2005 GMC Safari Owner's Manual - Page 154

Setting the Tone (Bass/Treble) BASS: Slide this lever up or down to increase or to decrease bass. TREB (Treble): Slide this lever up or down to increase or to decrease treble. If a station is weak or noisy, decrease the treble. Radio with CD Adjusting the Speakers (Balance/Fade) BAL (Balance): Turn the control ring behind the upper knob to move the sound toward the left or the right speakers. FADE: Turn the control ring behind the lower knob to move the sound toward the front or the rear speakers. 3-44