Hawkins Bass Control
-
Theory and Use
(302)
Hawkins Bass Control (variable) is a unique subwoofer control circuit in-
cluded with the Soundstream
RUBICON
amplifiers. It is capable of re-
moving subsonic energy in program material below 45 Hz
at 12 dB/Octave, while boosting subwoofer frequencies. The
circuit consists of two controls. One engages a subsonic
I
IllIll
High Pass filter at 45 Hz, and the other adjusts the amount
SUB
HAWKINS
SONIC
l BASS
of boost from 0 to
+9
dB.
CONTROL
The Boost control adjusts the amount of level applied at
the set frequency, and is adjustable from 0 to
+9
dB
(see
HAWKINS
BASS
CONTROL
.
figure 2). When the boost is set to 0, Hawkins Bass Control
acts as a sub sonic filter only. The simple act of removing
0
;I
9’
potentially harmful low frequencies can improve system
out-
.dB
Q
put by as much as 3
dB.
Application
I
FIG. 1
Subwoofer drivers in general have excel-
10
lent power handling characteristics over
5
their operational bandwidth. This band-
_i
width is determined by many factors, in-
dB_10
eluding
driver design, and enclosure type.
-15
It is possible to overdrive any subwoofer
-20
driver by sending powerful signals outside
of its operational bandwidth. These
po-
::z,,
Frequency
(Hz)
50
100
200
tentially damaging signals can be removed
FIG. 2 VARIABLE BOOST
by adding a subsonic filter. Figure 3 shows the effectiveness of the Hawkins
Bass Control on woofer excursion in a vented enclosure. The woofer travels
7.5 mm at 10 Hz. With Hawkins Bass Control properly adjusted, this excur-
sion can be reduced to less than 1 mm. This is of great benefit to lowering
woofer distortion and increasing output.
Adjustment
An easy method of optimizing your existing subwoofer enclosure with
Hawkin’s Bass Control is as follows:
1. Adjust the boost control to full
counter clock-wise (0) position.
2. Set the bass control switch to
“HAWKINS BASS CONTROL”.
3.
Play moderate to loud bass mate-
rial.
FIG. 3 Limited Excursion
4.
Adjust the boost (Q) control until
you reach the desired level.
11
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