Alpine 3672 - Manual Adjustment Procedure

This display shows how many decibels of sound pressure
exist at each frequency. A pleasant sounding system should
have a smooth frequency response transition. Also, the rela-
tive balance between the different drivers’ output levels must
be correct.
Due to different component speaker efficiencies, power am-
plifier sensitivity, vehicle interior resonances, speaker and
speaker enclosure non-linearities or interior audio section
frequency response, an unadjusted system may have many
peaks and dips in its frequency response.
The 3672 can be adjusted to balance the acoustical response
and reduce other non-linearities.
Certain frequency regions can also be boosted or cut to
overcome road noise or to accommodate listener prefer-
ences.
4. If you are using a head unit with separate front and rear
pre-outs, verify that the 2-inout mode is selected, and fade
to the front. Make sure that the rear drivers are defeated.
Remember to keep the vehicle doors and windows closed
during adjustments.
5. Analyze the spectrum display on the RTA to detect any
imbalances between the output levels of each component
driver. For example, in the display shown, the
Subwoofer’s response is lower than the mid-bass driver
and the mid-bass driver’s response is lower than the
midrange speaker.
6. Find out which speaker's output is about average when
compared to the other bands. Try to keep that region’s
output level control at OdB as much as possible. It is
important to keep as many outputs as possible
around the 0dB mark. This is to avoid clipping or poor
signal-to-noise ratio problems common with excessive
boost or cut values. In the example shown above, the
mid-bass level is about average. Therefore the Sub-
woofers and High outputs must be boosted and the mid-
range output should be reduced.
7. While observing the RTA screen, adjust the output level
control to proper :shape and smooth out the level differ-
ences.
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8. Adjust and fine-tune the crossover points for each region
to further smooth out the acoustical response.
9. Adjust the Phase Switches for CH 1/2 Low and High or
CH 3/4 Mid and High (as applicable) to create the desired
imaging characteristics.
10. Adjust the Subwoofer Output Phase switch for the best
low frequency response.
11. If your head unit has a single pre-amp output only, skip to
item 14.
12. Fade to the rear, check for defeated front speakers, close
all vehicle doors and windows, and repeat steps 5 through
10.
13. Re-center the fader control, verify that all speakers are
functional, close all the vehicle doors and windows, and
repeat steps 5 through 10.
14. The Subwoofer output, CH 1/2 High or CH 3/4 High output
(or any other output) level can now be increased or
decreased for customer preferences such as more low
bass or more emphasized highs.
15. Using a high quality music source, carefully evaluate the
sound and perform any additional adjustments as neces-
sary.
NOTE: It is almost always necessary to dial-in additional
sub-bass boost in order to overcome road noise which
increases with the vehicle’s speed. If using the Alpine
4313 remote Subwoofer Level Control, adjustment in a
stationary car is sufficient. The bass output can he in-
creased or reduced by the user. Furthermore, the original
setting can also be restored by returning the control to
its center detente.
16. lf the 4313 Remote Subwoofer Level Contro! was not
installed, it will be necessary to test-drive the car, listen,
and set the 3672's Subwoofer level control to a compro-
mised value between the optimum setting for stationary
and freeway speed conditions.
ADJUSTMENT WITHOUT AN RTA:
1. The unit should be temporarily moved to the driver’s seat
vicinity using long extension cables, and the adjustment
should be done with the installer in the driver's seat.
2. Ahigh quality source material (music) with excellent sound
quality and frequency response must be used.
3. Turn the sound system on, verify that all components are
functional, and place all controls such as Bass, Treble,
Fader, Balance, in-dash equalizer controls (if any) and the
4313 Remote Subwoofer Level Control (if used) are in the
center detente (neutral) position. Also verify that the Input
Mode Switch, Subwoofer Fading Mode Switch, Subwoo-
fer Stereo/Mono Switch, and CH 1/2 and CH 3/4 Cross-
over Mode Switches are set as needed.
Perform the following steps while seated in the driver’s
seat, with all doors, windows and trunk closed, and the
vehicle interior completely intact.
4. If you are using a head unit with separate front and rear
pre-ouis, verify that the 2-Input mode is selected, and fade
to the front. Make sure that the rear drivers are defeated.
5. Listen carefully and try to find output level imbalance
between the different component speakers.
6. If such an imbalance exists, determine which output level
is average (higher than some and lower than some other
ones).
7. Try to keep the output level for that band (or bands) at OdB
if possible. ;
8. Boost or cut the other bands as necessary to balance the
sound.
9. Adjust and fine-tune the crossover points for each region
for the most smooth and pleasant sound.
10. Adjust the Phase Switches for the CH 1/2 Low and High
or CH 3/4 Mid and High outputs to create the desired
imaging characteristics.
11. Adjust the Subwoofer Output Phase Switch for the best
low frequency response.
12. If your head unit has a single pre-amp output only, skip to
item 15.
13. Fade to the rear, check for defeated front speakers, close .
all vehicle doors and windows, and repeat steps 5 through
11.
14. Re-center the fader control, verify that all speakers are
functional, close all the vehicle doors and windows, and
repeat steps 5 through 11.
15. The Subwoofer output, CH 1/2 High or CH 3/4 High output
(or any other output) level can now be increased or
decreased for listener preferences such as more low bass
or more emphasized highs.
16. Using a high quality music source, carefully evaluate the
sound and perform any additional adjustments as neces-
sary.
NOTE: It is almost always necessary to dial-in additional
sub-bass boost in order to overcome road noise which
increases with the vehicle’s speed. If using the Alpine |
4313 Remote Subwoofer Level Control, adjustmentin a —
stationary car is sufficient. The bass output can be in-
creased or reduced by the user. Furthermore, the original _
setting can also be restored by returning the conirol to ;
its center detente.
17. If the 4313 remote Subwoofer Level Control was not |
installed, it will be necessary to test-drive the car, listen,
and set the 3672’s Subwoofer level contro! to a compro-
mised value between the optimum setting for stationary
and freeway speed conditions.
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