Balanced Cable Line Out

The signal wires pass an identical audio signal through each wire while the surrounding ground wire works the same as in unbalanced cables shielding the signal wires from external electronic interference.

Balanced cable line out.

Unbalanced line level connections are usually implemented with rca jacks for audio while balanced line level connections typically utilize dual 3 pin xlr jacks for both the input and output. Two signal wires and a ground wire. For an unamplified telephone line a twisted pair cable could only manage a maximum distance of 30 km. Two signals wires plus a separate ground wire.

However this did not become widespread until repeater amplifiers became available. In balanced signal paths there is a second signal conductor referred to as the cold line. As the signal voltage in the hot line increases the cold line s signal voltage decreases precisely mirroring the hot signal in reverse. Balanced cables have three wires inside the plastic casing.

A balanced cable by contrast has three conductors in the connector and three wires in the cable. The cable construction used for balanced telephone cables was twisted pair. The hot and cold lines transmit identical signals that are 180 degrees out of phase with each other. Balanced cables cost a lot more than unbalanced cables sometimes even twice as much simply because of the added benefit they provide.

In both cases one jack is normally used for each audio channel left and right. But what makes a balanced cable special is the way the gear utilizes that.