power a lot faster than 2 years ago got in the way of proper testing. This means there may be a difference in SQ when running on battery with or without the power cord attached, but if that difference exists it is minor. For me this is another indication that:
- PP output is not isolated from input AC, contrary to what APS has said so far; at least not on my unit, and probably not on the newer units Romy has
- I do not have ground loop issues (or if I have, they are minor or have the same impact whether on AC, lifted-ground AC, plugged battery or unplugged battery, and in any case impact is negligible compared to AC vs. battery mode)

Rerurn to Romy the Cat's Site