Wisdom Audio DCAB-1 - Manual (Page 34)

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the bass at that frequency, and the reflection gets bigger along with the primary
sound. Either way, a positive and a negative add up to zero. This is less of a
problem at higher frequencies, where the waves are smaller and more easily dif-
fused in the room; but below perhaps 200 Hz, it can be a significant problem.
Thus if you start adding boost to a dip in your room and very little seems to
be happening, experiment by moving the microphone a couple feet (or half a
meter). If the response jumps back up, you have discovered a null. The solution
is to move either the speakers or the listening position, or to add effective low
frequency room treatment. (We told you that equalization would not solve all
your problems, as essential as it is.)
Remember that adding more power to a room null (a zone of cancellation) will
not help matters, and may in fact make the sound worse. If you find yourself
adding a lot of boost and not seeing or hearing much change, move the micro-
phone a couple feet to see if your position is in a null.
Next, use the notch filters in the low pass section of the DCAB-1 to address the
biggest peaks between 40 Hz and the crossover frequency. It is not unusual for
rooms to introduce errors of as much as 20 decibels in low frequency response.
(This fact is why we included the section on Room Acoustics in this manual.)
Fine-Tune Bassis By now, things should be looking pretty good. In most rooms, there will be still
a bit of a bump between 40-50 Hz (approximately), and then a some roll off
below that bump. Bassis can fix both problems.
Bassis Hz Adjustment The first step is to fine-tune the bassis frequency adjustment to correspond with
the frequency of the peak that occurs just above the roll off. You can always
fine-tune this at any time, but do the best you can now. It will usually be be-
tween 40-50 Hz on Adrenaline systems, in most domestic rooms.
Bassis Boost The bassis boost adjustment is expressed on a scale on 0-100, though (as dis-
cussed previously) this scale is not as linear as the percentage seems to suggest.
Most of its effect occurs between 0-20, with diminishing returns thereafter.
Take the bassis boost control up from 10 to 15%, so you can begin to see the
effect in the deep bass.
Qb to 55% Make sure the Qb control is set to 55%.
Once all calibration is complete, you will use the Qb control to make the
system either a bit leaner (lower value) or a bit more full (higher value) in the
bass. For the purposes of calibration, the best balance is 55%.
Qs to Counter the Peak Finally, vary the Qs control down to bring the peak around the bassis Hz adjust-
ment down. The Qs controls the width of the response dip that is designed to
counteract the speaker’s peak in the 40-50 Hz region. (Remember, Qs addresses