Guys ..just to be clear...there is no connection in a turntable between power and audio...omg..if there was, we would be in trouble
The power is used strictly to run the platter and any circuit based auto functions. It does not run through nor attach to the cart/tonearm/rca's. The electrical signal used is generated by the coil in the cart through the wires to your RCA's. Period.
"Oh yeah mister smarty pants, then why do I need a ground cable" Good question Simon, I will endeavor to answer.
The ground wire is used to ground the chassis so no electrical interference can come into play as a 60hz "hum". A ground is basically a loop of energy that needs some place to go, always following the path of least resistance. If you don't have a ground wire, there where is that chassis ground loop of energy going to go ? Well, since the tonearm is on the chassis, there is a good spot !!! It will now create electrical interference. Since the cart is so sensitive (4.0mv MM or .4mv moving coil...we are talking small) it will be presented as a hum...a steady electrically induced signal as that energy exits the RCA's along with your audio signal.
"Okay professor, if that's true, why do I have a friend who has a turntable and no ground wire AND no hum". Another good question.
It can be one of two reasons. If the TT maker utilized a 3 prong plug, then the table is grounded via the AC ground wire. Adding another in fact could CAUSE a hum as you would create a ground loop.
Another reasons could be the designer used the RCA shielded end as the ground (not my cup of tea) to send that nasty old loop of energy away.
"gee..you seem to know what you are talking about. Okay, would it help my sound if I got a really good power cord !!!" Hmm...
Changing your power cord should have no affect on audio quality whatsoever unless the original cord is faulty . In fact, some changes could be detrimental. Say you changed from a 2 prong to a 3 prong grounded. You run the risk of introducing a ground loop, potentially getting house ground noise into the chassis and into the audio stream. I say potentially as the ground wire may help or may actually create the dreaded ground loop.
The best bet here is isolation. Your power is to run your platter a the correct speed and your cartridge supplies the millivolts of energy to become music. Any cross of the two is detrimental and changing the one (AC cord) has no significant benefit.
Homework for tonight
Why does a tonearm have a separate ground wire and why is it often connected to the same ground as the chassis?
