RCA Line Input Shielding Technique Help - diyAudio
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Old 3rd January 2011, 10:42 PM   #1
Loren42 is offline Loren42  United States
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Default RCA Line Input Shielding Technique Help

This is the proposed connection scheme, but I think I am creating an error here.

I have isolated RCA jacks for the amp input, then a 10KΩ log pot, then the driver board for the power amp.

The question is how to ground the shield. The schematic shows a single conductor with shield running from the input, to the pots, and then to the driver board. However, I am not sure if this is correct technique.

Suggestions?

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Old 3rd January 2011, 10:52 PM   #2
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IIRC the shield is attached at the source end only. So in this case at the RCA ground.

Not familiar with the amp, but 10k seems low.
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Old 3rd January 2011, 10:58 PM   #3
Loren42 is offline Loren42  United States
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Quote:
Originally Posted by SGregory View Post
IIRC the shield is attached at the source end only. So in this case at the RCA ground.

Not familiar with the amp, but 10k seems low.
Maybe I am having a brain-flatulance moment, but how does the amp see a ground reference for the input if the shield side of the input floats?
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Old 4th January 2011, 07:10 AM   #4
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Quote:
how does the amp see a ground reference for the input if the shield side of the input floats?
The confusion, IICU, is because you are using the same conductor for both signal ground and shield. If you use a cable which has two conductors + a shield, then you can separate both functions (treating signal hot and signal ground as equals) and connect the shield in whichever way you like, e.g., only at the RCA as was suggested.

However, in your case where the input jacks are isolated from the chassis, I think your proposed solution will work too.
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Old 4th January 2011, 10:40 AM   #5
Loren42 is offline Loren42  United States
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Quote:
Originally Posted by kavermei View Post
The confusion, IICU, is because you are using the same conductor for both signal ground and shield. If you use a cable which has two conductors + a shield, then you can separate both functions (treating signal hot and signal ground as equals) and connect the shield in whichever way you like, e.g., only at the RCA as was suggested.

However, in your case where the input jacks are isolated from the chassis, I think your proposed solution will work too.
Thanks. Then the better way to do this is with 2 conductor and shield:

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Old 4th January 2011, 11:00 AM   #6
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Yep, that looks right.
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