XLR cable conundrum

[RoadrunnerOZ]

Large capsule side facing diaphragm mics are not usually handheld so no body ground there. The mic in question was the Sony C-100 - not a handheld although the mic does have mechanical isolation to prevent handling noise.

 

[sodderboy]

Ultimately we come back to the point that what is currently considered "best practice" is half a century out of date.

In 2024 shell should be treated as "shield" and "pin 4" and considered "earth" due to electrical safety legislation and pin 1 should be treated as audio signal return. A permanent "safe ground lift" should be applied between audio ground and earth.

Equipment and cables arranged thusly still work with gear and cables based older practices, but can be guaranteed to be free from "pin 1 problems" if all devices in the system are updated to best current day practices.

Thor

Pin 1 of a mic cable is the shield of the inter-connecting cable (not in your case with the TP), not any kind of actual signal(room mic) return. "Return" alludes to an un-balanced circuit/cable, where the interconnecting shield is part of the signal circuit.
I always strip it down to a mic connected to a pre with one cable- for an active mic, the circuit always bonds to chassis(mic body) at SOME point, inside a P48 mic or inside an external power supply. That connects the cable FXLR shell to chassis by default(talk of finishes anodizing, paint, etc. aside), no need to connect "pin 4" in the cable. At the pre a quality piece of equipment will have the XLR mounted to the chassis (pin4) and connect the cable body by default as well.
Add a patchbay, closet patch panels, room panels, whatever in-between, and I still want to have a single mic chassis connected to a single pre chassis through the cable shield(or a bunch of TP wires) with no sharing along the way. Any connecting between pins 1 and 4 will violate this by connecting multiple cable shields at the room panel. If I made the panel, the connectors are verified bonded to the panel, the panel bonded to a metal box and conduit, and that has to be bonded to earth. The cable shields are passing through the pin 1 connection only.
Any connecting of pins 1 and 4 starts to mess with my perfect, isolated runs, creating multiple paths from shields to mother earth, and if I have console and other pres in racks mixed it has always increased possibility of raised noise floor issues if the shields are connected all over. Having no console is even worse.
"A permanent "safe ground lift" should be applied between audio ground and earth. . . Please expand. Has a translator chopped it into a word salad?
Mike

 

[AUDIO FREQ]

So much to read, and so many different theories and ideas.

My Mogami Gold XLR has pin 1 jumpered to the XLR connector chassis. So I suppose I will follow their design practice.

 

[RoadrunnerOZ]

Mogami make cables not audio equipment - the jumper is there as a jumper not necessarily to be permanent - jumpers can be cut to suit the audio equipment, audio equipment should not need to be modified to suit a cable unless no normal cable configuration works - in which case there’s an inherent design flaw in the equipment.

 

[RoadrunnerOZ]

Any balanced line level equipment in a studio will be checked at the time of wiring to see if one end of the pin 1 to pin 1 (or Shield in TRS) connection should be lifted.
The norm in many studios for standard wiring has been to lift pin 1 at the output of any device so that the input device shields the cable - patchbays carry the shield - the disconnect being done in the interconnect cables. This does not apply to microphones (or some equipment that is not supply grounded and causes issues).
This practice applies to installation cabling and not loose cables generally to be used with anything around the studio.
In general no studio cables have the shell (pin 4 if you like) grounded for XLR connecting cables. I have wired up (and done cable design) for many studios as well as countless small home studio setups and each installation requires to be treated individually - there are always equipment combinations that can cause ground issues. You just deal with them and never get bound up in rules that don’t apply.
Some equipment manuals specifically denote the shell to pin 1 connection to be made in the connecting cables to be used and this is obviously part of the audio/casework grounding design. If it’s not needed don’t put it in.
Many studios carry ground lifted special cables for external equipment that need them and these are marked as such.
This all changes with unbalanced gear which connects via the shield of the cable as a signal conductor so connecting balanced to unbalanced requires the grounding of pin 3 for XLR to TS cables, or the Ring in TRS to TS - (this can be done in the TS jack without pin 1 in the XLR, or S in the TRS being connected but needs to be checked in each instance for noise/ground loop).
Then the unbalanced to unbalanced gear obviously has the shield carrying signal from jack to jack (or RCA).
I have made unbalanced jack cables that use 2 core plus shield cable with the shield connected at one end only and then the cold or ground audio leg is only carried by an internal cable and the cable shield carries no signal current and acts purely as a shield. This has significantly reduced induced noise in a lot of cases where there has been interference breaking into the audio path via cable shields.