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User's Manual

18

Hum

Adding any component such as a

subwoofer to an existing system will
often give rise to a hum which 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, see
page 9 for more details.

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 and the preamplifier, 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 connect-
ing 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 preampli-
fier, 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 preamplifier until you
identify the problem.

If you are using the subwoofer’s Line

Level inputs and there is a excessive
amount of noise or hum present, using
the Speaker Level inputs 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 preamplifier.

The subwoofer won’t 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.

The subwoofer won’t turn on

The subwoofer’s volume control may be

turned down or no signal is received
from your preamplifier.

Check the input connections.

Check the mode switch on surround

systems to be certain that a bass signal
is being sent to the subwoofer.

Audible snap from outlet

When the subwoofer is initially plugged

into the wall, there is an in-rush current
surge as the power supply capacitors
charge up. This may give rise to an
audible snap from the outlet as the plug
is inserted. This can be avoided by
plugging the subwoofer into a switched
outlet or switched power strip (rated at
15 amps or more).

Содержание True Subwoofer Signature

Страница 1: ......

Страница 2: ...onnected to a power supply only of the type described in these operation instructions or as marked on the Component 9 Power Cord Protection Power supply cords should be routed so that they are not lik...

Страница 3: ...igurations 11 Adjusting the controls 15 Specifications 16 Troubleshooting guide 17 Limited warranty 19 Service assistance 19 Contents To find out more about this and other Sunfire products please visi...

Страница 4: ...ously variable volume level control Soft clipping circuit allows graceful overload and prevents speaker damage due to clipping Gold plated inputs and outputs Dear Friend Thank you for purchasing my Su...

Страница 5: ...hould position the driver with the bump towards a protected side The Amplifier The large movement range of the drivers creates greater air pressure inside the box than a conventional woofer Therefore...

Страница 6: ...pro duce frequencies up to 100 Hz With the control fully counter clockwise the subwoofer reproduces up to 30 Hz Rotate the control until the bass sounds natural If the mid bass sounds natural but you...

Страница 7: ...r a signal is present at the inputs of the subwoofer The high pass crossover is a passive network with a fixed crossover frequency of 70 Hz and a 6 dB per octave slope We recommend using this high pas...

Страница 8: ...g it to adhere solidly to the floor To move the woofer along the floor rotate it onto one edge and it will slide along easier Heat rise Allow adequate ventilation around the metal control panel of the...

Страница 9: ...uld be fully shielded and as short as possible for the job The longest cable in your system will likely be to the subwoofer so choose a good quality brand Some patch cords can be a very tight fit and...

Страница 10: ...bwoofer s performance Moving the subwoofer from one corner to another can have a major effect on the bass response Remember to keep it at least two or three feet away from any TV screen computer VCR o...

Страница 11: ...LFE output can be connected in the same way The subwoofer will play the low frequency range and the other speakers will play the frequency range delivered to them by your amplifier If you have a home...

Страница 12: ...R bass The opening scene in Top Gun for example has loads of L R bass information If this is not preserved the bass in these scenes sounds anemic The Sunfire Subwoofer utilizes differential gain on th...

Страница 13: ...e subwoofer s fixed high pass crossover point The signals coming out of the subwoofer s high pass outputs are not affected by any of the controls They are just a copy of the signals going in except th...

Страница 14: ...ction of your receiver s power is transferred to the subwoofer There is no need to use the Speaker Level inputs if you are using a separate amplifier and preamplifier Such systems are best connected u...

Страница 15: ...ill do fine as will the Stereophile test CD Step 1 Disconnect the subwoofer and run the main speaker with a tone in its passband 80 100Hz Measure the level Step 2 Disconnect the main speaker and recon...

Страница 16: ...ft input with volume control at 0dB 60 mVrms with volume control fully clockwise 0 75 Vrms from right input with volume control at 0dB 200 mVrms with volume control fully clockwise Input impedance 15...

Страница 17: ...r using a remote control or with a small volume knob on the back panel Make sure that this is adjusted correctly Check that your preamplifier or receiver s sub output is turned on Some systems only ha...

Страница 18: ...hat they are disconnected where they first enter the room so they are making no connection to your preampli fier TV or any other component If the hum is caused by the cable TV line then you will need...

Страница 19: ...y defective product and shall not in any event include property or any other incidental or consequential damages which may result from the failure of this product Some states do not allow limitations...

Страница 20: ...Manual part number 913 038 00 Rev A...

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