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aj113 31 March 2011

Hi all - I know the difference between a monaural TRS cable that is used for hum-cancelling balanced line, and a stereo TRS cable that carries two separate L and R signals - my question is, are the cables and connectors themselves one and the same thing?

Both functions need cables that have ground wired to the sleeve and then the 2 'hot' wires connected to tip and ring respectively, so I don't see why one cable couldn't be used for the two different functions. (Not at the same time, obviously lol)

The reason I am asking is because I need some TRS balanced patch cables but every web site I visit has them listed as 'stereo TRS cables' without any information about whether they can be used for balanced line patching too.

Thank you in advance :)

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Comments

TheJackAttack Thu, 03/31/2011 - 19:05

More to the point, wire is just wire. It doesn't care what information you send down the little copper molecules. You just make sure that the connectors are wired the way you want them and go from there.

I've posted this one quite a few times this last week but it's probably the best document on this subject.
http://www.rane.com/pdf/ranenotes/Sound_System_Interconnection.pdf

Boswell Fri, 04/01/2011 - 02:46

A balanced mono TRS cable and an unbalanced stereo TRS cable are different, although you would have to tell them apart by visual inspection and not by using a multimeter. In a balanced mono cable, both signal conductors are carried within the same surrounding screen. In a stereo cable, the two signal conductors have their own screens in order to reduce capacitance and hence cross-coupling between the channels. The connector plugs are the same in both cases.

For short distances (a metre or so), there is going to be little difference in performance between the two. For lengths of several metres, it pays to use the correct type. Most patch cables listed as "stereo TRS" are the two conductor in a single screen type, and so are suitable for balanced signal operation.

Incidentally, the third common usage of TRS jack connections, an insert cable, is universally wired as two separate unbalanced coax cables, probably because it has to break out to two TS jacks or other mono connector.

aj113 Sat, 04/02/2011 - 12:05

Ahhh.... thank you Boswell. In the back of my mind I was sure that there must be some difference between the two. I had totally forgotten that stereo cables use separately shielded signal conductors. I suppose that could potentially 'unbalance' a balanced set up, because the two signal conductors in a balanced connection actually need to be twisted together so that they receive the same interference?

MrEase Sat, 04/02/2011 - 12:17

TheJackAttack, post: 367729 wrote: More to the point, wire is just wire. It doesn't care what information you send down the little copper molecules. You just make sure that the connectors are wired the way you want them and go from there.

I've posted this one quite a few times this last week but it's probably the best document on this subject.
http://www.rane.com/pdf/ranenotes/Sound_System_Interconnection.pdf

Even more to the point, this is poor advice as wire is NOT just wire, as Boswell has already pointed out. Crosstalk, capacitance, inductance, loss and characteristic impedance can all enter the equation depending on the frequencies and length of the cable. Look more carefully at the Rane pdf and you will notice they are ALL balanced examples are as Boswell described. Not a "Stereo" cable in sight.

TheJackAttack Sat, 04/02/2011 - 15:41

You are correct and I am properly scolded subtly by one and not so muc by another.

The connections illustrated in the document are not stereo. However there are several instances of unbalanced connections and how to properly unbalance a balanced connector. And for analog connections and a short run here will be no issue using a mono cable for a "stereo" application. For digital applications, yes one wants the proper impedence etc. The OP wasn't concerned about digital. The OP was in fact looking for plane jane TRS cables.

aj113 Sat, 04/02/2011 - 16:14

TheJackAttack, post: 367879 wrote: You are correct and I am properly scolded subtly by one and not so muc by another.

The connections illustrated in the document are not stereo. However there are several instances of unbalanced connections and how to properly unbalance a balanced connector. And for analog connections and a short run here will be no issue using a mono cable for a "stereo" application. For digital applications, yes one wants the proper impedence etc. The OP wasn't concerned about digital. The OP was in fact looking for plane jane TRS cables.

The OP is looking for balanced patch cables that terminate in TRS connectors.

TheJackAttack Sat, 04/02/2011 - 17:29

What most consumer shops call a 1/4" stereo cable for headphones etc is in fact not a stereo balanced cable. It only has three wires inside just like a pro audio TRS mono balanced cable only the two main wires (left and right +) have their own shield. If you were to cut one open and do an autopsy that is what you will find. These are generally cheaply made and use minimal strands of copper and cheap end connectors. So this is really as stereo unbalanced cable.

A pro audio TRS balanced mono cable has three wires inside but there are more strands of copper per wire and usually far superior connectors on the ends. Also, both the main wires inside are wrapped in the same foil shield. Sometimes there is also whats called a drain wire but we'll leave that alone for the sake of simple explanation.

For short runs these will do the identical job though again, the pro audio TRS mono cable (the standard) has generally better wire and connectors. A headphone cable will do in a pinch.

aj113 Sun, 04/03/2011 - 01:34

TheJackAttack, post: 367887 wrote: What most consumer shops call a 1/4" stereo cable for headphones etc is in fact not a stereo balanced cable. ......

Thank you for your input, most of what you wrote has already been explained by Boswell, maybe you missed his post?

However I am curious to know what you mean by 'stereo balanced cable'. As I said in my earlier post, I am not even sure if such a thing exists, - and to clarify once more, my opening post made no mention of this term. I was asking if a stereo cable and a mono balanced cable were one and the same thing. (And now thanks to Boswell I know they are not).

TheJackAttack Sun, 04/03/2011 - 07:31

Boswell did correct my generalization from my first post. I should not have been so cavalier. Mea culpa. I come from a live audio background where people are too attached to the label and forget the function. And generally speaking again, you don't find headphone cables too much in pro audio unless you're seeking them out for replacement or extensions.

Stereo "balanced" was another typo or misunderstanding of some previous post. Sometimes reading/replying on a phone gets me in trouble. It is possible to have a stereo balanced cable but it would not terminate in a TRS connector. Usually these are 5 pin XLR cables and are usually to be found with stereo microphones.

MrEase Sun, 04/03/2011 - 16:32

TheJackAttack, post: 367879 wrote: You are correct and I am properly scolded subtly by one and not so muc by another.

The connections illustrated in the document are not stereo. However there are several instances of unbalanced connections and how to properly unbalance a balanced connector. And for analog connections and a short run here will be no issue using a mono cable for a "stereo" application. For digital applications, yes one wants the proper impedence etc. The OP wasn't concerned about digital. The OP was in fact looking for plane jane TRS cables.

My apologies for appearing too agressive - it certainly wasn't intended.

Perhaps I could more gently point out that, again as Boswell stated, using a short length of "Stereo" cable would not be too harmful if used as a balanced lead (as there will still be an element of balance to any interference from external fields) but the corollary is not so true. If true balanced cable is used, even over just a metre or so, the capacitance of the two inner leads could cause significant crosstalk at high frequencies (where the audio is most directional) and thus reduce the stereo field. How much this would affect Stereo systems would depend very much on Input and Output impedances of the gear.

aj113 Mon, 04/04/2011 - 07:26

OK guys well, Mr Ease, you make a good point. Although you may well be able to use a 'stereo' cable in a mono balanced scenario, the reverse may not be true. However, I am only concerned with buying balanced cables for my setup - (i never thought it would be so damned involved lol).

So have a look at these guys, [[url=http://[/URL]="http://www.thomann…"]THE SSSNAKE SK369S-15 PATCHKABEL - Thomann UK Cyberstore[/]="http://www.thomann…"]THE SSSNAKE SK369S-15 PATCHKABEL - Thomann UK Cyberstore[/] what do you think? Incorrect product description, i.e. they are really mono balanced cables, or are they TRS jacks wired up with stereo signal cable?

MrEase Mon, 04/04/2011 - 12:41

Hi AJ,

As Boswell said the cables in your Thomann link are not very high quality and are likely to give trouble even in studio use - don't even consider them if you are going on the road. Try this site [[url=http://[/URL]="http://music.andert…"]Andertons Music Company - Search Results for Balanced TRS cable[/]="http://music.andert…"]Andertons Music Company - Search Results for Balanced TRS cable[/] where they certainly have balanced TRS cables. In the UK you could also try GAK. I have bought (not cables) from both of these and have good service and good returns policies. Not sure where you are in the UK but Andertons is in Guildford, Surrey and GAK is in Brighton.

RemyRAD Mon, 04/04/2011 - 21:56

I really love this play on words going on here. What we're really talking about is to just use good quality microphone cable for all of your patching applications. There are special kinds of balance microphone cables known as Star Quad that actually have four active conductors and a shield. Put that in your pipe and smoke it. Balanced basically is 2 conductors and a shield. Patch cords for balanced patching purposes are 2 conductors and a shield. A balanced 1/4 inch stereo patch cord really doesn't exist as it would require at least 5 connections and you don't get five connections on a 1/4 inch patch cord. Cheap unbalanced stereo cables are cheap cables. Stick with good quality microphone cabling and you can't go wrong.

Simplicity is good
Mx. Remy Ann David

aj113 Tue, 04/05/2011 - 05:52

RemyRAD, post: 368051 wrote: ...What we're really talking about is to just use good quality microphone cable for all of your patching applications. ....

Well, no we're not actually. The topic is whether cables that are described on vendors' websites as 'stereo' cables are in fact balanced TRS patch leads. Or not.

Boswell Tue, 04/05/2011 - 08:03

aj113, post: 368079 wrote: Yes but - as I asked earlier - what kind of trouble? What is likely to happen? What is the worst that could happen?

I've worked with rigs that have had patch cables of that type. The cables tend to go intermittent after a while, generally involving broken conductors. The problem with patch leads is that by their very nature they get a lot of handling and some abuse, which the cheap cable and moulded jack plugs are not very good at absorbing.

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