Operating instructions

23THE OUTLAW’S GUIDE TO THE SMS-1
We will start with the peak at around 32Hz. Peaks can be very problem-
atic acoustically. They can not only sound “boomy,” but they can also
eectively mask sounds at nearby frequencies – literally overpowering
those adjacent octave bands. Fortunately, pulling down those peaks
with the SMS-1 is a pretty straightforward task. Applying equalization to
pull down a peak actually lessens the burden on the subwoofer over that
frequency range, so we do not have to concern ourselves with creating
a situation that might create unintended stresses on the sub. For this
particular case, the peak is not very extreme so fairly little eort is needed.
We will use the third EQ channel, which defaults to 32Hz. We will adjust
all three settings for this channel, so we have to press “SELECT” on the
remote to gain access to all three adjustments. We’ll move the frequency
slightly, to 31Hz. We will adjust the level to -4.5dB. Because the peak
is small, we will increase the Q to 5.6 to decrease the range over which
the EQ acts. The System Response curve below shows you how these
changes attened out the peak at 32Hz.
The curve to the left still shows a dip around 52Hz, which is the next thing
we want to work on. “Pulling up” the curve at a dip requires the SMS-1’s
equalizers to boost the subwoofer signal at specic frequencies, and in
doing that we need to set aside our Outlaw natures and work a bit cau-
tiously. The biggest danger we want to avoid is “stacking” EQ’s. As we’ve
said before, stacking refers to placing two EQ channels at or very close to
the same frequency and then applying several dB of boost to both chan
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nels. This sounds like a great way to pull a deep dip up to a level response.
Unfortunately, it is also a great way to push a signicantly boosted signal
to the subwoofer. Assume for the moment that we have two EQ channels
set 2Hz apart (one at 24Hz and one at 26Hz) with the Q for both left at
the default and with +5dB of adjustment applied to both channels. This
is a classic example of stacking: both channels are going to overlap over
the entire 20Hz to 30Hz range, creating a combined signal boost of 10dB
across the middle portion of that range. That 10dB of boost is exactly the
same as removing the SMS-1 from your system and turning your system
up to 10dB above reference level (+10dB on the volume control, if your
receiver or processor uses the common volume scale of -70dB to +10dB).
Doing that with an aggressive DVD soundtrack will do all sorts of unpleas-
ant things to your hearing and your home’s foundations, but it will also
place your speakers at great risk for damage during the most energetic
soundtrack passages. Stacking EQ’s and applying a signicant boost to
those EQ’s does exactly the same thing over a very short frequency range,
but since the overall system volume isn’t pushed to deafening levels you
could easily not realize it was happening until your subwoofer broke.
Are you scared yet? You really don’t need to be – you just need to be a bit
deliberate about how you address dips in the frequency response. In this
case, we will try to use a single EQ set at the center of the dip and experi
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ment with a lowered Q value to allow a single EQ channel to take care of
the dip. With that in mind, our rst step will be to move the fth EQ from
50Hz to 51Hz, leave the Q alone at 4.3, and apply 5.0dB of boost. The Sys-
tem Response curve below shows the results of this rst attempt.