Cable. Balanced/un-balanced

[Josh 2]

I have done a search, but can't find an answer to a something that I'm sure is a silly question, but there often (across the web and in some manuals) seems to be conflicting info on, can anyone clarify please:-

 

I know the difference between a balanced and an un-balanced cable, but is it okay (on line level signals) to use a balanced cable between two un-balanced connections or even a balanced cable between one balanced and one un-balanced connection.

 

Thanks,

Josh.

[jamesperrett]

I know the difference between a balanced and an un-balanced cable, but is it okay (on line level signals) to use a balanced cable between two un-balanced connections or even a balanced cable between one balanced and one un-balanced connection.

 

Thanks,

Josh.

 

If you are talking about using TRS jacks connected to unbalanced TS jack sockets then it is usually OK but be aware that very occasionally you may find a socket where the screen connection happens to lie on an insulation ring on the TRS plug when mated which will may result in a loud buzzing sound.

 

If you are mixing balanced and unbalanced gear you need to be aware of the manufacturer's recommended wiring schemes - especially when going from balanced to unbalanced. If you get it wrong then you will end up with a noisy signal or, possibly in the worst case, a damaged output stage.

 

Cheers

 

James.

[Jivemaster]

Have you looked in the Yamaha sound re-inforcement handbook. Lots of suggestions in there. Balanced to TRS jack, Balanced to phono, and others.

 

Likely it will work, sometimes it will hum badly, just a slight possibility of damage, so check every situation. Get some 1:1+1 transformers for the really odd situations.

[Chris Beesley]

Here are two handy links courtesey of the guys at Soundcraft...

 

PDF1

 

PDF2

[StevieR]

Most of the time yes. But it will depend on the wiring in the sockets at either end. We have a Gemini DJ mixer with a 1/4" jack socket for the mic. When we tried plugging one in with a balanced jack it didn't work. Swapping this for a mono jack connection solved this. So there is obviously something different with the contacts in the socket.

 

Steve

[J Pearce]

This seems to be a regular problem with Gemini kit. I've had it before, and I've seen other people have trouble with it.

[Johnno]

Jensen Transformers and the Rane Corporation both publish short technical notes on Balanced connections. Quite readable. See their websites. If you can't find them PM me and I'll track 'em down.

[J Pearce]

This explains it, and also goes into the whys and hows.

[Josh 2]

Thanks Everyone,

 

I guess (to be sure) it's a case of taking each application as it comes and obtaining/making a suitable cable.

 

I asked because I'm looking to buy a stage box and most seem to be all XLR/balanced. I think I will need to convert some of the connectors to jack and was trying to work out whether to use TR or TRS.

 

Josh.

[jamesperrett]

I asked because I'm looking to buy a stage box and most seem to be all XLR/balanced. I think I will need to convert some of the connectors to jack and was trying to work out whether to use TR or TRS.

 

In this application you would normally use a DI box to convert the unbalanced signal to a balanced mic level signal and feed all the channels to mic inputs on the mixing desk.

 

Cheers

 

James.

[Josh 2]

In this application you would normally use a DI box to convert the unbalanced signal to a balanced mic level signal and feed all the channels to mic inputs on the mixing desk.

 

Cheers

 

James.

 

Thanks James,

 

I'm not sure the same applies. At the moment, I'm more thinking of converting some of the multicore/stage box sends (from the mixer back to stage amp) to jack connections, but having read up on some of the info given by others I'm still trying to de-confuse myself on whether I can run long lengths of balanced cable when the end connection (at stage amp) is counter-wired 'un-balanced' ie... I'm not sure if it then becomes an un-balanced connection/cable with regard to limiting the length of run!.

 

Josh.

[jamesperrett]

I'm not sure the same applies. At the moment, I'm more thinking of converting some of the multicore/stage box sends (from the mixer back to stage amp) to jack connections, but having read up on some of the info given by others I'm still trying to de-confuse myself on whether I can run long lengths of balanced cable when the end connection (at stage amp) is counter-wired 'un-balanced' ie... I'm not sure if it then becomes an un-balanced connection/cable with regard to limiting the length of run!.

 

This is more difficult to advise as the best solution for your situation depends on the design of the output from your mixer and possibly the design of the input on the amp. Unbalanced connections will often work fine, especially if you are using good quality cable routed away from sources of interference, but a proper balanced connection is possibly more robust when it comes to interference. I would be tempted to stick with XLR's on the boxes as make up adaptor cables for each specific amp. You might also look at using a transformer on the output of the desk and input of the amp in order to make it a proper balanced connection if interference is an issue.

 

Cheers

 

James.

[Josh 2]

James,

 

Thanks for the info., all understood.

 

I'm just off to do some more reading about transformers.

 

Josh.

[Guest bugmenot]

There's seems to be a discrepancy between the Rane and Soundcraft docs posted here. For Unbalanced TS jack to male XLR connections, Rane says (diagram 13):

 

TS Tip <--> XLR pin 2

TS Sleeve <--> XLR pin 3

XLR pin 1 connects only to cable shield

 

And Souncraft says:

 

TS Tip <--> XLR pin 2

TS Sleeve <--> XLR pins 3 and 1

 

Can anyone here sort this out for me?

[J Pearce]

The Soundcraft assembly makes the whole cable fully unbalanced.

The Rane version pseudo balances the jack.