When you are evaluating voltage and current requirements for your
audio system, it is important that your equalizer and/or audio system
does not exceed the capacity of your AC service. You should make
certain that the earth (green) wire for the AC system makes a reliable
earth connection, and determine as best as possible that the AC system
is free of noise that could generate unwanted audible sounds or cause
problems in microprocessor based equipment.
When using a larger rack system it is recommended that a dedicated
and isolated AC service be provided. This service should have its own
AC wires, isolated receptacle, and breaker and not be shared with other
unrelated equipment.
Even with an isolated AC system, it may still be necessary to make use
of surge protectors, line filters, isolation transformers, or all of the
above. Power conditioners should be selected with care, since they
sometimes generate undesirable switching noises in audio systems.
When connecting many pieces of electronic equipment to an AC system
it is important that the AC is properly distributed. It is better to connect
all plugs to a common AC source than to have AC receptacles in
different locations.
When installing a large audio system, it may be necessary to consult a
qualified electrician that is familiar with the specialized style of
electrical wiring required for recording studios.
Clock noise is one of the greatest enemies of the audio racks AC
system. If a computer or any microprocessor based device (most
samplers and effects are) emits or somehow couples its clock signal
with the neutral or earth of its own power cable, it will contaminate
your AC system and carry the clock noise into other equipment; almost
always with undesirable results.
The AC earth connection exists to protect you, your equipment and
possibly your building from an electrical disaster. In a properly wired
system, if a 120 volt AC wire were to break within your equipment's
chassis, it should make contact with the Safety Earth Wire that is
connected to the chassis, and blow the fuse or trip the circuit breaker
until the problem has been corrected. Given the same circumstances, if
the AC safety ground has been defeated with a ground lift or the AC
service is incorrectly wired, the equipment's chassis and quite possibly
everything attached in that rack would be “live” with 120 volts (220,
230, 240 in Europe)
AC Distribution
and Safety
Proper AC grounding
Quality AC system
AC distribution
Clock noise and AC
Safety earth connection
Chapter 4
Wiring and Other
20
