Owner's Manual and Installation Guide 5/3 Channel Power Amplifiers 255, 355, 555
Hawkins Bass Control
-
Theorv and Use
Hawkins Bass Control (variable) is a unique subwoofer control
circuit included with the Soundstream
RUBICON
amplifier. It
is capable of removing subsonic energy in program material be-
low 45 Hz at 12 dB/Octave, while boosting subwoofer frequen-
cies. The circuit consists of two controls. One engages a sub-
sonic High Pass filter at
45
Hz, and the other adjusts the
amount
of boost (0 to
+9
dB)
(fixed at
+6dB
for the
RUBCON
&
355).
The Boost control adjusts the amount of level applied at the
set
frequency, and is adjustable from 0 to
+9
dB
(see figure 2). When
the boost is set to 0, Hawkins Bass Control acts as a sub sonic
filter only. The simple act of removing potentially harmful low fre-
quencies can improve system output by as much as 3
dB.
Application
Subwoofer drivers in general have excel-
lo
lent power handling characteristics over
5
their operational bandwidth. This bandwidth
.t
is determined by many factors, including dB-l~
HAWKINS
BOCST
Q
.
0
c’
;
INSTALLATION STEP 1
SELECTING THE SPEAKER OUTPUT MODE
Channels 1 through 4 of the
RUBICON255,
355
&
555 amplifiers have the ability
to operate in any one of the following modes:
5CH (Stereo /Mixed Mono): Use this mode for 5 channel stereo operation (all
channels) or for Mixed Mono operation_
3CH
(Bridged
Mono): Use this mode to bridge channels l&2 and
3&4
outputs for
3 channel operation.
FIG,
1
Please follow the wiring schemes below for the correct operation:
driver design and enclosure type. It is pos-
15
I
!
I
sible to overdrive any subwoofer driver by
-*Or
f
t
sending powerful signals outside of its op-
-*’
!
I
I
. 1
!
erational bandwidth. These potentially dam-
-3010
1
:recuency
(HZI 50
100
260
aging signals can be removed by adding a
FIG. 2 VARIABLE BOOST
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 excursion can be reduced to less
than 1 mm. This is of great benefit to lowering woofer distortion and increasing
output.
Adjustment (555 on/y)
An easy method of optimizing your existing subwoofer enclosure with Hawkins
Bass Control is as follows:
10
c
1.
Adjust the boost control to full counter
0
clock-wise (0) position.
-5
dB
-10
2. Set the bass control switch to
,5
“HAWKINS BASS CONTROL”.
20.
3.
Play
moderate
to
loud bass
material.
-301 0
Frequancy
(Hz) 50 100 230
4.
Adjust the boost (Q) control until you
FIG. 3 Limited Excursion
reach the desired level.
,
hi
,;
1
.__
-
-rTl
\.
/’
5CH
1
.
‘\
/’
BRlDGi5-MoNO
..__
__,’
STEREO
-
L+
-
R+
-
L+
-R+
__~
____._-
__.____
/---------
---
---
--__
\
‘~
With Soundstream’s Hawkins Bass Control, the boost and frequency control can
provide the “tailoring” needed for any type of “assisted” design and any woofer in
any type of installation.
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