Notes On “Hum”
With the growing sophistication of home theater systems, the potential for ground loops is enormous. Do not automatically assume that one or more of your components are at fault, or even defective. Lately, one of the biggest culprits is the
Almost 100% of the cases where hum has been a problem have been due to one or more of the below conditions. The following notes will help you to determine its cause:
Note 1:
Cable TV systems can sometimes contribute to ground loop problems which cause hum. To determine if your cable system is the contributing factor, disconnect the Cable TV incoming signal line (round 75 Ohm) at the wall, or the first component the cable is connected to (i.e. the cable box, or VCR). If the hum is no longer present, you must insert a 75 Ohm Ground Loop Isolator before reconnecting the line. You should check with your ATI dealer to obtain one. If the 75 Ohm Ground Loop Isolator works only partially, or not at all, then please read Note 2, Note 3 and Note 4.
Note 2:
Turn the system off and disconnect all inputs from the amplifier. If the hum persists, consult with your dealer or ATI directly. If the hum disappears, try another set of input cables. Connect one cable at a time to see if one specific cable is responsible. If any or all cables cause the hum to appear, then your preamp or processor should be evaluated for proper operation.
Note 3:
When there is an audible “hum” through your loudspeakers, even with the volume control low or off, you have a common problem known as a “ground loop”. A “ground loop” is basically a difference in ground voltages between two or more components which are connected electrically and which creates multiple current paths where there should be only one. This difference in potential causes a
WARNING: DO NOT, UNDER ANY CIRCUMSTANCES LIFT THE GROUND (eliminate the round, 3rd prong)
FROM THE PLUG USED WITH THE
Note 4:
Hum may also be caused by faulty
If the hum still persists after you have tried ALL of the above, please contact your dealer or ATI’s Service Department.
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