Necessary to ground and XLR interconnect?

You will get potential for hum if you don't run the shield through - normally pin 1 is ground connect the shield to here both ends. Pin 2 is positive and pin 3 is negative - nothing to do with ground :-) and remember to take a close look at those small numbers 1 and 2 are reversed in relation to 3 from the male to the female XLR

Good luck

Peter

Pbnaudio has it, that's the point of XLR. With three conductor XLR cables/inputs/outputs, the shield of the cable, designed to pick up all the stray RF and EM noise around the cable, isn't inserted into audio inputs. The shield protects the positive and negative audio signal.

Brad

With XLR signal connection/connectors, there are two possible "grounds". Signal ground and chassis ground.

Pin 1 is 'signal ground' and is the zero (0) signal reference point between pin 2(+) and pin 3(--). There is also a (fourth) connection point on the case, or barrel, of the XLR connector which is 'chassis' ground. It may or may not be the same as 'signal' ground, depending on the design of the circuit/component in question; often the 'balanced' connections in audio gear are really only pseudo-balanced; which is to say they are really two identical single ended signals, a 'hot' and a 'common' (or chassis ground) where one of the single ended signals has had its polarity inverted (the 'hot' is changed in polarity from + to --) and then it is re-combined with the non-inverted single ended signal to make a "kind of" balanced signal (which can then drive a balanced input on another component.) But it's not a true balanced output.

However, if you want to shield the signal conductors (in a balanced cable), it's best IMO to use 'chassis' ground, and connect the shield (at both ends) to the barrel of the XLR connectors. There is no need to 'float' the shield (connect it at only one end) with balanced interconnects, since there's no chance for any current that might develop in the shield to find its way into the signal path.

Just my two cents.
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Thanks-so I should connect a shield to both ground pins, not one. But if I don't want to use a metal foil/braid shield, should I connect up the ground pins with a wire anyway, or would there be no point to that? My shield will be a non-metallic outer covering--Flexo Conductive carbonized braid.

Jafreeman: What you need to do is check your equipment. I have Wadia equipment, and if I remember correctly, the XLR output connectors only have wires to pins 2 and 3, and nothing to pin 1. If there IS a wire to pin 1, however, and you still want to shield the cable, then you need to connect a third conductor wire (i.e., NOT the shield.) It won't hurt to connect the shield between pins 1 and 1, but then you're using the shield as a (signal ground) conductor, and not as a shield ;--)

To sum up, the Wadia (probably) has a pseudo-balanced outputs. So if there IS a wire to pin 1 of the output connector, then it's (probably) your normal chassis ground, and you should connect the shield to pins 1 at each end of the cable, in order to connect the grounds of the CDP and the amps together. You rarely see, even with truly balanced equipment, a situation where all three pins are connected by conductor wires AND in addition, a shield is used to connect the chassis grounds (the XLR barrel) of both components. The reason that possibility (3 pin + chassis ground) is provided, is for use in long runs of microphone lines, where the pin conductors are sometimes also used to supply DC to the mics. But for your puropses, you don't need to worry about that. BTW, you didn't say what kind of amps you have. It might help to know whether they have truly balanced inputs, like a BAT, or just pseudo-balanced inputs like many of them do.
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Nsgarch, thanks--I am connecting up a Wadia 861 to ARC Reference 210 amps, currently using Transparent Reference XLRs about 8 years old, and they have networks. I think I can do better--want to try Dueland 2.0 silver ribbons with oil-impregnated silk--no other shield is called for with these-Dueland philosophy is natural materials only. One ribbon to each (+) and (-). What should I use to connect up the ground pins, a nominal, round wire? I would isolate this from the ribbons with a Techflex carbonized braid.

Jafreeman: Of course! I should have guessed you were planning to use some exotic/esoteric wire I'd never heard of ;--) OK, Dueland makes some great parts/components, but I think your using ribbon conductors represent major overkill if you're going to be making XLR interconnects -- to say nothing of terminating them (you'll have to use pigtails ;--) It's overkill because many of the benefits such products would confer on a single ended IC are already part of balanced cable design anyway.

But go ahead! For the ground reference wire, yes "wire" is OK but it should be heavier (AWG) than the signal wires (if you even need one as I brought up earlier) and what do you plan to house/protect the ribbon cable in?

As for the shield issue, again, it's a matter of what kind of dirty electrical noise is in your environment. Balanced cables are self-cancelling in terms of the noise in the signal conductors themselves, but that doesn't make the conductors immune to external noise such as airborne RFI, and ESPECIALLY digital hash radiating from the power cords of any equipment that incorporates ANY form of digital signal processing (DSP) like digital switching, equalizers, displays, etc. (i.e. not just DACs ;--) So make sure all power cords supplying power to such equipment are shielded, and that the outlets to which you connect those cords are "digital outlets" meaning they have capacitors that allow RFI frequencies to drain to ground.

I just don't know how you're going to get those ribbons inside a shield ;~))
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