Kenwood KAC-X811D Instruction Manual - Page 8
Band Reject Filter - problems
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Band Reject Filter 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. 0 dB Frequency 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 B.R.F. 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 B.R.F. FREQUENCY control to the position with which the peak observed on the spectrum analyzer disappears. 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 No sound. (Blown fuse.) POSSIBLE CAUSE • Input (or output) cables are disconnected. • Protection circuit may be activated. • Volume is too high. • The speaker cord is shorted. The output level is too small (or too large). The sound quality is bad. (The sound is distorted.) • The input sensitivity adjusting control is not set to the correct position. • The speakers wire are connected with wrong + /-polarity. • A speaker wire is pinched by a screw in the car body. • The switches may be set improperly. The sound does not change • The AMP CONT has been turned "OFF". even when you have changed it with the Amplifier Control. The set value cannot be • The AMP Control of the Center Unit is being used. changed by the Amplifier Control of the unit. The Amplifier Control cannot • An incorrect ID number is used for the Master amplifier. be operated from the Center • The ID number of the amplifier has been changed. Unit. SOLUTION • Connect the input (or output) cables. • Check connections by referring to "Protection function". • Replace the fuse and use lower volume. • After check the speaker cord and fixing the cause of the short, replace the fuse. • Adjust the control correctly referring to "Controls". • Connect them properly checking the + / - of the terminals and wires well. • Connect the speaker wire again so that it is not pinched by anything. • Set switches properly by referring to "Controls". • Turn the AMP CONT "ON". • Release the AMP Control mode of the Center Unit. • Always set the ID number of the Master amplifier to "0". • After you have changed the ID number of an amplifier, turn Off the POWER switch of the Center Unit first, then turn it On again. 8 English