leifhellmusic wrote:Ciao Stefano!
Thanks again for your concern about my humming problems. As a matter of fact my villa has no grounded mains outlets (except from kitchen, bathrooms, garage and external outlets). In spite of this I use grounded plugs for my stereo gear (three connector cords and 3-poled plugs). The ground interconnect from the TT is connected to ground at the phonoamp.
So, as far as I understand the Ground outlet for your system is completely floating... I think there will be no chance of ground loops.
leifhellmusic wrote:I don´t now whether this might be a source for the humming. Earlier at another forum (TNT?) I put a similar question on grounding problems and was adviced to make a dedicated outlet for the stereo by using a separate ground connector attached to a copper spear in the soil in the garden. However this is not accepted in Sweden which have rather strict regulations on how to handle electricity in houses and flats.
TNT... here's where we already met! The separate ground connector would be the best solution, anyway, to insulate from noises generated on ground lines by devices and by other signalling activities.
On the net I found a device (Stop the humming filter) at http://www.lcaudio.com/index.php?page=12
Would this be somethong to use? I happen to have such a filter at home but I have never used it.
As far as I can understand, this filter does something different. It aims at reducing RF polluting the mains (both generated by your system devices and incoming from mains): that's why it has coils, VDR to protect from overvoltages and X-Y caps. A good thing for your system (even if I am not so convinced of coils in the mains).
But the filters cares nothing if (but we are not yet sure) you have a DC component on incoming mains. The 2 diodes filters it at max 0,6V. The caps smoothens harmonics generated by this "clipping" operation.
leifhellmusic wrote:The diodes and caps you suggest, are they put in some kind of box?
Well, being devices wired to mains, it would be better to keep them away from anybody/anything who might be harmed and/r create shorts.
If you have even a cheap multimeter you might measure DC voltage by inserting the probes in a mains receptacle. Beware: take care not to touch the metallic part of probes while measuring, only the insulated (typically red/black) plastic parts!!!!