Emotiva DMC-1 - Manual (Page 88)

Page 88 Page 89
“Hum” Noises
This problem is more than likely caused by a “ground loop” in your system, rather than a fault in the
DMC-1. Follow these steps to isolate the main cause of the hum, there may even be more than one.
Remember to turn off all components in your system, including the DMC-1, before disconnecting
or connecting any cables.
Disconnect the following items in order, and check each time if the hum has gone away:
Disconnect all cables which come from outside the room, such as cable TV, satellite TV, or roof top
antennas. Make sure that they are disconnected where they first enter the room, so they are making no
connection to the DMC-1 or the TV, or any other component. If the hum is caused by the cable TV line,
then you will need a “ground loop isolator.” This is an inexpensive device fitted in line with the coaxial
cable feed. Contact your cable company or your Emotiva Dealer (unless purchased through AV123) for
assistance.
Disconnect all connections from the DMC-1 to your TV.
Disconnect any component which has a grounded power cord.
If the hum persists, disconnect all the source components one at a time from the back of the DMC-
1, until you identify the problem. (Ground loop isolators are available for audio lines and video. Ask
your Emotiva Dealer for assistance)
Try moving the speaker cables away from any power cords. Try just one speaker, connecting it to different
channels and see if an amplifier channel is bad.
If you are still having a problem, remember that Emotiva’s dealers and technical support staff will
assist you.
Other Probable Causes of Noise
Speaker noise may also be caused by interference or noise on your AC line. Make sure there are no
large appliances sharing the line, or halogen lamps or light-dimming Triac devices.
Try connecting your system to another AC socket on a separate line.
If the hum is heard from within the DMC-1 and not through the speakers, this may also be caused by
interference on the AC or DC lines. The power transformers may turn this interference into an audible
noise. Internal hum can be made worse by a shelf or cabinet resonating, so try moving the DMC-1 to
another shelf.
Try moving your components further away from the TV, especially if you ever notice the screen has changed
color in the area closest to the component.
If you have very high efficiency speakers, these may tend to reveal noises which other speakers do
not.