Question about Kenwood KAC-8403 Car Audio Amplifier

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Beeping sound from amp when car headlights turned on


I have fitted a Kenwood KAC-8403 amp and a KSC-SW1 sub-woofer into my 2006 Subaru Outback 2.5i (with the standard Subaru head-unit). I have absolutely no complaints with either of these components, the sound is fantastic.

However, I do have a problem that I hope you can help me with.

When the amp is powered on (head-unit can be on or off - doesn't matter) and I then turn on the car's headlights, I hear a single (high frequency) beep. This beep then recurs once every 30 seconds to 1 minute, while ever the headlights are on - detracts from enjoying the music somewhat.

When I turn the lights off - no more beeps. I've checked and the sound is coming from my speakers. The amp is connected directly to the car battery (fused) and earthed directly back to it with 4# multicore wire.

Any ideas of the cause and the fix? Hope you can help.


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Re: Beeping sound from amp when car headlights turned on

It could be a indication of low amps.

Does it happen when car is running and lights are on?

If car is off do lights dim to the music at night?

You could be using more power than your alternator can supply.

Most alternators are capable of producing 55-65 amps. This is adequate for sound systems producing up to 350 watts RMS. Some more modern vehicles have alternators rated up to about 120 amps. This will be sufficient for systems of up to about 600 watts. Some pre-1985 cars, on the other hand, have alternators only rated for 35 amps. This will only support about 125 watts in amplifier power.

One easy, effective solution maybe installing a capacitor. Heavy-duty capacitors connect to the power cable (just before it reaches your amplifier) and act as a buffer zone between your amp and your car's electrical system. They store up a reservoir of power which can supply the amplifier's peak demands (like a bass drum beat) without having to draw current from the battery.

First, Check your earth is excellent and not all clustered on one point. Ensure power leads are thick and secure. Separate speaker and power cables.

Check auto turn on wire (thin blue on amp) is not connected to lights power source, use elect aerial output on head instead

Run 4 gauge earth wire to car body near amp, power cable must be heavy gauge too, expessally with a sub woofer running.

Posted on Jan 31, 2008

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Re: Beeping sound from amp when car headlights turned on

Get your ground from the rear .i thing the ground you are noew using is in the path of you rear lights therefore you will get interference,also you can put a groundloop between radio and amp.that connects to the rca cables.

Posted on Jan 31, 2008

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