ALLEN & HEATH XONE:96, Руководство пользователя

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ALLEN & HEATH
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AP11645_1_XONE:96 User Guide
The connection to earth (ground) in an audio system is important for two reasons:
SAFETY - To protect the operator from high voltage electric shock, and
AUDIO PERFORMANCE - To minimise the effect of earth (ground) loops which result in
audible Hum and buzz, and to shield the audio signals from interference.
For safety it is important that all equipment earths are connected to mains earth so that exposed metal parts are
prevented from carrying high voltage which can injure or even kill the operator.
It is recommended that a qualified system engineer check the continuity of the safety earth from all points in the
system including microphone bodies, turntable chassis, equipment cases, and so on.
The same earth is also used to shield audio cables from external interference such as the hum fields associated
with power transformers, lighting dimmer buzz, and computer radiation. Problems arise when the signal sees
more than one path to mains earth. An ‘earth loop’ (ground loop) results causing current to flow between the
different earth paths. This condition is usually detected as a mains frequency audible hum or buzz.
To ensure safe and trouble-free operation we recommend the following:
Have your mains system checked by a qualified electrician. If the supply earthing is solid to start with you are
less likely to experience problems.
DO NOT remove the earth connection from the console mains plug. The console chassis is connected to
mains earth through the power cable to ensure your safety. Audio 0V is connected to the console chassis
internally. If problems are encountered with earth loops operate the audio ‘ground lift’ switches on connected
equipment accordingly, or disconnect the cable screens at one end, usually at the destination.
Make sure that turntables are correctly earthed. A chassis earth terminal is provided on the console rear panel
to connect to turntable earth straps.
Use low impedance sources such as microphones and line level equipment rated at 200 ohms or less to
reduce susceptibility to interference. The console outputs are designed to operate at very low impedance to
minimise interference problems.
Use balanced connections for microphones and mix output as these provide further immunity by cancelling
out interference that may be picked up on long cable runs. To connect an unbalanced source to a balanced
console input, link the cold input (XLR pin 3 or jack ring) to 0V earth (XLR pin 1 or jack sleeve) at the console.
To connect a balanced XLR output to unbalanced equipment, link the cold output to 0V earth at the console.
Use superior quality cables and connectors and check for correct wiring and reliable solder joints. Allow
sufficient cable loop to prevent damage through stretching.
If you are not sure ...
Please contact your local Allen & Heath service agent or distributor for advice: www.allen-heath.com
EARTHING