About Equalization
The Hartke Systems Model 3500 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. 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 Model 3500 provides you with two different means for equalizing your bass sound: � Low Pass and High Pass Contour controls provide 18 dB of cut or boost in two broad frequency bands. A Graphic Equalizer provides 15 dB of cut or boost in ten narrow frequency bands.
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CONTOUR
3 5 0 3 5 5 10 10 15 -18 15 +18 15 -18 3 0 3 5 10 15 +18
Normally, you will adjust the two Contour controls before �fine-tuning� your EQ with the Graphic Equalizer. The Low Pass Contour control affects a broad band of frequencies with 100 Hz as the center point; similarly, the High Pass Contour control affects a broad band of frequencies with 10 kHz as the center point. When either 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 cut (�attenuated�). Because there is very little bass guitar energy at 10 kHz, the High Pass Contour control should be thought of as your overall �noise� control�turning it down (to the left of the �0� position) will help to eradicate hiss and buzz while having very little effect on the bass guitar signal. Similarly, the Low Pass Contour control, when set left of 0, can be used to eliminate rumble and �woofiness.� The ten-band graphic equalizer provides ten sliders, each corresponding to a single narrow frequency band (at 30 Hz, 64 Hz, 125 Hz, 250 Hz, 500 Hz, 1 kHz, 2 kHz, 3 kHz, 5 kHz, and 8 kHz). This allows you to �draw� the desired tonal response of your system. When a slider is in its center detented position (�0�), it is having no effect. When it is moved above center (towards �+15�), the particular frequency area is being boosted; when it is moved below center (towards �-15�), the frequency area is being attenuated. We carefully selected these frequency areas because they have maximum impact on bass signals. For example, the lowest slider (30 Hz) affects the very lowest audible frequencies (in fact, most humans cannot hear below 20 Hz), while the highest four sliders (2, 3, 5, and 8 kHz) affects the �twang� of a bass string.
LOW PASS
HIGH PASS
Contour controls
GRAPHIC EQUALIZER
30Hz +15 64Hz 125Hz 250Hz 500Hz 1KHz 2KHz 3KHz 5KHz 8KHz +15 +12 +9 +6 +3 +2 -2 -3 -6 -9 -12 -15
IN
0
OUT
-15
30Hz
64Hz
125Hz
250Hz
500Hz
1KHz
2KHz
3KHz
5KHz
8KHz
Graphic equalizer
WARNING: Use caution when raising the 30 Hz slider above 0 if you are operating at high volume levels (especially if Compression is not being used) since this can place undue stress on connected loudspeakers.
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