I have a coincident phono amplifier and biamped coincident speakers with dedicated 20 A circuits from a separate panel share a common star ground (independent from rest of house).It isn't clear what you mean by " course EMF like noise ." But the problem could be your ground, which you state is not shared with the rest of your house. In the US, this would be a violation of the NEC and is potentially hazardous. In any event, if it's an unshared ground ... to what is your system grounded? It sounds like it's not bonded to the neutral in your service panel, which would tie it back to the electric utility ground. That's your best ground, which of course is supplemented with ground rods as required by code.
There is not ground hum, but when phono to amplifier interconnects connected to amplifiers a course EMF like noise occurs.
Phono interconnects acting as antenna, adding noise to system
Have interesting problem with cable related noise. I have a coincident phono amplifier and biamped coincident speakers with dedicated 20 A circuits from a separate panel share a common star ground (independent from rest of house).
There is not ground hum, but when phono to amplifier interconnects connected to amplifiers a course EMF like noise occurs. The cables seem to be acting as antennas since the noise does not change if disconnected from phono amp but stops if disconnected from power amplifier.
Interestingly, the interconnects are 12feet long running in galvanized conduits under floor to the phono amplifier
The noise is louder if i run in air outside of the conduits. When in conduits only 3 feet at either end is exposed.
does anyone have any suggestions? read that there are braided copper sleeves could try with exposed part? use tinned copper tape? or is there something else going on?
There is not ground hum, but when phono to amplifier interconnects connected to amplifiers a course EMF like noise occurs. The cables seem to be acting as antennas since the noise does not change if disconnected from phono amp but stops if disconnected from power amplifier.
Interestingly, the interconnects are 12feet long running in galvanized conduits under floor to the phono amplifier
The noise is louder if i run in air outside of the conduits. When in conduits only 3 feet at either end is exposed.
does anyone have any suggestions? read that there are braided copper sleeves could try with exposed part? use tinned copper tape? or is there something else going on?
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jricci, Does it only make the noise when you have the phono input selected, or is it when any input is selected? I ask because I just remembered that my system has a nasty noise when the phono is selected and I turn on the TV. Not sure what is causing it, but I just turn off the TV and it goes away. I don't know if the cable or the cartridge are picking up the interference. Regardless, turning off the TV resolves the issue. No other inputs are affected, just phono. |
@reubent Check out my blog post on ground loops. :) Cable TV often causes that. http://pqltd.blogspot.com/2016/11/quick-safe-and-easy-fixes-for-ground.html Jricci, Let’s assume it really is EMI/RFI that you are hearing, and not a ground loop issue. With RCA lines running that long it could be an issue and may not be solvable with just cables. Make sure your cable is 2 conductors + shield. Connect the shield and - side at the preamp side only. This may not fix the problem, in which case your choices include:
Best, Erik |
jricci Would running cables through a braided sheild in the conduit work?Before undertaking additional work, you should try correcting your improper electrical safety ground that is " independent from rest of house " and be sure that it is properly bonded to the neutral bus bar in your electric service panel. |