Hartke AC75 Owner's Manual

Contents

Hartke AC75 Owner's Manual Manual pdf 18 page image

14About EqualizationThe Hartke AC75 or AC150 Acoustic ampli-fier gives you enormous control over shapingthe sound of your acoustic rig, using a pro-cess called equalization. To understand howthis works, it’s important to know that everynaturally occurring sound consists of a broadrange of pitches, or frequencies, combinedtogether in a unique way. This blend is whatgives every sound its distinctive tonal color. EQcontrols allow you to alter a sound by boostingor attenuating specific frequency areas—theyoperate much like the bass and treble controlson your hi-fi amp, but with much greater preci-sion. The AC75 or AC150 provides you with onemost effective tool for shaping the overall toneof your Acoustic sound; a Graphic Equalizerproviding 12 dB of cut or boost in five narrowfrequency bands.The five-band graphic equalizer providesseven sliders, each corresponding to a singlenarrow frequency band (100Hz, 315Hz, 1kHz,3.5kHz and 10kHz.). This allows you to “draw”the desired tonal response of your system.When a slider is in its center position (“0”), ithas no effect. When it is moved above center(towards “+12”), the particular frequency area isbeing boosted; when it is moved below center(towards “-12”), the frequency area is beingattenuated. We carefully selected these frequen-cy areas because they have maximum impacton acoustic signals. For example, the lowestslider (100 Hz) affects the very lowest audiblefrequencies (in fact, most humans cannot hearbelow 20 Hz), while the highest four slidersaffects the mid-range and high frequencies.To find out how each graphic equalizer slideraffects the sound of your particular acoustic,start with all five bands flat (that is, all five slid-ers at their “0” center position).