Setting the lfm’s controls, The scattered subwoofer system (two lfm’s) – Outlaw Audio LFM-2 User Manual

Page 8

background image


Outlaw Audio

Owner’s Manual

Setting the LFM’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.
If the actual +/- 3dB point cannot be obtained from the speakers’ specifications
or the manufacturer’s web site, you can use the following chart as a guideline:

40 Hz

Large tower speaker with one 12 or 15-inch woofer or two 10-inch
Small tower speaker with one 10-inch woofer or two 8-inch woofers

0 Hz

Small tower or large bookshelf speaker with one 8-inch or two 6-inch

80 Hz

Bookshelf speaker with one 6-inch or two 5-inch woofers

100 Hz Bookshelf speaker with one 5-inch woofer or two 4-inch woofers
10 Hz Satellite speaker with one 4-inch woofer or one or two

3.5-inch woofer(s)

Phase Switch

Depending on the absolute phase of your main speakers and amplifier, as well as
the relative distance from the LFM Subwoofer and main speakers to the listening
position, the bass in the crossover region may be smoother if you reverse the phase
of the LFM. Try both positions of the phase switch to determine which way sounds
more bass-heavy. The bass-heavier position is the setting where the output of the
LFM and the main speakers are most in phase. Use program materials with bass
in the crossover region such as music containing bass drums, double basses, bass
guitar, etc. to determine the correct setting.

Volume Level

Using the built-in test tones of your receiver/processor, match the levels of all of
your speakers including your LFM Series Subwoofer as described in your receiver
or processor’s owner’s manual. A setting of 5 on the LFM’s volume knob should
provide enough gain to properly match the sub level to your speakers. We recom-
mend using an SPL meter such as the Radio Shack model (part number 33-2050).
When using the test tones, measure from the listening chair and set the meter to
the 75 dB level. In order to accurately measure levels between channels use “C”
weighting and the “slow“ setting.
Note that the Radio Shack meter is down about 12 dB at 16 Hz, 7 dB at 20 Hz,
and 4 dB at 25 Hz. Add these numbers to the readout to compensate for these
errors if necessary.


: The Scattered Subwoofer System

(Two LFM’s)

Why Two Subwoofers?

In most circumstances two subwoofers will perform better than one. While you
might assume this is for added SPL, the greatest benefit will actually be smoother
bass response.
Room shape, the cubic volume of the room (width x depth x height), furniture,
floor coverings and even wall and ceiling material all play a roll in bass per-
formance. These factors create peaks and dips in the level of low frequencies at
different points in the room. That said, two properly positioned subwoofers will
distribute the bass throughout the room with greater accuracy than a single sub.
For this reason, many professional acousticians and installers recommend more
than one subwoofer. The final result is that you will create a much larger “sweet
spot” where the bass is powerful but more importantly smooth and consistent. If
near perfect bass response is your goal, consider using two LFM Series Subwoofers:
The Outlaw Audio Scattered Subwoofer Systems.

What’s Needed to Connect Two Subwoofers?

Most of today’s digital receivers and preamp/processors provide a single subwoofer
output. Connecting two subwoofers to these systems is as simple as adding a
Y-adapter. A Y-adapter splits a single output into two separate outputs. Be sure to
use a Y-adapter that is of equal or better quality than the subwoofer cables you
intend to use. (We recommend the Outlaw Audio PCA Y-Adapter.)
To use the Y-adapter, insert the single male end of the cable to the subwoofer
output of your receiver or processor. On the opposite end of the Y-adapter you will
now have two separate subwoofer outputs, one for each sub.

Placement and Level Control

Placement and level control of two subwoofers is somewhat more complicated
than using a single subwoofer. However, the end result of two properly placed and
calibrated subwoofers is well worth the added effort.
The procedure for placement of the second subwoofer is identical to that of de-
termining the placement of the first subwoofer (see the “Subwoofer Placement”
section of this manual). However, the second sub should be placed in the seating
area outside of the “sweet spot” where good bass response is also required. Walk
around the room until you find the area where the bass sounds the best, just as
described in the process for locating a single sub. This spot will almost always be
different than the one that was best for the primary sub.

NOTE: When calibrating your second subwoofer, be sure to turn off the first
sub. This will help you to determine ideal placement without being mislead
by the response of the first sub.

When calibrating the final levels of each subwoofer, you may want to reduce
their output to compensate for the added 3 or 4 dB of gain created by using two
subwoofers together.
If you sense a loss of bass output after properly locating and calibrating both
units in a two-subwoofer system, the likely problem is that the two units are out
of phase with each other. If this occurs try flipping the phase switch on the back
of one or both of the subwoofers until the bass returns. For more information
regarding the phase control function, please read the “Setting the LFM’s Controls”
section of this manual.

Setting the LFM’s Controls

This manual is related to the following products: