HIGH PASS FILTER
This control sets the low frequency roll-off point of the amplifier, and is an important feature in maintaining
control over the extreme low end, especially under high drive conditions. This precision four pole filter is comprised of two cascaded
two pole filters, one fixed with a turnover frequency that is set at approximately 22Hz and a second variable filter that is variable
such that the overall low frequency roll-off can be adjusted from 30Hz to 150Hz. While HPF’s have been standard fare within the
pro audio industry for decades, this feature has only appeared in bass guitar amplifiers within the past few years (with a few notable
exceptions). This filter also provides additional mechanical protection to the speakers being used with the amp by limiting the power
to the speaker below the frequency range that the speaker cabinet cannot provide adequate acoustic loading to the drivers. This is
one of the primary (and preventable) causes of premature speaker failure, especially with compact speaker cabinet products that are
driven very hard. Another valuable use for this filter is to roll off the very low end when overdriving the amp. This prevents the signal
from becoming muddy, and preserves the naturally musical growl and grit of the overdriven signal. Experimentation will be helpful in
such applications..
VOICING CONTROL
This active EQ control modifies the amplifier’s response from a more flat like curve (in the counter-
clockwise position) to a more vintage curve (in the clockwise position) by modifying and shifting the frequency response in all regions
with a simple turn of the knob. As the control is rotated clockwise, the low end increases and the high end increases while the midrange
decreases and shifts upward. Common uses for the more vintage positions are the old school funk and slap tones, and rock tones where
a rounder bottom and a little bite are needed. Experimentation is an important part of discovering the potential of this powerful tool.
BASS CONTROL
This active EQ control is responsible for the amount of low frequencies present in the signal, relative to the
rest of the spectrum. Low frequencies (<80Hz) are responsible for the “bottom”, “roundness”, or “feel” of the tone. This is an active
control with boost and cut, the amount of boost proportional to the clockwise rotation to the right of “flat” (12:00 straight up) position
and the amount of cut proportional to the counter-clockwise rotation to the left of “flat” (12:00 straight up) position. As with everything
related to EQ, generally, a little bit goes a long way. Use enough to get the job done and no more. Note that if you have very compact
cabinets and need high volumes, you will want to be aware that it is possible to overdrive speakers with excessive bass boost. If
your speaker is not getting you enough high level low end, it’s also possible that you do not have enough “rig for the gig”, and “more
speaker” is needed. This is a shelving style filter.
LOW MID GAIN CONTROL
This control is responsible for the amount (or volume) of low midrange frequencies present in the
signal, relative to the rest of the spectrum. Low mid frequencies (the actual center frequency is selected with the low mid frequency
control) are responsible for the “earthy”, “woody” character of the tone. This is an active control with boost and cut, the amount of
boost proportional to the clockwise rotation to the right of “flat” (12:00 straight up) position and the amount of cut proportional to the
counter-clockwise rotation to the left of “flat” (12:00 straight up) position. This is a peak-dip (or bell) style filter.
LOW MID FREQUENCY CONTROL
This control is responsible for selecting the center frequency (or pitch) that the low mid
gain control acts on. Rotating this control sweeps the center frequency from lower (counterclockwise) to higher (clockwise). If the low
mid gain control is set at 12:00 noon, there will be no effect by the low mid frequency control because there is no boost or cut being
performed. Sweep range is from 150Hz - 1800Hz.
HIGH MID GAIN CONTROL
This control is responsible for the amount (or volume) of high midrange frequencies present
in the signal, relative to the rest of the spectrum. High mid frequencies (the actual center frequency is selected with the high mid fre-
quency control) are responsible for the “boxy”, “barky” character of the tone. This is an active control with boost and cut, the amount
of boost proportional to the clockwise rotation to the right of “flat” (12:00 straight up) position and the amount of cut proportional to
the counter-clockwise rotation to the left of “flat” (12:00 straight up) position. This is a peak-dip (or bell) style filter.
HIGH MID FREQUENCY CONTROL
This control is responsible for selecting the center frequency (or pitch) that the high
mid gain control acts on. Rotating this control sweeps the center frequency from lower (counterclockwise) to higher (clockwise). If
the high mid gain control is set at 12:00 noon, there will be no effect by the high mid frequency control because there is no boost or
cut being performed. Sweep range is from 300Hz - 5000Hz.
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