SVS PB12-ISD, Owner'S Manual

Page: 9 / 16

SV Subwoofers
Page 9
Parametric Equalizer (PB12-Ultra and select PB12-Plus subs only)
.
Important enough and challenging enough, this feature gets its own section! “PEQ” al-
lows 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 until it stops on “ MIN ” — thus ensuring you do not inadvertently
cause poor frequency response until such time as you properly configure the PEQ.
F
irst 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 al-
lows the user to manipulate the input signal so the acoustical output is more desirable for
their environment, in many cases allowing the worst peak to be “flattened”. By manipu-
lating the input signal with your PEQ you can cut a wide or narrow peak in response lo-
cated 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.
M
easure the room’s response
.
As indicated above, you must have a firm under-
standing of your room’s acoustical properties before you use a PEQ. To determine your
room’s natural response properties (and your subwoofer, in that room) you will need an
SPL meter shown 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 response 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 Re sponse
81
84
87
90
93
96
20 40 60 80 100
Fr e que nc y
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