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10
Using Equalization and Shape
The Hartke Systems B Series Bass Amplifier gives you enormous control over shaping the
sound of your bass, using a process called equalization. To understand how this works,
it’s important to know that every naturally occurring sound consists of a broad range of
pitches, or
frequencies, combined together in a unique way. This blend is what gives every
sound its distinctive tonal color. The B Series EQ controls allow you to alter a sound by
boosting or attenuating specific frequency areas—they operate much like the bass and
treble controls on your hi-fi amp, but with much greater precision.
The B Series offers three bands of equalization. Each EQ knob (labeled
Low, Mid, and
High, respectively) affects a different frequency area (100 Hz, 300 Hz, and 5 kHz,
respectively) and provides approximately 15 db of boost and attenuation. We carefully
selected these frequency areas because they have maximum impact on bass signals.
For example, the Low (100 Hz) control affects the very lowest audible frequencies (in fact,
most humans cannot hear below 20 Hz), while the High (5 kHz) control affects the “twang”
of a bass string.
When an EQ knob is in its center detented position (“0”), it is having no effect. When it is
moved right of center, the particular frequency area is being boosted; when it is moved left
of center, the frequency area is being attenuated. Turning all EQ controls up the same
amount will have virtually the same effect as simply turning up the Volume; conversely,
turning them all down the same amount will have virtually the same effect as turning down
the Volume. Both approaches are pointless (after all, that’s why we gave you a Volume
control!)
In many instances, the best way to deal with equalization is to think in terms of which
frequency areas you need to attenuate, as opposed to which ones you need to boost.
Be aware that boosting a frequency area also has the effect of boosting the overall signal;
specifically, too much Low EQ boost can actually cause overload distortion or even harm
the connected speaker.
In addition, the B60, B90 and B120 models provide a unique Shape control which employs
a
notch filter to remove specific frequency areas. At the same time, it overlays a special
equalization curve that is designed to improve the sound of electric bass instruments.
This curve provides boost at certain frequency areas and attenuation at other frequency
areas. As the Shape knob is turned clockwise, the notch filter is imposed on higher
frequency areas; as it is turned counterclockwise, the filter is imposed on lower frequency
areas. At the fully clockwise position, the filter is applied to the 1 kHz frequency area,
making for a deep, rich tone; at the fully counterclockwise position, the filter is applied to
the 90 Hz frequency area, making for a bright, twangy tone.
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BASS MID HIGH
ENGLISH