Soundstream Technologies 604 - Manual (Page 7)

Hawkins Bass Control Theory and Use
The and 604 amplifiers incorporates an on-board stag-
gered electronic crossover, with full range RCA outputs to drive an external
amplifier. No external electronic crossover is necessary. The high and low
pass portions of the crossover can be set independently of one another.
In many car audio installations, there is a tendency for a boom.”
Because of their interior dimensions, most cars will resonate or ring at these
frequencies. If we design the system so there is reduced ouput in
this region, the final response is very smooth and natural sounding. The
high pass crossover is independently variable from 65 to 220 Hz at 12
Octave, and low pass crossover is independently variable from 30 to 120 Hz
at 24
(12 on
For initial crossover setup, try setting the low pass filter to approximately
60 Hz, and the high pass filter to approximately 100 Hz. Change the cross-
over points to accommodate a good mixture of frequency response, power
handling, and personal preference.
12 High Pass
Hawkins Bass Control (variable) is a unique subwoofer control
circuit included with the Soundstream and 604 am-
plifier. It is capable of removing subsonic energy in program ma-
terial below 45 Hz at 12 while boosting subwoofer
frequencies. 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 The Hawkins Bass Control func-
tions on either pair of channels or if their low pass filter
is engaged.
The Boost control adjusts the amount of level applied at the set
SON C l
CONTROL
HAWKINS
CONTROL
FIG. 1
frequency, and is adjustable from 0 to (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 frequencies I O
can improve system output by as much as 3
NOTE: The RUBlCON204 contains
Hawkins Bass Control which is
similiar to the variable version except the
boost is fixed at
Application -25 .
Subwoofer drivers in general have excellent Frequency (Hz) 5 0 100 2 0 0
power handling characteristics over their FIG. 2 VARIABLE BOOST
tional bandwidth. This bandwidth is determined by many factors, including driver
design, and enclosure type. It is possible to overdrive any subwoofer driver by
sending powerful signals outside of its operational bandwidth. These potentially
damaging signals can be removed 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 excursion 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
Bass
Control is as follows:
1.
2.
3.
4.
Adjust the boost control to full counter
clock-wise (0) position.
-15
Set the bass control switch to “HAWKINS
BASS
CONTROL”.
Frequency (Hz) 5 0 100 2 0 0
Play moderate to loud bass material.
FIG. 3 Limited Excursion
Adjust the boost (Q) control until you reach the desired level.
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.
12 13