Yamaha MG206c-USB Owner's Manual download pdf (Page 8)

MG206C/MG166CX/MG166C Owner’s Manual

Mixer Basics

Making the Most of Your Mixer

You’ve got yourself a mixer and now you’re ready to use it.

Just plug everything in, twiddle the controls, and away you go … right?

Well, if you’ve done this before you won’t have any problems, but if this is the first time you’ve

ever used a mixer you might want to read through this little tutorial and pick up a few basics

that will help you get better performance and make better mixes.

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 sur-

rounded 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 con-

ﬁned 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 micro-

phones 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.

Signal Levels and the Decibel

Let’s take a look at one of the most commonly used units in

audio: the decibel (dB). If the smallest sound that can be

heard by the human ear is given an arbitrary value of 1, then

the loudest sound that can be heard is approximately

1,000,000 (one million) times louder. That’s too many digits

to deal with for practical calculations, and so the more appro-

priate “decibel” (dB) unit was created for sound-related mea-

surements. In this system the difference between the softest

and loudest sounds that can be heard is 120 dB. This is a

non-linear scale, and a difference of 3 dB actually results in a

doubling or halving of the loudness.

You might encounter a number of different varieties of the

dB: dBu, dBV, dBM and others, but the dBu is the basic deci-

bel unit. In the case of dBu, “0 dBu” is speciﬁed as a signal

level of 0.775 volts. For example, if a microphone’s output

level is -40 dBu (0.00775 V), then to raise that level to 0 dBu

(0.775 V) in the mixer’s preamp stage requires that the signal

be ampliﬁed by 100 times.

A mixer may be required to handle signals at a wide range of

levels, and it is necessary match input and output levels as closely as possible. In most cases the “nominal” level

for a mixer’s input and outputs is marked on the panel or listed in the owner’s manual.

Hot (+)

Cold (–)

Ground

Source

Cable

Noise cancelled

Noise-free

signal

Phase

inversion

Receiving device

Phase

inversion

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 electromag-

netic noise level will be the

ultimate deciding factor, but

balanced is best.

Noise

Balanced noise cancellation

+ 20 dBu

0 dBu

0.775 V

20 dBu

40 dBu

60 dBu

The inputs and outputs on

home-use audio gear usually

have a nominal level of –7.8 dBu

(–10 dBV).

Most professional mixers,

power ampliﬁers, and other

types of equipment have inputs

and outputs with a nominal level

of +4 dBu.

Microphone signal levels vary

over a wide range depending on

the type of microphone and the

source. Average speech is

about –30 dBu, but the twitter-

ing of a bird might be lower than

–50 dBu while a solid bass

drum beat might produce a level

as high as 0 dBu.

1 2 3 4 5 6 7 8 9 10 11 12 13 ... 28 29

Comments to this Manuals

No comments

Yamaha MG206c-USB Owner's Manual Page 8

Comments to this Manuals

Related products and manuals for Audio mixers Yamaha MG206c-USB