Soundstream Technologies 204, 604, 404 owner manual Hawkins Bass Control Theory and Use

Hawkins Bass Control - Theory and Use

The RUBICON204,404 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 “midbassboom.” Because of their interior dimensions, most cars will resonate or ring at these midbass frequencies. If we design the system so there is reduced ouput in this region, the final response is very smooth and natural sounding. The

Hawkins Bass Control (variable) is a unique subwoofer control

circuit included with the Soundstream RUBICON and 604 am- plifier. It is capable of removing subsonic energy in program ma- terial below 45 Hz at 12 dB/Octave, 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 +9 dB). The Hawkins Bass Control func- tions on either pair of channels (l&2 or 38~4) if their low pass filter is engaged.

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HANKINS

SUB • BASS

SON C CONTROL

HAWKINS

BASS

CONTROL

0’06

.dB

Q

high pass crossover is independently variable from 65 to 220 Hz at 12 dB/ Octave, and low pass crossover is independently variable from 30 to 120 Hz at 24 dB/Octave. (12 dB/Octave lowpass on RUBICON204)

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 dB/Octave High Pass

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The Boost control adjusts the amount of level applied at the set								FIG. 1
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 frequencies I O
can improve system output by as much as 3	5
dB. NOTE: The RUBlCON204 contains	O
Hawkins Bass Control (rixecj) which is dB -5
similiar to the variable version except the 1::
boost is fixed at +6dB.	-20,
			-	. -	I		I
Application	-25	_	I
		L
Subwoofer drivers in general have excellent -3010			Frequency (Hz)			5 0		1 0 0	2 0 0
			FIG. 2 VARIABLE BOOST
power handling characteristics over their opera-
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 Hawkin’s Bass lo Control is as follows:

1.Adjust the boost control to full counter ds_ji

clock-wise (0) position. - 15

2.Set the bass control switch to “HAWKINS -20

BASS CONTROL”.	:,2,5;
	Frequency (Hz)5 0	1 0 02 0 0

3. Play moderate to loud bass material.

FIG. 3 Limited Excursion

4.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.

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