GAIN
CLIP
MIN MAX
(Hz)
10
50
SUBSONIC
(Hz)
50
500
LPF
5V/
20V
10V/
40V
NAR WIDE
(dB)
0
12
BOOST
WIDTH
(Hz)
30
80
FREQ
PARAMETRIC EQ
Top Panel Controls
Input Sensitivity Range:
Two input
Œ
sensitivity ranges are provided for each
channel pair to optimize source volume
range while minimizing the gain required
to achieve full power output for best signal-to-noise. Choose the input range that will
accommodate the source's maximum output signal voltage without excessive clipping, 5V or
10V for low level (RCA) inputs, and 20V or 40V for speaker level inputs.
Gain Adjustment with Clip LED:
This adjustment is for matching the amplifier's input to the
source's maximum undistorted output signal. The clip LED will dimly illuminate just before the
onset of clipping and become fully bright when the amplifier has reached full power output at
clipping. Follow proper gain setting procedure to ensure optimum source volume range with
minimum chance for clipping or distortion. Gain readjustment may be necessary after any
changes made to the parametric EQ, subsonic or low-pass filters.
Parametric EQ
: This section provides full adjustment over all parameters of a single EQ band,
Ž
including boost, width and frequency. Unlike traditional bass boost, a parametric EQ provides
the tuning flexibility required for differences between vehicles, subwoofers and enclosures.
Boost:
This adjustment sets the amount of boost
at the center frequency (Fc) of the parametric EQ
band from 0dB up to +12dB. Note that adding
boost may cause the output to clip or subwoofer
to be over-driven. Readjust the gain, subsonic and
low-pass filters as necessary to optimize bass
response vs. maximum output and volume range.
Width:
Also known as Q, width sets the
bandwidth (BW) of boost for the parametric EQ
band. A wide setting will include more adjacent
frequencies for a broad boost, while a narrow
setting will only boost frequencies close to the
chosen center frequency (Fc). The range of Q
adjustment is 1.5 (wide) to 5 (narrow). To calculate the bandwidth between the -3dB points
that are boosted by the EQ band, use the formula BW = Fc/Q.
Example: If FREQ is set to 50Hz, and WIDTH is set to narrow (Q=5), then the boosted
ð
bandwidth is 50Hz/5=10Hz, which puts the upper and lower -3dB points at 45Hz and 55Hz.
Frequency:
This adjustment sets the center frequency (Fc) of the parametric EQ band
‘
between 30Hz and 80Hz. Note that boosted frequencies that overlap with the subsonic and
low-pass filters will attenuated.
Subsonic Filter:
This adjustment sets the -3dB cut-off point ( ) below which all frequencies
’
F
3
are filtered out at -24dB/oct. Very low frequencies can waste amplifier power and damage
subwoofers. This adjustment is especially important for ported enclosures to prevent over-
excursion below the tuning frequency.
Low-Pass Filter:
This adjustment sets the -3dB cut-off point ( ) above which all frequencies
“
F
3
are filtered out at -24dB/oct. Unwanted high frequencies allowed to play through subwoofers
can cause boomy, buzzy bass that is easy to localize. With a steep -24dB per octave slope, the
cut-off frequency can be set higher, allowing more punch with less distortion and optimized
integration with full-range speakers to achieve up-front bass.
3
Œ
Ž
‘
’
Boost (
dB
)
Freq (Hz)
Fc
BW = F
2
-F
1
F
2
F
1
3dB
Note
:
If the subsonic and low-pass filter cut-off points are set too close together, only a narrow
frequency range will pass through and may result in significantly reduced output.
“
