# Balanced vs unbalanced



## Vital (Feb 23, 2010)

I see "balanced" often when looking at RCAs and also on some line drivers info.
Don't know if "balanced" means the same thing in both cases but since i have no idea what it does mean figured i'll ask here.

Can i has edumecation on this subject?


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## Ruleslawyer (Jun 15, 2011)

Vital said:


> I see "balanced" often when looking at RCAs and also on some line drivers info.
> Don't know if "balanced" means the same thing in both cases but since i have no idea what it does mean figured i'll ask here.
> 
> Can i has edumecation on this subject?


Normal RCA cables have a positive center post, and a ground jacket.

Balanced RCA cables have a positive center post and a negative jacket. That means its the positive signal inverted kind of like an out of phase speaker.

Since balanced cables are twisted, and noise in one wire will be in the other. By calculating the difference in these signals, you can figure out what is noise and remove it.

This is really a differential setup. True balanced cables have a 3rd ground conductor. XLR, for example.


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## Vital (Feb 23, 2010)

so one isn’t necessary better then other? "Balanced" does sound a lot cooler and more "official" lol

If so then what about Line Drivers/Voltage output?


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## Ruleslawyer (Jun 15, 2011)

Vital said:


> so one isn’t necessary better then other? "Balanced" does sound a lot cooler and more "official" lol
> 
> If so then what about Line Drivers/Voltage output?


Well, the 3 conductor balanced would probably have less chances for things like ground loops. Maybe someone else can explain that more fully?

What about line drivers? They are basically a pre-amp. Amp your signal near your source before noise gets in, and it means that your amp sees a better S/N ratio on its end. In theory anyways. Some amps to fine with a low voltage signal. Some cars are noisier than others. Adding another device in your signal chain is generally undesirable IMHO. Other thing many line drivers do is convert balanced input to unbalance output so you can use a wider array of amps.*

*If you have a HU with balanced out.


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## dogsbark26 (Feb 10, 2009)

To the best of my knowledge there is no such thing as a balanced RCA.

This is because a balanced connection requires three conductors (as Ruleslawyer says). Positive signal, negative signal, and ground.

It is not possible to use a RCA connector for a balanced connection requiring three conductors because it only has two conductors.


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## imjustjason (Jun 26, 2006)

AudioControl does it.

Mobile Audio FAQ


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## Viggen (May 2, 2011)

So are XLR cables better in a car vs RCA's?

My amps accept XLR, just can't decide if I should go that route or stick with RCA's


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## Ruleslawyer (Jun 15, 2011)

Viggen said:


> So are XLR cables better in a car vs RCA's?
> 
> My amps accept XLR, just can't decide if I should go that route or stick with RCA's


Do you know what your HU outputs?


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## ousooner2 (Jan 6, 2011)

Do all Audiocontrol units accept balanced signals?? I've got an Acura TL with balanced and my amps don't accept it (aka NOISE!). Looks like its up to Audiocontrol or RF-BLD as I don't have the $$$ for processor right now

_very sorry..don't mean to hijack or throw the thread of course. Just seemed like it could be useful in here to if searched._


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## Ruleslawyer (Jun 15, 2011)

ousooner2 said:


> Do all Audiocontrol units accept balanced signals?? I've got an Acura TL with balanced and my amps don't accept it (aka NOISE!). Looks like its up to Audiocontrol or RF-BLD as I don't have the $$$ for processor right now
> 
> _very sorry..don't mean to hijack or throw the thread of course. Just seemed like it could be useful in here to if searched._


Hi Trunk Monkey!

Not sure about all of them, but you'd want the matrix, which does. 6 channel line driver balanced>unbalanced conversion. Somone has one for $125 in the classifieds here.


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## sqshoestring (Jun 19, 2007)

We are talking about balanced and shielded. 

Normal RCA are shielded, with a center signal wire that is shielded with an outer jacket or 'shield' of wire or foil sheath that is grounded to get rid of noise it picks up. Coax cable on TV/cable/dish/auto antennas is the same thing to better spec. Even cell towers use huge coax up the tower. Note that with RCA you have two signal wires for 2 channels, and each one has its own shield.

Balanced is or should be twisted pair as used on most PC networking and telco wire/cable. If it is balanced you want both wires to pick up (or be exposed to) the same amount of noise, so you twist them to help that happen, and then reject the common noise in both to get your signal clean. This is done by inverting that non-signal wire and merging it with the signal wire so the noise is cancelled. The amount of twist depends on what you want, more twist takes out more noise but uses up more wire. Some pair are not twisted much at all. Most cable spec will require a certain twist per foot/etc.

XLR and other cables like some network cables use balanced *and* shielded. This is twisted pair with a shield over the whole thing. It can have one or many pairs inside the shield. The shield is grounded and then the balanced pairs inside are inverted....this gives two measures against noise infiltration into the signal line(s).

However with audio equipment that was only balanced twisted pair you could easily use two pair shielded cable and ground it to add shielding to it. If something like cat5 is shielded use that the extra pairs should not matter if you don't use them. I'm not sure I'd bother unless you had noise problems.

In reality you should not use a shielded typical RCA for balanced, because the shield will pick up more noise than the signal, and when you invert them it will not cancel all the noise. However people do it and it seems to work. Some RCA are twisted but the ones I have look like each signal is shielded alone anyway, it should be twisted pair inside one shield not shielded then twisted, though it might be a little better than no twist it is still not right. I have no data to back that up just have read that is how balanced works and each signal wire needs the same exposure to noise either in or outside of shielding so the signal and non-signal wire cancel out properly.

On top of all that audio stuff in cars appears to handle balanced in different ways, some will accept balanced or unbalanced some will not.


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## Viggen (May 2, 2011)

Ruleslawyer said:


> Do you know what your HU outputs?


I haven't actually purchased a deck yet.... waiting for the AC to be fixed on the car then install my setup. I am leaning towards Clarion's CX-501 & their site claims 4v preouts. I have the old Adcom amps, they like lots of v on the input. I can't find any rca to DIN x-overs other then the old Adcom stuff I have, it's just I am fixed to a 90hz x-over point, not sure I want that.


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## stuman (Jan 29, 2012)

sqshoestring said:


> We are talking about balanced and shielded.
> 
> Normal RCA are shielded, with a center signal wire that is shielded with an outer jacket or 'shield' of wire or foil sheath that is grounded to get rid of noise it picks up. Coax cable on TV/cable/dish/auto antennas is the same thing to better spec. Even cell towers use huge coax up the tower. Note that with RCA you have two signal wires for 2 channels, and each one has its own shield.
> 
> ...


I am trying to search balanced output and come across this thread. 

My OEM head unit has balanced output preamp signal ie. it has +,- and ground Shield for each channel, if I connect them to a/d/s 642ix which accept 
balanced signal/high level input (+,-). is the shield/ground signal goes to signal ground? ( there is five signal ground from HU: FR,FL,RR,RL and Sub and only one signal ground)

should I just ignore signal ground?


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## dogsbark26 (Feb 10, 2009)

No! You are calling the third conductor in a balanced cable the "ground shield". The "ground shield" in a balanced connector is not part of the signal path.

I don't know what you mean "signal ground". Balanced cables generally contain three conductors: Positive signal, Negative signal, and Shield (that you are referring to as a "ground shield" which is understandable because this conductor is intended to be grounded).

You can just leave the "ground shield" disconnected. Some installers ground only at one end. ie. EITHER head unit end OR amplifier end. Either way, NOT signal ground.

Experiment with which end (or both) of the "ground shield" to chassis ground to see what works best in your installation.


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## stuman (Jan 29, 2012)

dogsbark26 said:


> No! You are calling the third conductor in a balanced cable the "ground shield". The "ground shield" in a balanced connector is not part of the signal path.
> 
> I don't know what you mean "signal ground". Balanced cables generally contain three conductors: Positive signal, Negative signal, and Shield (that you are referring to as a "ground shield" which is understandable because this conductor is intended to be grounded).
> 
> ...


On a/d/s 642ix power connector, there are 4 connection
1. Power ground
2. +12V
3. remote lead
4. Signal ground 
per manual: connect signal ground to power ground at 642ix, head unit or 
chassis only if low level inputs are not used.

upon reading the manual again, you are right that signal ground has nothing to do with shielded ground which need to be left alone

So far for the install, the installer use the post OEM amp speaker level. I am planning to go back and have him connect the pre OEM amp balanced signal.
Thanks again for the clarification


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