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RCA Shorting Plugs

I am coming to the conclusion that success in home audio reproduction is largely about lowering the noise floor. There are so many different types of “noise”, from so many different sources, that we only really “hear” by their absence.

I have had caps on the unused RCA inputs of my ASL passive autoformer preamp, ever since a friend suggested them way back. I recently got some actual shorting plugs (with resistors), from Hifi Collective in the UK, to replace them. I was surprised by how much difference they made. Transparency, resolution and musical flow all increased, along with the “realness” of instruments and voices. There is also more sense of the space around them.

I know some preamps short the unselected inputs, but, if yours doesn't, these shorting plugs are inexpensive, and definitely worth trying.
tommylion
georgehifi's avatar
georgehifi
10,312 posts
 
If the selector switch is not switched to the input/s that you have the shorting plugs on, it is an open circuit, and a shorting plug should have no effect on an open circuit as it is not connected to in your case the Autoformer, and in an active preamps case, to the input stage transistors.

Cheers George   
stringreen's avatar
stringreen
6,468 posts
 
absolutely no difference in my system
kalali's avatar
kalali
1,977 posts
 
I think its effectiveness could also depend on the design of the selector switch. Most high(er) end preamps have relay actuated selector switches which should completely isolate the unused inputs from the one in play.
gdhal's avatar
gdhal
1,641 posts
 
Like many other threads on this forum that are essentially duplicative, I recently resurrected an older topic related to this subject.
https://forum.audiogon.com/discussions/rca-caps

Given the input (no pun intended) of Al and George (and others, thank you, btw) I will be giving this (shorting inputs) a try within a month or so. I’m hopeful to have the same or similar results to the OP, and agree that the noise floor is an important aspect to get under the best control possible (i.e. the lower the better).
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