louder (at your listening position) than the de-
sired response. Using the three dials shown in
figure 5.1, the UFW-12’s parametric equalizer will
allow you to flatten up to 1 peak in your room,
thus giving you the flattest (most natural) overall
response.
In order to find out exactly how your room is af-
fecting your UFW-12 Subwoofer, you need to
perform a “frequency sweep” of your room. This
will give you a graphical representation of how
the UFW-12 is performing in your unique listen-
ing environment.
5.1 Performing a Room Frequency Sweep
Though there are a number of ways to perform
an accurate frequency sweep, we’ve detailed the
steps involved in the most basic method below.
a. Sit in your favorite seat and hold your Ra-
dio Shack SPL meter at a 45-degree angle
half way between horizontal and vertical.
b. The meter should be placed at ear level
when seated in the primary listening posi-
tion, and is best if supported by a station-
ary object such as an end table or tripod.
c. Assuming you have already calibrated all
channels to reference level, set your sub’s
volume to 70dB.
d. Play a 25Hz track from a test tone CD,
such as "Rives Audio Test CD 2" available
through www.rivesaudio.com
,
and record
BOTH the frequency (your x-axis), which
corresponds to the track on the test disc,
and the SPL (your y-axis) as shown on
the meter.
e. Next, play the tracks from 25Hz to 120Hz
and record the SPL for each frequency
played.
f.
Important Note: The Radio Shack sound meter
uses C-weighting for its readout. This compen-
sates for the inaccuracies of the human ear at
low frequencies. We want to measure the actual
response. As a result, a correction key is needed
to ensure proper response before your final
measurements are plotted. We suggest gather-
ing the data using the readings on the meter and
then correcting your results with the compensa-
tion coefficients shown in figure 6.1 (at the end
of this manual).
5.2 Interpreting the Results
Once you’ve completed this exercise, you will
have a data list much like that shown in figure
5.2 below (though much more detailed and com-
plete).
Now that you have a complete data set derived
from YOUR room, you need to plot this response
visually, either in MS Excel or simply on graph
paper (a computer application is recommended
to smooth the curve) to obtain a graphical repre-
sentation of your room’s effect on the UFW-12.
An example, derived from figure 5.2 above, is
shown on the following page in figure 5.3.
Note the relative flatness of the overall response
as well as the magnitude of your largest peak.
Some nulls are likely to be present, however fill-
ing in a null or dip with any EQ is not likely to be
effective, and the power required can make such
an attempt undesirable. If desired or necessary,
you may wish to try moving the sub to a new
location for a flatter response. Sometimes only a
Frequency
(Hz)
Gain (dB)
20
64
25
67
32
70
40
71
55
74
63
71
80
72
100
70
Figure 5.1
Figure 5.2
