Proficient Protege F5 Series Owner's Manual page 8

Not Enough Bass in a 7.1 or 5.1 Surround System (Continued)
• Check that the receiver's calibration procedure is correctly adjusted. Usually, the receiver will send a test
tone through all the speakers in your system, allowing you to adjust (trim) the volume of each channel until
they are all playing at the same level.
• If the bass is weak only when playing 7.1 or 5.1 surround sources, check that your receiver is correctly set to
decode the 7.1 or 5.1 surround modes, such as Dolby Digital or DTS.
• Some DVD discs have a menu which allows you to select which soundtrack to play. Check that the correct
7.1 or 5.1 surround audio soundtrack is selected, otherwise it may just play stereo into your receiver and
you won't get the true LFE signal into the subwoofer.
Hum
Adding any component such as a subwoofer to an existing system will often give rise to a hum that wasn't
there before. Your first thought may be that the subwoofer has a problem, but this is more than likely caused
by a "ground-loop" in your system.
Follow these steps to isolate the main cause of the ground-loop hum (there may even be more than one
cause):
• Try to have all of your equipment on the same electrical outlet or circuit, provided that the total current
draw does not exceed the current safety rating of the outlet or circuit.
• If your subwoofer is a fair distance away from your other equipment, you may use a 15 amp extension cord
as long as it has a ground connection. NOTE: Never remove the ground pin from any power cords. This is
very dangerous.
• Turn off all components in your system, including the subwoofer, amplifiers, preamp and the receiver,
before disconnecting or connecting cables.
• First remove every connection from the subwoofer to the rest of your system. Plug the subwoofer power
cord back in and check for the hum. If it is still there, try plugging it into a different outlet in case it is
picking up interference on the AC line.
• If you have followed the above guidelines for the power connections and a hum is still present, then there
is one very common problem to consider: a "ground-loop" introduced by connecting a cable or satellite
feed to a DVR, Cable Box or Satellite Receiver or TV, which is then connected to the preamp. This can be
addressed as follows:
• Disconnect all cables that 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 your receiver, 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.
• If the hum persists, disconnect all the source components one at a time from the back of the receiver
until you identify the problem.
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