jumper pins for xlrs

If you are referring to jumpers that connect pins 2 and 3 together on xlr input connectors, no you won't be hurting anything by not connecting the jumpers. Most likely there won't be any perceivable sonic penalty either. At most there might be a very slight increase in background noise levels.

Regards,
-- Al

I disagree. There will be a sonic penalty. That is why the manufacturer includes jumpers, not only so you have something to lose and fret over! ;^) Make certain your amp should have them before using them. You can make them out of solid core copper wire bent around a pair of needle nose pliers and cut to lenght.

length, sorry

Steve,

What is the experimental or theoretical basis of your disagreement? And what sort of sonic deficiencies are you envisioning, beyond the possibility I mentioned of a minor increase in background noise levels?

Elaborating on my previous response, leaving pins 2 and 3 of a line-level xlr input not connected together will only cause audible symptoms if ALL of the following conditions are satisfied:

1)Noise/hum/emi/rfi etc. is picked up or coupled onto pin 2 and/or pin 3, or the associated internal wiring.

2)That pickup occurs to a DIFFERENT degree on pin 2 than on pin 3, OR that pickup is great enough to overcome the common mode noise rejection capability of the input stage to which those pins are connected (and if the noise environment were that great the un-jumpered input is likely to be the least of the problems that are present).

3)There is a path for the differential noise to be coupled into the internal signal path through which the unbalanced rca input is processed. If a switch is present to select between the balanced and unbalanced inputs, no such path exists. If there is no switch, any such coupling is still likely to be minimal.

4)All of the above factors are present to an audibly significant degree.

In terms of my experience, one of the two balanced inputs on my Classe CP-60 preamp is unused, and I have never bothered to put a shorting jumper on it. More significantly, however, in the same living room I have extensive experience using high quality pro audio equipment for voice recording purposes, the equipment having numerous unterminated xlr microphone level inputs. Since they are microphone level, and subject to amplification that is vastly greater than the amplification that is applied to the line-level signals the op is apparently referring to, that sort of situation figures to be far more sensitive to the effects I have listed above than the op's situation.

My results have been exemplary in terms of noise performance and sound quality (to the extent that I can judge it on spoken voice, and by measuring the noise levels via professional software). Furthermore, that sort of quality pro audio equipment is normally not supplied with xlr jumpers for either mic or line-level inputs, and I have never heard of that kind of equipment being used with jumpers. I see no reason that an xlr input on a piece of consumer gear would be any different in that respect, especially at line-level.

Regards,
-- Al

Well Al, why even bother with balanced equipment then?

My experience is with my associated system gear, and I do believe it makes a difference, for the reasons you state...The balanced differential cancels out the distortion.

Although I disagree with you, please don't take it like I'm bashing you. Hence the happy-winky face in my previous post. ;^)

Thanks Steve; no problem.

Let me make sure it's clear, though, that nothing in my posts was intended to question the advantages of balanced interfaces or balanced internal signal paths, which I am certainly a believer in. Keep in mind that a balanced input stage will still function as such, providing rejection of common mode noise that may be picked up, even if nothing is connected to its inputs.

Best regards,
-- Al

try to spin some small solid conductor wire around the pins to connect them temporarily, something similar to wire-wrap