Alpine 3672 - System Adjustments; General Requirements for Adjustment; RTA-Based Adjustment Procedure

3672 |
Adjustments
GENERAL REQUIREMENTS:
The Alpine 3672 is a very precise and versatile piece of
equipment. It should be adjusted by an autosound specialist
who possesses the knowledge and the tools to accomplish
this task accurately. It would be helpful to use a Real Time
Analyzer (such as Alpine 4780), but it is not absolutely nec-
essary.
* Itis imperative to have easy access to the 3672 while it is
being adjusted. If it is to be mounted permanently in a
location which will not allow easy access, it willbe neces-
sary to temporarily relocated the unit by using long audio
and power extension wires.
* Before any adjustments can be made, all stereo system
components (except for the 3672) must be permanently
mounted in their locations, and the passenger compart-
ment should be completely reassembled, as removed
door panels or seats will affect the frequency response of
the vehicle's interior.
* The vehicle’s doors should be closed and windows rolled
up. This may require temporary relocation of the 3672
outside the vehicle’s passenger compartment (if it is to be
permanently mounted there) using long extension wires.
* The trunk can be left open if the passenger compartment,
including all the speakers and speaker enclosures, are
sealed off from the trunk.
* Check the component speakers’ specifications for their
rated frequency response. The active crossover frequen-
cies used for each speaker must fall within its frequency
response. For example, a mid-bass woofer rated from
60Hz to 300Hz must not be driven with frequencies lower
than 60Hz or higher than 300Hz. Otherwise, the sound
quality will be severely degraded and speaker damage
may also result. Therefore, tentatively adjust the 3672
crossover points. not to exceed the frequency response of
the drivers and remember to stay with in these boundaries
during the adjustment procedure.
RTA REQUIREMENTS AND SET-UP
* It will be most convenient to have the 3672 as close as
possible to the RTA during adjustments as it is easier to
monitor the changes made by each control.
* This RTA should cover at least 20Hz to 20kHz in at least
one-octave increments. It should also possess the ability
to analyze and display frequency response at 100dB or
more Sound Pressure Level (SPL).
* As there are many different makes and models of Real
Time Analyzers, it would be impractical to define set-up
procedures for a specific unit. Therefore, you will need to
familiarize. yourself.with the particular model of RTA you
will be using to adjust the 3672. The RTA’s owner’s
manual can provide all the necessary information.
Alpine’s 4780 Third Octave Analyzer can provide excellent
accuracy, versatility and ease of operation.
«x Ahigh quality, calibrated microphone. should be used with
the RTA. The RTA manufacturer can recommend a suit-
able model. This microphone should have a very flat
response throughout the audio bandwidth (20Hz to
20kHz). The Alpine 4780 RTA includes a calibrated mi-
crophone.
NOTE: RTA adjustments must be done in quiet surround-
ings. Noise from wind, traffic, or other car stereo systems
will affect the RTA readings and throw off the adjust-
ments.
After all the general requirements are met, proceed as follows:
1. Position the microphone on a microphone stand placed
on the driver’s seat, in the same position and height as the
tight ear of the driver.
2. Connect the microphone to the RTA. Set the controls for
non-weighing and greater than 100dB range.
ADJUSTMENT USING AN RTA:
1...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
4313 Remote Subwoofer Level Control (if ued) are in the
center detente (neutral) position. Also verify that the Input
Mode Switch, Subwoofer Fading Mode Switch, Subwoo-
fer Stereo/Mono Switch, and Front and Rear Crossover
Mode Switches are set as needed.
2. Using a test CD or tape such as the Alpine Official Refer-
ence Software, select the "Pink Noise" track and set the
volume control of the system for anominal 100dB average
sound pressure level.
Perform the following steps with all doors closed, win-
dows rolled up, and the vehicle interior completely intact:
3. This sound level will give you a display on the RTA screen.
This display is the frequency response of the total system
(the sound system and the vehicle's interior together). It
may look somewhat similar to the one shown below: