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Hi. Because we offer both subwoofers and power amplifiers that have XLR or balanced
cable connections, we often get the question from our customers,
"Well, should I use that XLR, that balanced connection,
or should I just use the RCA connection?" Now, balanced cables were really developed
for uses where you have long, long runs. Thousands of feet of cable.
Like think about if you have wiring in a stadium or in a concert venue.
They are also used in recording studios where noise is a huge issue and they also
have long runs with very small signals, like from microphones for instance.
So should I care? Should you even bother with that in your home system?
Well, I like to use balanced connections where they are available in certain
applications and I'll run down exactly why. So first of all,
what we have to understand is that balanced connections,
just like RCA connections, you need to use the same connection
on both ends. There is absolutely no point in connecting an XLR on one end and having
an RCA on the other. You get zero benefit from the balanced
connection because internally, all that's happened is that one of the
connections with a balanced connector isn't going anywhere.
So there is no point in doing that. Save your money because balanced
connections and cables usually are a little bit more expensive.
So assuming you do have two components that have XLR connectors on both ends,
should you use that connection? Well, if you can afford the additional cost,
there are benefits. The difference between a balanced connection in audio equipment
is usually something that's run, what we call differentially.
Now, I'm sorry I'm going to get into some sciency stuff for one second.
So in a typical RCA connection, there are two contacts or two conductors.
You have the center pin and then you have the outer pin.
The outer pin is always the ground but that ground in a two-wire system
like an RCA is also the return. What it means is that we need a
complete loop, a complete circle for an electric connection to be made and
to flow. So what happens is that that ground connector is not a
dedicated connector. It's part of the signal loop.
In a balanced connection, you have a positive and a negative
connector inside the XLR that are, in a differential system,
they're running out of phase to one another. So they're inverted
to one another. Now, I haven't said anything about ground.
Now, the ground in an XLR connector is made up of both shield and pin one,
it's called. But those things are separate to the electronics that are driving
positive and negative pins out that XLR connector. So why does that matter?
Well, at the receiving end, so let's say your amplifier or
your subwoofer, there's going to be something called a differential amplifier.
That amplifier will only respond or amplify signals that are different
between the two pins. Because the two signals are out of phase
in an XLR connector, it means that when, let's say a sine wave signal moves,
that when there's a peak and a valley that correspond at the same time,
it's going to amplify that difference. But if we have a noise signal,
and that noise can be coming from anywhere. It can be radiated from the air,
it can be interference from other electrical equipment,
it will appear in the same phase on those two conductors. And so,
when the difference amplifier looks at those two noise signals,
they're exactly the same and they're cancelled out. So what you end up having
is you have a conductor and connector that's much more immune to any sort
or form of noise. But also note, again, I didn't say anything about the signals
traveling on the shield or the ground connector. That's because in an XLR or a
balanced system, that doesn't happen. So, if you ever run into a ground loop, and
they are easy, easy in home theater systems, because typically,
your subwoofer is going to be located far away from your equipment rack and probably
on a different AC circuit in your house through a different breaker,
that sets up a potential for a very, very good and nasty-sounding ground loop.
If you use now a balanced connector in place of an RCA, an XLR connector,
it will break that ground loop. So for things like subwoofers where you
have a longer cable run and ground loops are very possible, I always recommend XLR.
Unfortunately, a balanced subwoofer output is only normally found on the highest end,
and hence, most expensive home theater receivers and processors.
But if you have it, use it. If you don't, don't worry about it. In most cases,
there's other solutions if you have a ground loop and, you know what?
We're talking about those really noisy environments like living next to a
cellphone tower that are really going to make a big difference between the two
cable types. So don't lose sleep if you only have RCA. Thank you.