GMC 2006 Sierra 1500 Pickup Owner's Manual page 281

Setting the Tone (Bass/Treble)
AUDIO: Push and release the AUDIO knob until BASS
or TREB appears on the display. Turn the knob to
increase or to decrease. The display will show the bass
or treble level. If a station is weak or noisy, decrease
the treble.
To adjust the bass or treble to the middle position while it
is displayed, push and hold the AUDIO knob. The radio
will produce one beep and adjust the display level to the
middle position.
To adjust all tone and speaker controls to the middle
position, push and hold the AUDIO knob when no tone or
speaker controls are displayed. ALL CENTERED will
appear on the display and you will hear a beep.
AUTO EQ (Automatic Equalization): Press this button
to select customized equalization settings designed
for country/western, jazz, talk, pop, rock, and classical.
The radio will save separate AUTO EQ settings for
each preset and source.
If the radio is equipped with the Bose
the equalization settings are either CUSTOM or TALK.
Adjusting the Speakers (Balance/Fade)
AUDIO: To adjust the balance between the right
and the left speakers, push and release the AUDIO
knob until BAL appears on the display. Turn the knob
to move the sound toward the right or the left speakers.
To adjust the fade between the front and rear
speakers, push and release the AUDIO knob until FAD
appears on the display. Turn the knob to move the
sound toward the front or the rear speakers.
To adjust the balance or fade to the middle position
while it is displayed, push and hold the AUDIO knob.
The radio will produce one beep and adjust the display
level to the middle position.
To adjust all tone and speaker controls to the middle
position, push and hold the AUDIO knob when no tone
or speaker controls are displayed. ALL CENTERED
will appear on the display and you will hear a beep.
®
audio system,
3-103