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Page 9
Parametric Equalizer. Important enough and challenging enough, this
feature gets its own section! “PEQ” allows you to tame a “peak” in your room’s
response. Peaks are quite common, especially in large rooms or ones where your sub
is far from your listening position. NOTE: A Sound Pressure Level meter is a must
for proper use of the PEQ, so get one before you tackle this control. TO DISABLE
THIS CONTROL: Set the “LEVEL” control in the Parametric EQ feature group-
ing until it stops on “MIN” — thus ensuring you do not inadvertently cause poor
frequency response until such time as you properly configure the PEQ.
First you might ask yourself, “why use a PEQ?” The reason is quite simple. Your
room. See, most times even a superlative subwoofer which measures very evenly
(we say “flat”) in an open domain (no reflective boundaries) will not measure the
same in your home theater or music room. Instead, colliding bass waves can build up
and cause a “peak”. This is where a parametric equalizer helps out. A PEQ is an
electronic circuit which allows the user to manipulate the input signal so the acousti-
cal output is more desirable for their environment, in many cases allowing the worst
peak to be “flattened”. By manipulating the input signal with your PEQ you can cut
a wide or narrow peak in response located somewhere in the frequency range of the
equalizer. Importantly, the equalizer found your sub only allows reduction of peaks,
and is “cut only”, not a boost device.
Measure the room’s response. As indicated above, you must have a firm
understanding of your room’s acoustical properties before you proceed with use of a
PEQ. To determine your room’s natural response properties (along with your sub-
woofer’s, in that room) you will need an SPL meter as described on Page 6, and at
least a pad of graph paper and a pencil for charting as below. If you have graphing
program similar to Microsoft Excel ® this will save some time graphing the re-
sponse curves. The last item to correctly measure the room’s response is a test disc
that can play specific frequencies. The disc should contain frequencies from 20Hz to
100Hz. One of the most popular frequency tests discs is Autosound 2000 CD #101.
It can be found at www.carsound.com/cds.shtml and is quite inexpensive.
Room A Response
81
84
87
90
93
96
20 40 60 80 100
Frequency
Freq 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100
SPL 85 84 86 91.5 95 90 84 84 86 86 85 83.5 83 83.5 84.5 85 86
Figure 3