Steve Adeff said: > phasing shouldn't matter as long as the grounds are shared and > proper sizing, etc. Ground loops in proper working equipment are > formed when the impedence to ground for the two components are > different. Connecting them together then causes one of the > components to enter into the ground return of the other component. Technically, when the potential (voltage) to ground isn't the same between the two components; then there's a potential difference between the two components and currents can flow from one to the other.
In addition, when the 2 components are on different outlets, the ground wires follow different physical paths and stray 60 Hz magnetic fields will induce currents on the loops -- if the components are plugged into the same outlet, the area enclosed by the ground loop is much less and the corresponding currents are less. > As well, in theory, properly working two prong components should > never cause ground loop problems... in theory... True, but in practice, it's almost impossible to actually isolate anything, particularly with cheap power supplies grounded to the case and RCA cables (also generally grounded to the case) used for interconnects. IMHO, RCA cables are a horrible design; when you have ground currents, they run on the shield, which turns the shield (supposed to shield the inner conductor from stray signals) into a radiator. Bonding the components together with a separate ground strap (admittedly a band-aid, but often the easiest solution, particularly for those of us who can't put everything on the same outlet) provides a lower-impedance path between the components and keeps the currents off the RCA cable shield. I also note in industrial environments, millivolt sensor wires are always shielded, but the shield is only connected at one end, never both (to prevent currents on the shields). I've often wondered (but never done a good test) what would happen with RCA cables if you disconnected the shield at one end of the cables to prevent currents on the shields. Steve __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com _______________________________________________ mythtv-users mailing list [email protected] http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
