10About EqualizationCONTOUR03515-18351015+180351015-18351015+18LOW PASS HIGH PASSContour controlsINOUT+15+12+9+6+3+2-2-3-6-9-12-15+150-158KHz5KHz3KHz2KHz1KHz500Hz250Hz125Hz64Hz30Hz8KHz5KHz3KHz2KHz1KHz500Hz250Hz125Hz64Hz30HzGRAPHIC EQUALIZERGraphic equalizerThe Hartke Systems Model 3500 Bass Amplifier gives you enormous controlover shaping the sound of your bass, using a process called equalization. Tounderstand how this works, it’s important to know that every naturally occurringsound consists of a broad range of pitches, or frequencies, combined together ina 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 fre-quency areas—they operate much like the bass and treble controls on your hi-fiamp, but with much greater precision. The Model 3500 provides you with twodifferent means for equalizing your bass sound:• Low Pass and High Pass Contour controls provide 18 dB of cut or boostin two broad frequency bands.• A Graphic Equalizer provides 15 dB of cut or boost in ten narrow fre-quency bands.Normally, you will adjust the two Contour controls before “fine-tuning” your EQwith the Graphic Equalizer. The Low Pass Contour control affects a broad bandof frequencies with 100 Hz as the center point; similarly, the High Pass Contourcontrol 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 itis moved right of center, the particular frequency area is being boosted; when itis moved left of center, the frequency area is being cut (“attenuated”). Becausethere is very little bass guitar energy at 10 kHz, the High Pass Contour controlshould be thought of as your overall “noise” control—turning it down (to the leftof the “0” position) will help to eradicate hiss and buzz while having very littleeffect on the bass guitar signal. Similarly, the Low Pass Contour control, whenset left of 0, can be used to eliminate rumble and “woofiness.”The ten-band graphic equalizer provides ten sliders, each corresponding to asingle 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 tonalresponse 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 partic-ular frequency area is being boosted; when it is moved below center (towards“-15”), the frequency area is being attenuated. We carefully selected thesefrequency areas because they have maximum impact on bass signals. Forexample, 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.WARNING: Use caution when raising the 30 Hz slider above 0 if you areoperating at high volume levels (especially if Compression is not beingused) since this can place undue stress on connected loudspeakers.