Hum
Adding any component such as a sub-
woofer to
an
existing system
will
often give
rise to a hum which wasn't there before.
Your first thought may
be
that the sub-
woofer 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 ex-
ceed 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.
•
Turn off
all
components
in
your system,
including
the subwoofer, amplifiers and
the processor, 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 com-
mon problem to consider: a
"ground-loop"
introduced by connecting a cable TV
line
to a
VCR
or
TV,
which
is
then connected
to the preamp. This can be addressed as
follows:
•
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 your processor,
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 processor
until you iden-
tify the problem.
• If
you are using the subwoofer's
line-level
inputs and there is a excessive amount
of
noise or hum present, try using the
speaker-level
inputs as they may
yield a
lower background noise
level.
•
Ground-loop isolators are
available for
audio lines and video.
Once you have
identified which components are causing a
problem, you can fit the isolators between
the component and the preamp.
No
auto
turn
off
•
The subwoofer should turn itself off after
approximately fifteen minutes with no
audio signal present. If
not, check there is
no background hum. The subwoofer may
sense hum as a
small signal and stay on.
See
the above hints to eliminate the hum.
No
auto
turn
on
•
The subwoofer's volume control may
be
turned down, or no signal is received from
your processor.
• Check the input connections.
• Check
on surround systems to be certain
that a bass signal is being sent to the
subwoofer.
DECLARATION OF CONFORMITY,
ACCORDING TO
EN
45014
Manufacturer's
name:
Sunfire
Manufacturer's
address:
1300
E.
New
Circle
Rd.,
Suite 150,
Lexington,
KY USA
Declares
that
the
products
listed
on
this
declaration:
Product name(s):
Amplified subwoofer speaker
Product
Model
Number(s):
HRS-8,
HRS-10,
HRS-12
Conform
to
the
following
product
specifications:
Safety: IEC 60065:2001
JEN
60065:2002
EMC:
EN
55013:2001 +AI:2003+A2: 2006
EN
55020:2002
+ Al:2003
+
A2:2005
EN
61000-3-2:2000
+
A2:2005
EN
61000-3-3:1995
+
Al:2001 +A2:2005
The
product
hereinwith
complies
with
the
provisions
of
the
following
European
Directives
and
carries
the
CE
mark
accordingly:
Low
voltage
directive 73/231 EEC,
as
amended
Electromagnetic Compatibility Directive
89J3361 EEC, as amended
Supplementary
information:
The product was tested
in
a
typical
configuration
Signed:
Mark Weisenberg
General
Manager
Date
05/18/09
18
---+------------------------
SUJ?fire
User's
Manual
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