Subwoofer placement – Outlaw Audio LFM-1Plus User Manual

Page 7

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Variable Tuning LFM Series Low Frequency Modules

Owner’s Manual

Setting the Variable Tuning LFM Series Subwoofer’s Controls

Connecting to a System with No Preamp Outputs

If no low-level subwoofer output is available, you will need to run speaker wires
from your main amplifier or receiver to the subwoofer amplifier. See Diagram 2
on page 6.

To connect a Variable Tuning LFM Series Subwoofer using
high level inputs:

1. Turn off all system components and unplug the receiver and/or amplifier

and the LFM from their AC power source.

2. Locate the front left/right speaker output terminals on your receiver or


In cases where there are both “A” and “B” terminals, the “A” terminals should
be used. Disconnect any wire that is presently connected to these terminals.

3. Using the same type of speaker wire used for your other speaker

connections, connect the left and right channel speaker outputs of

your receiver or amplifier to the LFM’s High Level Inputs.

Be sure to connect the speaker wires to the appropriate input binding
posts on the back of the LFM, making certain that the polarity (–/+) on
the receiver or amplifier matches the polarity on the binding posts of the
subwoofer amp. In most cases this means connecting the red terminal
on the receiver or amplifier to the red terminal on the LFM, but always
check the markings on the rear panel to insure “+ to +” and “– to –”
connections. Also, make sure that the negative outputs on your main amp
are true ground; otherwise you would short the output of your main amp.
Call or email tech support if the negative outputs on your main amplifier
do not have true ground.

4. Connect the speaker wires to the high-level output terminals on the

back of the LFM Series Subwoofer.

Make certain that the polarity (–/+) on the subwoofer's high-level output
terminals match the polarity on the binding posts of the speakers. Also,
be sure to prevent any positive and negative strands of speaker wire from

5. Plug the LFM’s power cord into the input on the LFM Series Subwoofer

and connect the plug to an un-switched AC outlet.
CAUTION: Due to the power requirements of the LFM Series Subwoof-
ers, they must not be connected to the accessory outlets on a receiver
or processor. If a power-strip or surge protector is used, make certain
that it is rated to accommodate the LFM’s power requirements.

6. Reconnect your receiver and/or amplifier to the AC power source.

7. Proceed to the “Setting The LFM’s Controls” section to learn about the

LFM’s controls and how they operate.

Subwoofer Placement

Placement of your LFM series subwoofer is a critical component in maximiz-
ing its performance. The subwoofer's specific location in a room influences its
“perceived” frequency response, sound pressure level (SPL), and overall accuracy.
Since each listening room differs in virtually every aspect, the ideal location will
also vary.

An easy way to find the right spot to place your new Variable Tuning LFM Series
Subwoofer is to experiment with what we call the “Subwoofer Switch Trick.” This
process puts the subwoofer where you normally sit and then lets you play the role
of the subwoofer.
First, place the subwoofer as close to your favorite listening position as possible. This
should be directly in front of your couch or easy chair, right in the room’s “sweet
spot.” Provided that there is no damage to your furniture, you may even place the
subwoofer on the chair or couch, but remember that LFM Series Subwoofers are
heavy, and the Outlaws are not responsible for any damage to your furniture or
for arguments this might cause with other members of the household!
Second, activate the test tone from your processor or receiver’s internal test
tone generator, or use your favorite test disc so that pink noise plays through
the subwoofer. While the test tone is playing, walk around your room and find
the spots where you hear the best bass response. Sometimes this may be in the
center of the room, while in other cases you may find the best spot in a corner
or along a sidewall.
Finally, turn off the test tone and move the subwoofer to the location where you
hear the best bass response. If that location is unacceptable or impractical, repeat
the procedure to the spot that is the best compromise between bass performance
and aesthetic considerations.

Notes On Subwoofer Placement

Try to avoid creating a listening position that falls directly between the front
and back walls. This may cause a strong interference effect due to the collision
between bass waves bouncing off the rear wall and new waves emanating from
the LFM. When this happens you might hear an unnatural “build up” in the low
frequencies where the bass sounds “bloated”, based on the specific dimensions of
the room and the particular frequency being reproduced.
In other situations you might encounter a “null”, which is caused by two low fre-
quency waves canceling each other out. When this happens you will find that your
favorite listening position is bass shy. In this type of placement situation, bass response
will suffer greatly regardless of how powerful the subwoofer is. The best way to solve
this problem is to change the location of the seating position so that the distance to
the front of the room is different than that to the back of the room.

Setting the Variable Tuning LFM Series

Subwoofer's Controls

Variable Crossover

By adjusting the variable crossover on the LFM, you can perfectly match your LFM
Series Subwoofer to your main speakers. If your receiver or processor already has
a built in crossover, disable the crossover on the LFM by flipping the “X-OVER”
switch to the “BYPASS” position. Refer to the owner’s manual for your receiver
or processor to see how to disable any internal crossover capability it may have.
If your receiver or processor does not have internal crossover control, follow these
steps to set LFM’s variable crossover:
Determine the +/- 3dB point of your main speakers. This frequency is usually
found on the speaker’s specifications sheet or may often be available on the
speaker manufacturer’s web site. Start with the crossover set approximately to
this point. By experimenting with the crossover frequency and level control, you
can fine-tune the LFM Series Subwoofer so that there is a seamless link between
the LFM and the main speakers.

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