You are here

cabling question

Customising, building or repairing your own gear? Need help with acoustic treatment or soundproofing? Ask away…

cabling question

Postby AdrianTatar » Thu Jan 12, 2017 7:26 am

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) ?
User avatar
AdrianTatar
Regular
Posts: 268
Joined: Thu Aug 28, 2014 11:00 pm
Location: Ro

 


Re: cabling question

Postby ef37a » Thu Jan 12, 2017 8:53 am

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.
ef37a
Jedi Poster
Posts: 7444
Joined: Sun May 28, 2006 11:00 pm
Location: northampton uk

Re: cabling question

Postby Kwackman » Thu Jan 12, 2017 9:01 am

ef37a wrote: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,
AdrianTatar wrote:I got a cable with two wires,

Don't you need 3 cores to have a balanced cable?
User avatar
Kwackman
Frequent Poster
Posts: 826
Joined: Thu Nov 07, 2002 12:00 am
Location: Belfast

Cubase, guitars.


Re: cabling question

Postby ef37a » Thu Jan 12, 2017 9:10 am

Kwackman wrote:
ef37a wrote: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,
AdrianTatar wrote: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.
ef37a
Jedi Poster
Posts: 7444
Joined: Sun May 28, 2006 11:00 pm
Location: northampton uk

Re: cabling question

Postby Hugh Robjohns » Thu Jan 12, 2017 9:44 am

AdrianTatar wrote: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
User avatar
Hugh Robjohns
Moderator
Posts: 17731
Joined: Thu Jul 24, 2003 11:00 pm
Location: Worcestershire, UK

Technical Editor, Sound On Sound


Re: cabling question

Postby AdrianTatar » Thu Jan 12, 2017 11:54 am

Kwackman wrote:
AdrianTatar wrote: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.
User avatar
AdrianTatar
Regular
Posts: 268
Joined: Thu Aug 28, 2014 11:00 pm
Location: Ro

 


Re: cabling question

Postby AdrianTatar » Thu Jan 12, 2017 12:21 pm

Hugh Robjohns wrote:
AdrianTatar wrote:
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.
User avatar
AdrianTatar
Regular
Posts: 268
Joined: Thu Aug 28, 2014 11:00 pm
Location: Ro

 


Re: cabling question

Postby MarkPAman » Thu Jan 12, 2017 12:31 pm

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.
User avatar
MarkPAman
Regular
Posts: 445
Joined: Wed Apr 05, 2006 11:00 pm
Location: Somewhere between Portsmouth & Chichester

 


Re: cabling question

Postby Sam Spoons » Thu Jan 12, 2017 12:32 pm

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 ;)
User avatar
Sam Spoons
Jedi Poster
Posts: 4038
Joined: Thu Jan 23, 2003 12:00 am
Location: Manchester UK

Mr G J Guitarist


Re: cabling question

Postby James Perrett » Thu Jan 12, 2017 12:35 pm

AdrianTatar wrote: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.
James Perrett
Moderator
Posts: 6029
Joined: Sun Sep 09, 2001 11:00 pm
Location: The wilds of Hampshire

JRP Music - Audio Mastering and Restoration.
http://www.jrpmusic.co.uk


Re: cabling question

Postby Hugh Robjohns » Thu Jan 12, 2017 1:20 pm

AdrianTatar wrote: 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
User avatar
Hugh Robjohns
Moderator
Posts: 17731
Joined: Thu Jul 24, 2003 11:00 pm
Location: Worcestershire, UK

Technical Editor, Sound On Sound


Re: cabling question

Postby Hugh Robjohns » Thu Jan 12, 2017 1:25 pm

AdrianTatar wrote: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
User avatar
Hugh Robjohns
Moderator
Posts: 17731
Joined: Thu Jul 24, 2003 11:00 pm
Location: Worcestershire, UK

Technical Editor, Sound On Sound


Re: cabling question

Postby AdrianTatar » Fri Jan 13, 2017 6:39 am

James Perrett wrote:
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.
User avatar
AdrianTatar
Regular
Posts: 268
Joined: Thu Aug 28, 2014 11:00 pm
Location: Ro

 


Re: cabling question

Postby AdrianTatar » Fri Jan 13, 2017 6:49 am

Hugh Robjohns wrote:
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.
User avatar
AdrianTatar
Regular
Posts: 268
Joined: Thu Aug 28, 2014 11:00 pm
Location: Ro

 



Who is online

Users browsing this forum: No registered users and 1 guest