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

Showing 3 responses by jaybe

I just ordered a bunch of shorting plugs on eBay. What about for the unused spdif, XLR and USB ports, is there a need to treat these as well and are solutions available?
There are at least two types of RCA shorting plugs I’ve seen. One appears to directly connect the positive and negative sides, these are all over eBay and can be had cheap. Just a metal stamping with a plastic overmolding.

The other type has an actual resistor built into them and are more expensive.

Whats’s the difference, and are they interchangeable?

I just bought a bunch of the cheap eBay ones but am not sure they can be safely or effectively used after seeing the ones with the resistor.
@almarg 
Hi Al, appreciate your feedback. At one point you say

So if the XLR input is being used in those cases and a shorting plug is put on the RCA connector, the output circuit of the preamp or other component providing the balanced signal pair to the amp would have one of the two signals on its XLR **output** shorted to ground.

My AR pre does have both XLR and RCA inputs, I use the XLRs. So if the short to ground you mentioned happens, is that harmful to the unit or would it only result in the muting of the signal (or both?). Would I know right away from using the RCA shorting plug was having a bad effect, if any?

Thanks again.