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Faultfinding Your R200i
Cause and
Elimination
of Hum
Hum is a particularly annoying form of noise in any high fidelity system
and at some time has been experienced by many of us.
Hum may result from a number of different situations and to make matters
worse maybe caused by a seemingly illogical combination of
circumstances.
One or more of three specific causes creates hum in the system.
Induced Hum
Hum can be induced into the system from one or more sources and is
generally associated with the radiation of noise from one system into
another.
Hum and noise can be radiated from any object or system involving AC
voltage and current such as power supplies in amplifiers, motors, switching
equipment etc. All of these may be found in your hi-fi system or within
your own home.
Hum may be induced into any part of the system, so there are no specific
instructions that can be given which will offer a guaranteed cure. A good
practice to adopt is to keep low-level signal equipment such as phono
systems, tuners etc. well away from high-level signal equipment such as
power amplifiers. Alternatively, careful designs must be employed to
negate these effects on low-level signal equipment (such as the R200i
onboard phono module option). Another good practice to adopt is to keep
all signal leads away from power leads.
The practice of neatly tying excess leads together for a tidy looking
installation should be resisted, as this could be the cause of induced hum in
the system.
Earth Loops
Earth loops are a particularly annoying cause of hum in the system. Earth
loops are created by mains frequency current flowing in the screen of
signal leads and becomes apparent with the lack of adequate earthing
between the various pieces of equipment making up the hi-fi system. This
is further compounded by the fact that the equipment earthing
considerations vary between different manufacturers and countries.
Perreaux products used with equipment manufactured by other
manufacturers may cause an earth loop situation, but Perreaux products
used with other Perreaux products will not cause an earth loop situation
provided the following precautions are observed:
