DIY cable article...

[zed32]

i was reading through this article here about audio cables: http://www.rane.com/note110.html

according to the diagram on that page, it shows that on an XLR cable, the shield should not be connected on the female end. is this really true? because on the mic cables i've made, i left it connected at both ends. they didn't really explain why it would be beneficial to leave the shield on the "from output" side disconnected, and have it connected at the "to input" side.

 

[kessel]

sometimes it's beneficial to leave one of the ground pins lifted to prevent ground loops between the devices. ground loops are noise created in a circuit by a voltage difference in grounds (note ground is an arbitrary value in a circuit). the reason on microphones you want to lift it at the mic side of things is because the microphone is not grounded and the console/mixer is. the shield in the cable works as long as one side is connected to ground.

 

[zed32]

cool, thanks.

 

[mshilarious]

One thing to ask yourself is, self, is the mic internally grounded case to pin 1? If so, it doesn't matter if you connect it in the cable or not, it's connected. If not, then the mic might want it to be that way.

As for the male end, some manufacturers insist that proper grounding is to connect signal ground to case ground at the point of entry, and will do so in their gear. That statement will start a snowball fight, so I will duck and run

 

[cusebassman]

Sorry to dig this one up, but I am contemplating making my own cables as well, and there seems to be no final opinion here. So - let me ask this - is it safe to go ahead and connect the ground to ground pin on both ends of the cable I make, and will it have any potentially detrimental effect on my mics / preamps?

This stuff should be much easier than it always turns out to be

 

[mshilarious]

Sorry to dig this one up, but I am contemplating making my own cables as well, and there seems to be no final opinion here. So - let me ask this - is it safe to go ahead and connect the ground to ground pin on both ends of the cable I make, and will it have any potentially detrimental effect on my mics / preamps?

This stuff should be much easier than it always turns out to be

Is it safe? Yeah, it's safe. No one will die, no gear will burst out in flames. Keep the connection between case and ground as short and low-impedance as possible. I use a discarded resistor lead.

 

[dgatwood]

As for the male end, some manufacturers insist that proper grounding is to connect signal ground to case ground at the point of entry, and will do so in their gear. That statement will start a snowball fight, so I will duck and run

I tend to agree with them. If everyone did that (and if everyone used three-prong power cords), then grounding of the cable shields would be optional and would never hurt anything.

In my experience "ground loop" problems are caused by two things:

1. Crappy equipment with two-prong cables or ungrounded wall warts.
2. Poor building grounds.

Since #2 is a safety issue and has to be fixed anyway, the only one that should be important in the real world is #1. I'd like to propose that we march with flaming torches and pitchforks outside the manufacturer of every piece of A/V gear that shaves twenty cents by using a two-prong cord or an ungrounded wall wart.

(Just to clarify, there's really no such thing as a ground loop. A signal always follows a straight path to every ground, in quantities proportional to the relative resistance. So-called ground loops are really just a way of saying that the least resistant path to ground goes through the audio cable to another piece of gear because the first piece of gear is poorly built and isn't properly grounded. )

 

[dgatwood]

Is it safe? Yeah, it's safe. No one will die, no gear will burst out in flames. Keep the connection between case and ground as short and low-impedance as possible. I use a discarded resistor lead.

I just trim the wire half an inch farther back and cut the main wires shorter and loop the ground through the lug before soldering it to the ground pin. This also makes the cable hard as hell to damage even by tripping over it.