Balanced vs unbalanced

["Tracey Gardner" <tracey.gardner@xxxxxxx>]

A quick search on Google, "balanced versus unbalanced audio"
brought
up over 1000 hits, this being one of them

Tracey

In audio applications you can encounter two types of wiring schemes.
One, using shielded cable is unbalanced where the centre conductor
of the cable carries the actual audio signal and an outside braided
shield acts as the signal return as well as a means to block extraneous
signals from interfering with the audio.
This scheme is simple but often suffers the problem of hum inducement
if the shields are not terminated properly.
The second scheme is to use a balanced configuration where the audio
is transmitted as a differential signal through two wires.
Any extraneous signal coupled to this type of arrangement winds up
being present on both conductors and tends to cancel itself out at the
terminated end. While this scheme is more interference and hum
resistant than the unbalanced mode, it requires that both signal leads
"float" from any shield.
If a shield is present, it is not connected to any of the signal leads.



> While surfing on a number of HA sites, I have come across various
> references to balanced, as opposed to unbalanced, in the context of
> line level audio leads.  Unbalanced tends to be standard RCA audio
> interconnects and balanced tends to be CAT5E.
>
> May I ask what the difference is please?  When would you use one
> rather the other? How do you convert from on to the other?  I
> uderstand why it's easier to wire the house with CAT5E, and why the
> twisted pair maintains signal purity, but why wouldn't you send
> unbalanced through CAT5E?
>
> Thanks
>
> TBB


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