# rca interconnect - connect shield to ground ok?



## alamakazam

rca interconnect - connect shield to ground ok?

 I always had problem with RFI problem with my amp..

 I solve it by connecting the shield of cable to CHASIS ground... the noise is all gone..

 usually the shield is connected to the RCA ground, but I still hear noise in this situation

 so can I ask RCA ground and chasis ground is a different grounding source? I used multimeter to check most amps, they are isolated to each other..

so my question, is shield connected to chasis ground or even power ground is correct?


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## slowpogo

I'm not entirely sure what you're asking...but the usual procedure is to connect the shield to ground on the SOURCE end of the cable. That's why cables are given "directional" markings.


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## iareConfusE

Quote:


  Originally Posted by *slowpogo* /img/forum/go_quote.gif 
_I'm not entirely sure what you're asking...but the usual procedure is to connect the shield to ground on the SOURCE end of the cable. That's why cables are given "directional" markings._

 

Doesn't there need to be a ground connection on both ends for the interconnect to work though?


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## Mr Incredible

Yes, you connect the ground normally, then connect the SHIELD to the ground on the source end.


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## NightOwl

Quote:


  Originally Posted by *iareConfusE* /img/forum/go_quote.gif 
_Doesn't there need to be a ground connection on both ends for the interconnect to work though?_

 

Yes, but what you're probably thinking of is a coaxial cable (one central conductor surrounded by a shield) The shield acts as the signal return and has to be attached at both ends. Twinaxial, twisted pair, and star quad, etc. cables have more than one central conductor covered with a shield. The shield is not part of the signal and is only grounded at one end so that it is isolated from the signal path with less chance of introducing RF or EMI noise to the cable.


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## NightOwl

Quote:


  Originally Posted by *alamakazam* /img/forum/go_quote.gif 
_rca interconnect - connect shield to ground ok?

 I always had problem with RFI problem with my amp..

 I solve it by connecting the shield of cable to CHASIS ground... the noise is all gone..

 usually the shield is connected to the RCA ground, but I still hear noise in this situation

 so can I ask RCA ground and chasis ground is a different grounding source? I used multimeter to check most amps, they are isolated to each other..

so my question, is shield connected to chasis ground or even power ground is correct?_

 

Attaching the shield to the chassis of your amp as opposed to your rca jacks would have no effect on RFI in your cables. If anything it would make things worse.

 It sounds to me like you either have a grounding problem somewhere and the shield wire is acting as a ground wire or you had a faulty interconnect. The grounding problem could be at either end, your source or your amp. Try using different rca's connected normally. If nothing changes, then change your source. If you still get what sounds like RF, then the problem is in your amp.


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## Juaquin

Look at it this way - if the shield is connected to ground at the source, and ground is connected to both the source and destination...then any RFI in the shield is being transmitted to ground which is still attached to the destination. The RFI will still end up at the destination. You might not get AS much RFI, but you're certainly still getting most of it.

 Shielding in general definitely helps RFI, but I wouldn't worry about whether it connects to ground at whichever side.


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## Pars

At least on most solid state amps, the chassis will be connected directly to the power ground for a 3-wire power scheme, such as the US, for safety reasons. Assuming that the RCAs are isolated from the chassis (most are), the RCA ground will be tied to amplifier ground, which may or may not be the same as the power ground. The amp may have a ground loop breaker installed (small value resistor between amplifier ground and power ground; see http://sound.westhost.com/earthing.htm for example). 

 These or other factors may influence why the OP is seeing more effect by grounding the shield to the chassis instead of to the RCA jack shell. THis assumes that there are indeed two conductors (+/-) for the RCA interconnect and that the shield is really just that... a shield.


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## SiBurning

Not all equipment is made equal.

 Before you can answer this question, you need to know how the equipment is designed. Is it a floating or earth-grounded chassis? Just guessing is likely to make matters worse, and possibly dangerous.

 Want real trouble? Plug in an old piece of equipment that doesn't have a polarized plug, or a model with a polarized plug that's wired backwards.

 For a cable that has an extra shield besides the signal and returns, you can wire the shield to an earth grounded chassis on one end. That's a hack, and isn't really the right thing to do, but it's done all the time. This is good for professional equipment. Most home equipment just isn't wired like this.

 It's quite possible on RCA cabled equipment that the return side of the connector is already connected to (floating) ground, so if you fix a noise problem by connecting the shield (return) to ground, it sounds to me like your connector is loose or your cable end is bad. Heck, maybe all you need to do is find some grounding screw and tighten it.

 Maybe, maybe not. It all depends on how the equipment is designed.


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## alamakazam

I am actually using a darkvoice 337 headphone tube amp... 

 I am sure the rca ground and chassis ground(power ground) is a different ground


 I am using a twisted pair for signal, so the shield will be connected to chassis ground... I got this idea from a cable for car audio... it solved the RFI problem.

 I just wanted to be safe, if it will damaged my equipment

 with all the answers, I think it is safe ... am I right?


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## SiBurning

You're good to go, grounding at the Darkvoice end only, but you should only use cables that have a shield separate from the two signal and return cables. Do a quick check with your meter and make sure where you ground is connected to the earth pin of the power jack or the shiny metal interior plate--I don't see anything electrically connecting the black outer case.

 From http://www.head-fi.org/forums/f5/dar...review-219504/ it looks to be an earth ground chasis. I see three wires coming off the power cord, with the yellow/green wire (earth ground) connected to a screw in the chassis.

 In your situation, you might want to have a good filter strip that isolates each piece of equipment separately, since you're adding that RF directly into the ground of all your other equipment. Not critical, but you clearly have a situation where it might help. Of course that'll do nothing for the other channel of that cool dual monoblock amp, since the earth ground is shared.

 By the way, are you grounding the left channel to left ground and the right channel to right ground? <just kidding>

 I do own amps where you don't want to do this. I wasn't just being funny or picky. Two have polarized plugs, the third (circa 1980) has an unpolarized plug. Obviously, none of these are earth grounded. And, yes, that old Kenwood has shocked me plenty of times.


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## alamakazam

Quote:


  Originally Posted by *SiBurning* /img/forum/go_quote.gif 
_You're good to go, grounding at the Darkvoice end only, but you should only use cables that have a shield separate from the two signal and return cables. Do a quick check with your meter and make sure where you ground is connected to the earth pin of the power jack or the shiny metal interior plate--I don't see anything electrically connecting the black outer case.

 From http://www.head-fi.org/forums/f5/dar...review-219504/ it looks to be an earth ground chasis. I see three wires coming off the power cord, with the yellow/green wire (earth ground) connected to a screw in the chassis.

 In your situation, you might want to have a good filter strip that isolates each piece of equipment separately, since you're adding that RF directly into the ground of all your other equipment. Not critical, but you clearly have a situation where it might help. Of course that'll do nothing for the other channel of that cool dual monoblock amp, since the earth ground is shared.

 By the way, are you grounding the left channel to left ground and the right channel to right ground? <just kidding>

 I do own amps where you don't want to do this. I wasn't just being funny or picky. Two have polarized plugs, the third (circa 1980) has an unpolarized plug. Obviously, none of these are earth grounded. And, yes, that old Kenwood has shocked me plenty of times._

 

I do have filter strip, guess I am good... finally silence in my system


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