Yamaha EM5014C User Manual download pdf (Page 13)

Making the Most of Your Mixer

EMX5014C Owner’s Manual

Mixer Basics

Balanced, Unbalanced—What’s the Difference?

In a word: “noise.” The whole point of balanced lines is noise

rejection, and it’s something they’re very good at. Any length of wire

will act as an antenna to pick up the random electromagnetic

radiation we’re constantly surrounded by: radio and TV signals as

well as spurious electromagnetic noise generated by power lines,

motors, electric appliances, computer monitors, and a variety of other

sources. The longer the wire, the more noise it is likely to pick up.

That’s why balanced lines are the best choice for long cable runs. If

your “studio” is basically confined to your desktop and all connections

are no more than a meter or two in length, then unbalanced lines are

fine—unless you’re surrounded by extremely high levels of

electromagnetic noise. Another place balanced lines are almost

always used is in microphone cables. The reason for this is that the

output signal from most microphones is very small, so even a tiny

amount of noise will be relatively large, and will be amplified to an

alarming degree in the mixer’s high-gain head amplifier.

How Do Balanced Lines Reject Noise?

** Skip this section if technical details make you queasy. **

Balanced lines work on the principle of “phase cancellation”: if you add two identical signals out of phase (i.e.

one signal is inverted so its peaks coincide with the troughs in the other signal), the result is … nothing. A flat

line. The signals cancel each other out.

While the desired audio signals in the hot and cold conductors are out of phase, any noise induced in the line

will be exactly the same in both conductors, and thus in phase. The trick is that the phase of one signal is

reversed at the receiving end of the line so that the desired audio signals become in-phase, and the induced

noise suddenly finds itself out of phase. The out-of-phase noise signal is effectively canceled while the audio

signal is left intact. Clever, eh?

To summarize

Microphones: Use balanced lines.

Short line-level

runs:

Unbalanced lines

are fine if you’re in a

relatively noise-free

environment.

Long line-level

runs:

The ambient

electromagnetic

noise level will be

the ultimate

deciding factor, but

balanced is best.

Hot (+)

Cold (–)

Ground

Balanced noise cancellation

Unbalanced noise

Noise

Source Cable Receiving device

Source Cable

Phase

inversion

Noise

Noise-free

signal

Phase

inversion

Receiving device

Noise cancelled

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Yamaha EM5014C User Manual Page 13

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