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RCA Shorting Plugs vs Caps non-shorting ?

I have had Cardas RCA Caps on all unused inputs in my preamp for some time. I recently bought an inexpensive bunch of gold-plated Chinese RCA Shorting Plugs on eBay (Cardas has a much more expensive version). The Shorting Plugs had a dramatic impact on dynamics seemingly reducing the noise-floor. (I seem to remember that back in the 60's/70's, shorting plugs often came with the preamps and integrated amps I had then) Are there RCA jack locations that can only be served by Caps vs Plugs? The second Preamp Out and Tape Out would be candidates for Caps vs Plugs, but all other unused jacks should take Plugs. Is that correct guys?
elunkenheimer
geoffkait's avatar
geoffkait
23,365 posts
 
All unused RCA plugs should have caps, including video Inputs and outputs, even the TV unused inputs and outputs. Apologies for being mysterious. One note: the caps allegedly prevent EMI/RFI from entering through the open plugs but if you do the math the diameter of the opening is too small for almost all electromagnetic waves.
elunkenheimer OP
31 posts
 
Thanks so much for the responses guys. To be clear: Rello your suggesting that shorting plugs be put only on Inputs and on no Outputs. So "Tape In" would take a shorting plug, but "Tape Out" can only take a non-shorting Cardas cap,same for a second "Preamp Out". Geoffkait you referenced the application of non-shorting caps, but not shorting plugs. Do you agree with Rello and my summary?
geoffkait's avatar
geoffkait
23,365 posts
 
I never used shorting plugs so cannot say yea or nay. To reemphasize my point that using caps on unused inputs and unused outputs of the TV or unused gear in the room should improve the sound. This is because the caps don't have anything to do with EMI or RFI.
bdp24's avatar
bdp24
10,285 posts
 
At one of the Bill Johnson in-store appearances I attended, he told the story of a problem caused by shorting plugs. ARC had sent a pre-amp (SP-10?) to Harry Pearson for review, and soon heard from him as he was having an issue with it. The problem was traced to Harry's installation of shorting plugs into the pre-amp's output jacks. Harry's lack of basic electronic engineering knowledge had once again caused a designer/manufacturer grief!
unsound
7,366 posts
 
I've had subtle improvements using RCA shorting plugs on unused audio inputs. But rather poor results in some, but not all unused video inputs. Maybe the video problems occurred because adjacent non-RCA (S video/component) inputs for the same video input were being used, or maybe because there was an impedance mismatch? Perhaps not a problem with most of todays current DVI/HDMI inputs?
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