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Car Audio Do you live in your car? Then you need to be able to listen to some high-quality music.
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Old 03-09-2004, 10:42 AM   #1
kennylbw
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"BOOM" sound after the head unit is off.

Hello,

I need your advice here. I have just brought a ENZER amp and it is connected to my front speakers.

Everytime, I switched off the head unit, i get a "boom" sound.

How can I resolve this problem?
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Old 03-09-2004, 02:43 PM   #2
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Re: "BOOM" sound after the head unit is off.

From what I've found that's normally caused by a bad ground. Did you sand off the area where you bolted the amp's ground wire to?
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Old 03-10-2004, 10:30 AM   #3
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Re: "BOOM" sound after the head unit is off.

Try turning the gain down too
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Old 03-10-2004, 11:58 AM   #4
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I have also installed grounding cables in the car.

Even when I disconnect the signal cables (audio input) from the amp composite input, this 'boom' sound is produced when the head unit is switched off.

I try to adjust the gain to see if there is any improvement.

Update your guys again.
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Old 03-10-2004, 12:29 PM   #5
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Re: "BOOM" sound after the head unit is off.

grounding cables?
you mean in the engine bay?

I'm talking about the actual amp ground, how well is it bolted down? How clean is the grounding spot?
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Old 03-11-2004, 08:58 PM   #6
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turn off thump is because that amp has a bad or non existent muting circuit and doesn't block the power shut-off fast enough and the thump is heard. often this happens in cheaper board designs

solution can be found at turn-off thump
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Old 03-11-2004, 10:13 PM   #7
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yep, it's a problem with the amp. This used to be a common problem
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Old 03-17-2004, 10:13 AM   #8
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Thanks very much for the help. I have read the suggested article but don't quite understand how the connections are made.

The article says, "This kind of problem is often caused by transients in the signal processor as it powers down finding their way into the signal path, which the amplifier then transmits to the speakers.

Usually this can be solved by adding a little turn-off delay to the processor. This allows the processor to stay powered on for a short time after the amplifiers have powered down, thus preventing the pop.

Many components sold today (such as crossovers, equalizers, etc) have delays built-in. Read your manual to see if it is possible to set this delay on your piece of equipment or be sure to look for this feature during your next car audio purchase.

If your processor does not have this feature, you can build your own delay circuit with a diode and a capacitor. Add a 1N4004 diode in series with the processor's turn-on lead, striped side towards the EQ. Then add a capacitor in parallel, the (+) side of the cap connects to the striped (processor) side of the diode, the (-) side of the cap goes to ground (not the radio or EQ chassis - connect to the car chassis).

Experimenting with the cap value will give you the right amount of delay before the EQ shuts off. You don't want it too long, just long enough to make sure the amp is off before the EQ powers down. 220 - 1000 uF is about right, and make sure the cap is a polarized electrolytic, 16V or higher. Also keep in mind that the diode will introduce a 0.7V drop on the remote wire, which can cause the processor to power down before the rest of the system. "

I am keen to give it a try but i would make sure i do it correctly.

What exactly does the processor mean here? the amp or head unit or something else.

Is the circuit connections correct based on the desciption above.

Cable: Remote On Remote On Coaxial
Head unit-----AMP-------|>|------------ EQ --------- Speakers
+pos Diode -neg | +pos
Capacitor
| -neg
|
Gnd
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Old 03-17-2004, 10:46 AM   #9
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The connections are distorted after i replied the posting. I will try to explain in words then.

Please correct me if i am wrong.

As my audio system is done by a third party installer, i suppose the connections is this way.

The Head Unit audio signal output is connected to the EQ. The EQ audio signal output is then connected to the AMP and lastly, the AMP to the speakers. The Head Unit remote-on is connected in parallel to the EQ and the AMP.

Is the above connections correct?

So the article suggests that a diode is connected in series (Remote on cable) from the Head unit to the EQ where the Anode (+pos) end is connected to the Head Unit and the Cathode (-neg) end is connected to the EQ. And the capacitor +pos end is connected to the Diode Cathode and the capacitor -neg end is connected to the ground.

Is my understanding correct?
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Old 03-18-2004, 10:41 PM   #10
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Re: "BOOM" sound after the head unit is off.

the diode and cap are in line with the remote turn on
remote----diode---+ cap-------amp
negative side of cap-----ground
you can get these parts at radio crack
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