cabling question

[AdiT]

I got a cable with two wires, that on one side has a unbalanced(TS) 6.5 jack and on the other a XLR that have connected the pins 1 and 2, between pins 1 and 3 is a loop.
I have to change the jack with a XLR, apparently will be a balanced cable.
The cable is not mine so I don't know how will be use.

What pins combination should I use to be always safe, regardless the input or output(balanced or unbalanced) ?

[ef37a]

If you are changing the jack plug for an XLR (of the opposite gender from the existing one) then the cable becomes a simple XLR-XLR "balanced" cable such a commonly used for microphone connection or from certain mixers, a few AIs, to active speakers.

The connections will be,
Pin two "hot" (say red wire)
Pin Three "cold" (say, blue or black)
Pin One shield. None of the pins are linked.

There is no "safety" consideration with audio cables in terms of life and limb! Ok, it is possible some VERY powerful amps could shock you from their speaker terminals but you would have to be very wet, or very poorly and VERY unlucky!
Improper use of course COULD result in danger, mostly of fire but you cannot legislate for rank stupidity.

Dave.

[Kwackman]

If you are changing the jack plug for an XLR (of the opposite gender from the existing one) then the cable becomes a simple XLR-XLR "balanced" cable

But,

I got a cable with two wires,

Don't you need 3 cores to have a balanced cable?

[ef37a]

If you are changing the jack plug for an XLR (of the opposite gender from the existing one) then the cable becomes a simple XLR-XLR "balanced" cable

But,

I got a cable with two wires,

Don't you need 3 cores to have a balanced cable?

Well I took "two wires" to mean two core and a shield. If just single core? Yes, forget I spake.

Dave.

[Hugh Robjohns]

I have to change the jack with a XLR, apparently will be a balanced cable.

Changing the connectors will not, of itself, convert a cable from unbalanced to balanced...

I got a cable with two wires

While it is possible to convey a balanced signal on just two wires, you would not have a cable screen, which is not generally recommended for audio applications, and could not convey phantom power if that is required. Ideally you need three wires, two signal cores and an overall screen.

...one side has a unbalanced(TS) 6.5 jack and on the other a XLR that have connected the pins 1 and 2, between pins 1 and 3 is a loop.

This is the standard arrangement for connecting an unbalanced signal to a balanced input, and, in some cases (but certainly not all) a balanced output to an unbalanced destination.

What pins combination should I use to be always safe, regardless the input or output(balanced or unbalanced) ?

If the cable is a single core with overall screen, I'd hand this original cable back and start again with a new cable. And if you have XLRs at both ends there is only one way to wire the cable:

core A to pin-2 at both ends / core B to pin-3 at both ends / cable screen to pin-1 at both ends. One of the XLRs should be male and the other female, of course, and when you come to wire them up bear in mind that the pins are arranged in a mirror images, so while pin 3 is always in the middle pins 1 & 2 swap sides in the two connectors! I do not recommend linking pin 1 to the shell in each XLR.

H

[AdiT]

I got a cable with two wires,

Don't you need 3 cores to have a balanced cable?

First thanks for all the replies above.

Exactly this bother me, the cable has only two wires without a shield.
From outside looks like a microphone cable, but after I remove the jack I realize that is more a loudspeakers cable.

[AdiT]

I got a cable with two wires

While it is possible to convey a balanced signal on just two wires, you would not have a cable screen, which is not generally recommended for audio applications, and could not convey phantom power if that is required. Ideally you need three wires, two signal cores and an overall screen.

H

Using this cable with only two wires and no shield( just two conductors) is possible to connect it on both ends to XLR without any risk, even if will be connected to a microphone with/without phantom power or as a signal cable ?

I wonder if this was made using such a cable from mistake or is a reason for this configuration.

[MarkPAman]

If the two wires in the cable are twisted around each other along the cable, & you don't need phantom power then you may get away with only connecting pins 2 & 3 at each end. It will work, but could pick up unwanted noise in some situations.

I'd still get the proper cable though.

[Sam Spoons]

The loop between 1 and 3 would short out any phantom power present at the input which would not be good. You would probably get some hum if it's not shielded (unshielded cable can work for balanced connections but only if the pairs are consistently twisted as in Cat5/6 network cable). I'd take Hugh's advice and start again.

edit :- Mark got there first

[James Perrett]

From outside looks like a microphone cable, but after I remove the jack I realize that is more a loudspeakers cable.

Maybe it really is a loudspeaker cable. XLR speaker cables were common before the Neutrik Speakon connectors appeared. I'd tell the person that you are doing the job for that the cable isn't suitable for modification unless they still have a need for XLR speaker cables.

[Hugh Robjohns]

Exactly this bother me, the cable has only two wires without a shield.
From outside looks like a microphone cable, but after I remove the jack I realize that is more a loudspeakers cable.

As James says, a lot of (passive) PA and foldback loudspeakers and power amps were fitted with 3-pin XLRs in the 1970s-1990s (before the Neutrik Speakon became the default speaker/amp connector format), and other speakers and amps used mono (TS) quarter-inch sockets.

So it's quite possible that this TS-XLR cable was actually constructed and intended for connecting a power amp to a speaker, in which case two-core cable would be exactly the right thing.

I think you need to find out more about what this cable is intended to be used with and for what function. It is not suitable for carrying balanced mic level signals under any circumstances, and I wouldn't recommend it for use with balanced line-level signals or even unbalanced line-level signals.

Just say no!

H

[Hugh Robjohns]

Using this cable with only two wires and no shield( just two conductors) is possible to connect it on both ends to XLR without any risk, even if will be connected to a microphone with/without phantom power or as a signal cable ?

The first risk is of picking up interference (because there's no overall screen connected to ground).

Secondly, if used in the current wiring form with pins 1-3 wired together, phantom power will run across the capsule of a moving coil mic, at best resulting in a very thin and quiet output, and at worse burning out the capsule altogether. And any phantom powered capacitor mics probably won't work properly, if at all.

So, basically, NO, you can't use a two-core cable in applications that call for a standard balanced cable, and YES there is a risk of causing real damage...

Brand new XLRs and a few metres of proper balanced cable is so cheap and easy to find that there is no merit at all in trying to re-purpose old and inappropriate cable like this. It would also be quicker and easier to build a new cable from scratch rather than dismantle, clean, and rebuild one from used components.

H

[AdiT]

Maybe it really is a loudspeaker cable. XLR speaker cables were common before the Neutrik Speakon connectors appeared.

I didn't know that.

I'd tell the person that you are doing the job for that the cable isn't suitable for modification unless they still have a need for XLR speaker cables.

This is what I will do.

[AdiT]

I think you need to find out more about what this cable is intended to be used with and for what function. It is not suitable for carrying balanced mic level signals under any circumstances, and I wouldn't recommend it for use with balanced line-level signals or even unbalanced line-level signals.

H

This is a cable in good condition, that has not been used from a long time. The intention was to become a signal cable used only as backup. But will make a new one.