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Using Equalization
The Hartke Systems A 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 A 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 A 25 and A35 offer four bands of equalization. Each EQ knob (labeled Bass, Mid, Treble
and Bright, respectively) affects a different frequency area (100 Hz, 830 Hz, 5 kHz and 8
kHz, respectively) and provides approximately 15 db of boost and attenuation except for
the Bright control which provides 0 -20 dB of Boost only. We carefully selected these fre-
quency areas because they have maximum impact on bass signals. For example, the
Bass (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.
BRIGHTTREBLEMIDBASS
-12
-9
-6
-3
0
+3
+6
+9
+12
-15 +15
100Hz
-12
-9
-6
-3
0
+3
+6
+9
+12
-15 +15
830Hz
-12
-9
-6
-3
0
+3
+6
+9
+12
-15 +15
5K 8K
0
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