INSTALLATION STEP 7
THEORY AND USE
LSE.Q
is a proprietary subwoofer control circuit included with the
amplifier. lt
is capable of both removing subsonic energy in program material and providing a variable
boost at low frequencies. The circuit consists of two controls. One adjusts the frequency
of operation, and the other adjusts the range of boost. With both controls adjusted fully
counter-clockwise, no boost is applied and the amplifier is flat in response down to 20 Hz.
FIG.
1
The frequency control (Hz)
adjusts the starting point of the subsonic filter. This high
pass filter can be adjusted from 20 Hz up to a maximum of 60 Hz. This control is useful
for setting the lowest frequency that your subwoofer will see. (See Figure 1)
The control
adjusts the amount of boost applied at the set frequency.
This is adjustable from
(flat) to 2.8
(See Figure 2)
0
When the is set to
(Butterworth),
acts as a subsonic filter
only. (See Figure 3)
-15
-20
The simple act of removing the signal below the vented tuning frequency
can improve system output by as much as 3
With Q values greater
Frequency (Hz)
100
200
than
boost is added in addition to the subsonic filter. (See Figure
4)
FIG. 2 Variable
Application
Woofers in vented enclosures have good power handling characteristics
above the tuning frequency, but below the tuning frequency, power handling
drops off considerably. This is due to the loss of any appreciable resistive
FIG, 5 Limited Excursion
should remove these unwanted signals by adding the subsonic filter. Figure
5 shows the effectiveness of
on woofer excursion. Woofer travel is 7.5
mm at 10 Hz, with
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
“Hz” control is as follows.
air mass.
At frequencies below
resonance, the woofer starts to
behave as if it were mounted in “free-
100
air”.
If we wish to improve the
FIG. 3
Variable
High
Pass
performance of a vented system, we
Adjust frequency and boost control to full CCW position.
2.
While listening to music with strong bass content at a moderate level,
slowly adjust the frequency control clockwise. Listen for a reduction of
bass response. Now, rotate frequency control slightly backwards. This
the purpose of removing the “subsonic” bass energy.
Frequency (Hz)
FIG. 4 Variable “Q”
Soundstream’s LSE.Q contains the same type of circuit with the added
benefit of infinite adjustability. Our “Q” and “Hz” control can provide virtually any combination of boost and cut to suit
your designs. So, LSE.Q can provide the “tailoring” needed for any type of “assisted” design and any woofer.
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