Today's Lesson

Let's talk about the difference between balanced and unbalanced and what the advantages are of using these cable types. 

To begin, balanced cables consist of three wires, unlike unbalanced cables which only have two. In balances cables, you have the same signal and ground wires as with unbalanced, but the third cable carries a negative signal. This negative signal is the same as the regular or positive signal, except it is reversed in polarity. As the two signals travel along the cable, they actually cancel each other out. Why do we want them to cancel out, doesn’t that mean that the signal goes away? 

Well yes, but only while traveling across the cable. Once the two signals reach the end, the negative signal is reversed in polarity and both signals end up perfectly in phase. The benefit of this is that any interference that the cable might have picked up along the way is actually cancelled out when the negative signal is flipped. This is called common mode rejection. This allows balanced cables to be quiet over much longer runs and they also end up being a bit louder than their unbalanced counterparts. 

The two most common examples of balanced cables in live sound production are XLR cables and TRS quarter inch cables. You can tell the difference between TS and TRS by the number of small bands around the connector tip. Two bands equals TRS as these bands separate the tip, ring and sleeve, which are connected to the three wires within the cable. 

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