Hsu Research Subwoofer STF - Manual (Page 6)

• You are not using the power cord that came with the
subwoofer. Switch to a non-grounded IEC power cable
or use a 3 to 2 non grounded cheater plug. This will
remove ground loop issues.
• A very common ground loop source is cable TV or
satellite cabling. Very few installers take the time to
ground the cable to the house ground, causing a 60 Hz
hum that the subwoofer reproduces. Disconnect the
coaxial cable from your TV or VCR. If the hum goes
away, the cable is the cause. In that case you can get
an inexpensive 75 ohm ground loop isolator from
Radio Shack or your local electronics store. Ground
loops can also come from faulty electrical wiring in your
home. Consult a licensed electrician to evaluate and
possibly repair the AC wiring in your home.
• Disconnect all interconnects from the amplifier. If still
hums, call or email technical support.
• It is possible that some cables have a poor or broken
ground due to poor construction, oxidation, or damage.
Also, poorly shielded cables can potentially pick up
noise. Try another interconnect or speaker wire. Also,
move the signal cable away from AC cables, power
transformers, or other EMI sources.
• Use an AC line filter or plug the unit into a different circuit.
• If hum goes away when interconnects are disconnected,
the hum is coming from the rest of your equipment.
Add them back one piece at a time. The one that causes
the system to hum is the source of the hum.
• The unit is going into STANDBY mode during the quiet
passages. Try turning the source signal up. On a Dolby
Digital receiver, turn the SUBWOOFER level up in the
SPEAKER SET-UP menu. After you turn the signal up, turn
down the volume knob on the subwoofer to compensate.
• An alternative is to turn the subwoofer ON/AUTO/OFF
switch to the ON position. It does not use any more
power and does not affect reliability.
Troubleshooting
If you think your subwoofer has a problem, please do everything you can to confirm the problem before calling for service, including
reading through the troubleshooting section. Many times the problem actually is caused by other items in the system or the subwoofer’s
interaction with those items. Much of the time, the service department will not be able to reproduce the error.
Problem Cause Solution
Humming or
buzzing noise
Subwoofer goes into
STANDBY mode
while material
is playing.
You have a ground loop. This causes the
vast majority of hum related complaints.
The electrical grounds of the components
in your system are not at the same elec-
trical potential.
You have an amplifier problem.
Your speaker wires or interconnects are
the cause.
A light dimmer or other triac based (SRC)
device is on the same AC circuit.
You have a problem with other equipment.
The source is not providing enough signal.
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