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What do "RCA caps" do, if anything?

post #1 of 7
12/27/10 at 7:00am
Thread Starter 

Random surfing brings you to... Well, sometimes a pile of gold, other times a pile of brown.

Today I fell upon these things. Small metal caps that cover unused RCA jacks and are supposed to do something, somehow.

I know absolutely none of this. So any of you here know of these things or use these things? What do they do (what are they supposed to do)?

Thank you very much.

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post #2 of 7
12/27/10 at 10:46am

I've seen input shunts that plug into unused RCA inputs to reduce noise. But that's not usually needed. If a receiver (for example) is set to play from the CD input, there's no harm if a tiny amount of noise comes in on the Aux input.

 

--Ethan

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post #3 of 7
12/27/10 at 11:10am
Thread Starter 
Quote:
Originally Posted by EthanWiner View Post

I've seen input shunts that plug into unused RCA inputs to reduce noise. But that's not usually needed. If a receiver (for example) is set to play from the CD input, there's no harm if a tiny amount of noise comes in on the Aux input.

 

--Ethan



OK... I once had a player plugged into "AUX" on the receiver, but with the dial set at "TAPE" I can till hear an (extremely) small amount of that music. So the caps are for that, huh.

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post #4 of 7
12/28/10 at 10:17am
Quote:
Originally Posted by 3602 View Post

I once had a player plugged into "AUX" on the receiver, but with the dial set at "TAPE" I can till hear an (extremely) small amount of that music. So the caps are for that, huh.


No, the cap / cover is still not needed. In your case music was playing at presumably full volume into the Aux input, and you heard a tiny bit of crosstalk leaking through. But with no signal playing, and nothing even connected, the noise at that unused input is at least 80 dB softer. So you'd never hear that with or without the cap.

 

--Ethan

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post #5 of 7
12/29/10 at 3:05pm

 

I've been wanting to try these caps for some time but I just haven't gotten around to it.  Plus that would require money in my wallet, and that doesn't happen often.  They block EMI that sneak in the exposed jacks.  For these to make a difference however, your system needs to be quiet enough own its own before you get to hear the effects.

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post #6 of 7
12/29/10 at 3:11pm

Tried them, use them, but they don't seem to make a difference. However, they plug up the holes rather nicely. wink_face.gif

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post #7 of 7
12/29/10 at 3:23pm

 

And is there really anything better than a plugged hole?

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