RCA Caps

Thank you @almarg and @georgehifi

There is a small operation making and selling true RCA shorting plugs: Aurora Tronics in Sandy Hook, CT (phone number 203/426-9599). I bought some a couple of years ago, and they were cheap: $19.95 for 20 plugs. They also offer RCA phono cap covers (non-shorting, for outputs), at $7.95 for 20. They sent them to me with free shipping! Cardas' protective caps look nice, but do nothing, claims for providing shielding against RF and EMI notwithstanding.

@bdp24 

Thank you very much for that info. That pricing is good. Although you purchased them years ago and we know prices only head north as time marches on :)

I'll give them a call. In my case I only have phono inputs as I don't have an analog turntable. I would imagine if shorting plugs make any difference at all, shorting the phono inputs should make the greatest, so I'm intending to short those (as any other input).

I can’t envision a design in which a shorting plug applied to an RCA **input** would cause any problems. Consider the fact that the essentially zero ohm impedance presented to the input by a shorting plug is not greatly different than the very low output impedances (e.g., 10 ohms or perhaps even less in some cases) of some components that might be used to drive that input.

@almarg

Sorry to belabor this. I’m merely operating out an abundance of caution in this regard :)

I take your statement to *include* an LFE subwoofer RCA input as well as a phono input. Therefore, *any* type or kind of RCA input where audio is concerned would fall under the same umbrella where RCA shorting of input jacks are concerned.

And, I surmise the most benefit (if any benefit can be realized at all), would or should be from a phono input, which in the case of my amp has a phono input impedance of 47k Ohms, according to manufacturer spec.

EDIT: 
I also realize that operating out an abundance of caution might mean do nothing in this regard :)

Thanks for the follow-up, Hal, as it reminds me of one situation in which a shorting plug on an input could conceivably be harmful.

That would be on some power amplifiers which provide both XLR and RCA inputs, the intent being that only one of those inputs would be used. In some of those cases the signal pin of the RCA connector is wired directly to one of the two signal pins (usually pin 2) of the XLR connector. 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.

And I suppose a similar situation could conceivably arise in the case of some subwoofers, if both RCA and XLR input connectors are provided for a given signal type (i.e., for either an LFE input or an input that is intended to receive a full range signal).

And, yes, I agree with your statement about phono inputs.

Best regards,
-- Al