# RFI noise interference with RCA cable



## dikyllis

RFI noise interference with RCA cable, should be the root cause, since I took them out of the amp and no more noise/radio signal

 I know there are things ferrite rings, but what else?

 another shield on top?


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## sejarzo

What sort of RCA cable construction--coax or shielded twisted pair?


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## dvw

Quote:


  Originally Posted by *dikyllis* /img/forum/go_quote.gif 
_RFI noise interference with RCA cable, should be the root cause, since I took them out of the amp and no more noise/radio signal

 I know there are things ferrite rings, but what else?

 another shield on top?_

 

I think you have ground loop. Does the noise sounds like a hum?


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## dikyllis

Quote:


  Originally Posted by *dvw* /img/forum/go_quote.gif 
_I think you have ground loop. Does the noise sounds like a hum?_

 

not hum, radio station signal


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## dvw

The source of the interference can be either the cable or the source. you have already eliminated the amp (I'm assuming the amp is properly grounded).

 If it's the cable, the cable might not be properly shielded. Switch to a know non issue cable. You must have more than one cable and one system right.

 If switching cable didn't work, you can add magnet. But usually adding magnetic reduces emission more than shieding emission. You can also add a inductance or a capacitance to ground.


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## dikyllis

Quote:


  Originally Posted by *sejarzo* /img/forum/go_quote.gif 
_What sort of RCA cable construction--coax or shielded twisted pair?_

 

using Nanotec Golden Strada #201: Dual Core Shield Cable


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## sejarzo

Unfortunately, I don't speak Japanese and can't find any English descriptions of the actual construction of that cable. Seems to me that the shield is improperly terminated.

 That is completely inexcusable for a cable that appears to retail for $895 for a 1 meter pair, if I'm interpreting the info from an Audiogon page correctly.


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## Sovkiller

To me it is RFI, and this is due poor shielding in the cable, if the source and amp was working before porperly...my suggestion get a BJC for cheap with extra shielding, they offer one specially for those problems, just ask them, and try it out to see if the problem goes away...if not return them for a full refund...


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## dikyllis

is it the RCA cable acting as an atenna for the darkvoice 337 amp? although removing RCA removes the Radio signal, other cables like taralabs which I borrowed also have such problem


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## dvw

Did the amp ever worked before without any RFI?
 It is possible that the connector on th amp is defective.

 Normally for the coax cable to work and shield RFI. The external shield needed to be grounded. The shield on the cable is grounded to the cable's connector (external part of the RCA). That part is connected to the female connector on the amp which in turn connected to the ground. If any part of this ground is broken, then yes you have an antenna.

 If you have multimeter, you can try and ohm it out.

 BTW this could also be caused by cold solder joint of the amp.


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## dikyllis

Quote:


  Originally Posted by *dvw* /img/forum/go_quote.gif 
_Did the amp ever worked before without any RFI?
 It is possible that the connector on th amp is defective.

 Normally for the coax cable to work and shield RFI. The external shield needed to be grounded. The shield on the cable is grounded to the cable's connector (external part of the RCA). That part is connected to the female connector on the amp which in turn connected to the ground. If any part of this ground is broken, then yes you have an antenna.

 If you have multimeter, you can try and ohm it out.

 BTW this could also be caused by cold solder joint of the amp._

 


 I check the RCA shield is grounded, RCA plug external is grounded

 I aint sure if the amp initially work


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## dvw

Hmmm... I don't know what possibly the problem is. Something is most likely loose. Does this happen to other amp, player etc. My gut feeling is your amp might have a problem with cold solder joint.

 You need to have someone look at it.


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