Lexicon DD-8 - Manual (Page 14)

DD-8 Power Amplifiers
Operation Manual 14
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A humming sound is present in the audio.
Audible hum, or a discernable low frequency noise is one of the most common problems within
audio/video systems. This problem, even when the volume is at a low level, Is usually caused by a
common problem known as a “ground loop”. A ground loop occurs when there is a difference in
ground voltages between two or more components that are connected electrically.
In most cases, one or more of the following suggestions below will solve the hum problem.
1. If a cable TV connection is present, disconnect the cable for the wall outlet. If this
eliminates the humming sound, a ground loop isolation device is required. Contact your
dealer or cable provider for assistance.
2. Disconnect components one at a time to isolate the problem. Once the problem is
identified, make sure the associated component is properly grounded and connected to
the same electrical ground as the DD-8 amplifier.
3. Turn off all components within your system and then disconnect the input cables on the
DD-8 amplifier. Turn the amplifier back on. If the hum disappears the fault may be with
the input cables that are being used. Make sure the cables are properly shielded or use
a cable that has better shielding. Make sure the cable is not running or laying on top of
any AC power cords.
4. Ground loop problems may also be caused by poor grounding of the electrical system
within your home or may be caused by faulty earth grounds in your home’s electrical
system. To isolate the problem, try unplugging components with three prong grounded
power cords one at a time to see if one or all are causing the problem. In the past, cold
water pipes and other utilities were often used for grounds. These items may not be
still valid because of corrosion of the existing pipes and the installation and use of PVC
piping. Please check with a licensed electrician for further evaluation.
If all else fails…
1. Contact an authorized Lexicon dealer.
2. Contact Lexicon Customer Technical Support at 888-691-4171.
Maintenance
Routine maintenance should be performed on a periodic basis. Clean the exterior surfaces of the
unit with a soft, dry, lint-free cloth. Do not use alcohol, benzene, acetone-based cleaners, or strong
commercial cleaners. Do not use a cloth made with steel wool or metal polish. If the unit is exposed to
a dusty environment, a low-pressure blower may be used to remove dust from its exterior.