RCA Caps

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

You're welcome @almarg  

And, thank you too!

I don't believe the RCA/XLR input scenario applies in my case. I'm using a Musical Fidelity M6si (which has phone RCA in) and Golden Ear Triton Reference (which has LFE RCA in).

I believe the scenario you are speaking of, where the RCA and XLR input is "shared" (i.e. one or the other) would be, for example, a Pass Labs INT-250. It's 1 and 2 inputs support RCA and XLR, however, it doesn't appear as though that unit wants both RCA and XLR connections in its 1 and/or 2 inputs simultaneously.

Yes, exactly, @gdhal . From the manual for the INT-250:

There are four inputs, two with XLR and RCA and two with RCA only. The XLR and RCA inputs on INPUT 1 (and INPUT 2) are connected so use XLR or RCA but not both. When using INPUT 1 & 2 with RCAs you should have the XLR shorting jumpers in place.

It’s unusual, though, for inputs of an integrated amp to be configured like that. Typically that situation arises with power amplifiers. But I suppose Nelson wanted to provide users with some added flexibility, by making it possible for those inputs to be used with either type of connection. While another designer might have simply made inputs 1 and 2 XLR only.

So with the INT-250 a shorting plug should not be put on the RCA connectors of inputs 1 and 2 if the corresponding XLR connector is being used.

Best regards,
-- Al

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

Appreciate that recommendation, but it appears to be a dead-end. The number is not valid, and the 860 version of CT area codes is a different organization. Googling for this outfit is also unsuccessful.

So, are there any other recommendations as to where to obtain caps and shorting plugs?

Search at eBay for "RCA shorting plugs" (without the quotes) and you'll find numerous sellers offering them, at low prices.

Best regards,
-- Al