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The acoustic properties of vehicle compartment tend to
cause oscillation due to resonance or unclearness of
sound due to standing waves at certain frequencies.
The band reject filter can solve the problems of
resonance or unclear sound with minimum influence on
the sound quality because it eliminates only the
frequencies causing resonance or standing waves.
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Adjustment method:
The band reject filter cuts only the limited frequencies to minimize influence on the sound
quality. Therefore, its effect cannot be obtained unless the cutoff frequencies are set
accurately to the frequencies causing resonance and standing waves. The band reject filter can
be adjusted according to what you feel through your ears, but we recommend the use of a
signal generator or a spectrum analyzer with a fine frequency measurement capability for the
adjustment.
• Adjustment using a signal generator:
Output a sine wave, vary its frequency to find the frequencies at which the vehicle compartment
resonates or volume increases (standing waves occur), and set the BAND REJECT FREQUENCY
control to the position with which the resonance and standing waves disappear.
• Adjustment using a spectrum analyzer:
Output white noise (sound in which all frequencies are at a certain level), find the peak
frequency observed on the spectrum analyzer, and set the BAND REJECT FREQUENCY control
to the position with which the peak observed on the spectrum analyzer disappears.
Frequency
0 dB
Troubleshooting Guide
What might appear to be a malfunction in your unit may just be the result of slight
misoperation or miswiring. Before calling service, first check the following table for possible
problems.
PROBLEM POSSIBLE CAUSE SOLUTION
No sound.
(No sound from one side.)
The output level is too
small (or too large).
The sound quality is bad.
(The sound is distorted.)
• Input (or output) cables are
disconnected.
• Protection circuit may be
activated.
• The fuse may be blown because
the volume was too high.
The input sensitivity adjusting
control is not set to the correct
position.
• The speakers cable are
connected with wrong + / -
polarity.
• A speaker cable is pinched by a
screw in the car body.
• The switches may be set
improperly.
• Connect the input (or output)
cables.
• Check connections by referring
to "Controls".
• Replace the fuse with a new
fuse and use a lower volume.
Adjust the control correctly
referring to “Controls”.
• Connect them properly checking
the + / - of the terminals and
cables well.
• Connect the speaker cable again
so that it is not pinched by
anything.
• Set switches properly by
referring to "Controls".