Audio Engineering

762 Chapter 27

27.2 Standard Levels and Level Meters ........................................................................

Suppose I asked you to put together a device comprising component parts I had
previously organized from different sources. And suppose I had paid very little attention
to whether each of the component parts would fi t together (perhaps one part might be
imperial and another metric). You would become frustrated pretty quickly because the
task would be impossible. So it would be too for the audio mixer, if the signals it received
were not, to some degree at least, standardized. The rationale behind these standards and
the tools used in achieving this degree of standardization are the subjects of the fi rst few
sections of this chapter.

The adoption of standardized studio levels (and of their associated lineup tones)
ensures the interconnectability of different equipment from different manufacturers and
ensures that tapes made in one studio are suitable for replay and/or rework in another.
Unfortunately, these “ standards ” have evolved over many years and some organizations
have made different decisions, which, in turn, have refl ected upon their choice of
operating level. National and industrial frontiers exist too, so that the subject of maximum
and alignment signal levels is fraught with complication.

Fundamentally, only two absolute levels exist in any electronic system, maximum level,
and noise fl oor. These are both illustrated in Figure 27.1. Any signal that is lower than
the noise fl oor will disappear as it is swamped by noise and signal, which is larger than
maximum level will be distorted. All well-recorded signals have to sit comfortably
between the “ devil ” of distortion and the “ deep blue sea ” of noise. Actually, that’s the
fundamental job of any recording engineer!

In principle, maximum level would make a good line-up level. Unfortunately, it would
also reproduce over loudspeakers as a very loud noise indeed and would therefore, likely

Maximum

signal level

Noise

floor

Figure 27.1 : System dynamic range.