Maintaining Audio Quality in the Broadcast Facility 2011 - Orban

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through the terminating BNC connectors.
Audio/IP
Maintaining Audio Quality
Networked audio connections follow the same exact wiring convention as all other
Ethernet data networks. Category 5, 5e, or 6 Ethernet cable should be used.
Headroom
The single most common cause of distorted broadcast/netcast sound is probably clipping—intentional
(in the audio processing chain) or unintentional (in the program
chain). In order to achieve the maximum benefit from processing, there must be no
clipping before the processor! The gain and overload point of every electronic component
in the station must therefore be critically reviewed to make sure they are
not causing clipping distortion or excessive noise.
In media with limited dynamic range (like magnetic tape), small amounts of peak
clipping introduced to achieve optimal signal-to-noise ratio are acceptable. Nevertheless,
there is no excuse for any clipping at all in the purely electronic part of the
signal path, since good design readily achieves low noise and wide dynamic range.
Check the following components of a typical audio facility for operating level and
headroom:
� Analog-to-digital converters
� Studio-to-transmitter link (land-line, microwave, or optical fiber)
� Microphone preamps
� Console summing amplifiers
� Line amplifiers in consoles, tape recorders, etc.
� Distribution amplifiers (if used)
� Signal processing devices (such as equalizers)
� Specialized communications devices (including remote broadcast links and
telephone interface devices)
� Phono preamps
� Tape and cart preamps
� Record amplifiers in tape machines
� Computer sound cards
VU meters are worthless for checking peak levels. Even peak program meters (PPMs)
are insufficiently fast to indicate clipping of momentary peaks because their integration
time is 5 or 10ms, depending on which variant of the PPM standard is employed.
While PPMs are excellent for monitoring operating levels where small