GMC 2005 Envoy Owner's Manual page 212

Setting the Tone (Bass/Treble)
AUDIO: Push and release the AUDIO knob until BASS,
®
MID (without Bose ), or TREB appears on the display.
Turn the knob to increase or to decrease. The
display will show the bass, midrange (without Bose
or the treble level. If a station is weak or noisy, decrease
the treble.
To adjust the bass, midrange (without Bose
treble to the middle position while it is displayed,
push and hold the AUDIO knob. The radio will produce
one beep.
To adjust all tone and speaker controls to the middle
position, push and hold the AUDIO knob when no tone
or speaker control is 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.
To return the bass and treble to the manual mode,
push and release the AUTO EQ button until CUSTOM
appears on the display.
If the radio is equipped with the Bose audio system, the
equalization settings are either CUSTOM or TALK.
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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 the rear
speakers, push and release the AUDIO knob until FADE
®
), or the appears on the display. Turn the knob to move the
sound toward the front or the rear speakers.
To adjust the balance or the fade to the middle position
while it is displayed, push the AUDIO knob, and hold
it until you hear one beep.
To adjust all tone and speaker controls to the middle
position, push and hold the AUDIO knob when no tone
or speaker control is displayed. ALL CENTERED will
appear on the display and you will hear a beep.