SeatIbizaTDI

I´ve connected my MP3 player directly to the amp of my car, bypassing the head-unit. Everything is properly grounded directly to the same point, and I get no noise or hum. However, I get some loud crackles frequently, especially in bumps or when I hit some holes in the road. I also have them when something hits the computer. The computer is powered by an 140W "modified sine wave" inverter.
Is this a computer power supply related problem? Its strange, and I cannot get rid of it. Please help.

Thanks.

Ricardo

MP3Car.com

 

Fosgate

Mate it looks like a loss connection somewhere but its not in your inverter os PS.
its most likely the RCA (the plug output from your sound card) if this is loss or not well connected you will hear some crackling noises and stuff... so check that and generaly check all the connections in side your case... press the soundcard incase its not fully in its place and also check the ground to the case this also can give you this sort of problem if it has loss connection

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Fosgate

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Fosgate

System Comp V3 - In progress.
Low power MB with C7 CPU, DC-DC PSU, car ECU link, USB TV, GPS, 7" TFT, Wireless, Voice.

SeatIbizaTDI

First of all, thanks for your help.

It is not related to the signal. I hear crackles EVEN with the jack connected to something else. For instance, if I connect the jack to a discman, fine. When I turn on the computer, even if the signal is coming from the discman, I hear the crackles - the only connection between the computer and the audio system is the power supply!

Odd, isn´t it? This is a major head-twist...:-(

Ricardo

Fosgate

What sort of PS are you using?

__________________
Fosgate

System Comp V3 - In progress.
Low power MB with C7 CPU, DC-DC PSU, car ECU link, USB TV, GPS, 7" TFT, Wireless, Voice.

sproggy

Try to find out exactly what is causing the crackles.

If you hear crackles with the inveter running but not not connected to the computer then the problem is with the inverter.

If you only hear crackles with the computer plugged in then it a problem with the computer psu.

If the problem is with the inverter and it is securely grounded then try putting a capacitor (large value) across the input terminals of the inverter.

if it still crackles get the inverter replaced as it's probably faulty.

sproggy

Try to find out exactly what is causing the crackles.

If you hear crackles with the inveter running but not not connected to the computer then the problem is with the inverter.

If you only hear crackles with the computer plugged in then it a problem with the computer psu.

If the problem is with the inverter and it is securely grounded then try putting a capacitor (large value) across the input terminals of the inverter.

if it still crackles get the inverter replaced as it's probably faulty.

sproggy

Try to find out exactly what is causing the crackles.

If you hear crackles with the inveter running but not not connected to the computer then the problem is with the inverter.

If you only hear crackles with the computer plugged in then it a problem with the computer psu.

If the problem is with the inverter and it is securely grounded then try putting a capacitor (large value) across the input terminals of the inverter.

if it still crackles get the inverter replaced as it's probably faulty.

SeatIbizaTDI

It must be the computer power supply fault. It is a regular AT power supply, I don´t have any details.
I´ll try to connect other power supply, this is very old (it belonged to a 486DX/33).
I´ll send news when I get another PS and plug it.
Thanks again for your help.

Ricardo

MP3Car.com

 

minicooper

I have a similar problem - I think? I dont have the setup in the car yet BUT I am picking up hiss especially when the computer is turned on.... The hiss is there running off the invertor and running off 240v mains.

There is less hiss when the computer is turned off.

My power cable to the amp is 1.5metres (unshielded).. could this be the problem? It will be shorter when it is installed.

The soundcard (SB pci128) is connected to a sheilded 3.5mm>rca connectors. This is connected directly to my amp (Caliber CA 80wx4channels).


HELP please.. :O)

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Cheers

Duncan :O)

LoreleiGuy

It's obviously a power problem. Which means that it can come from two sources: the inverter, or the computer ps.

I myself had a crackly inverter (whistler 300W), simply exchanging it fixed my problem.

SeatIbizaTDI

I´ve changed my computer power supply, and the noise/crackles are gone. It was a power supply defect (a very old one)

Ricardo

sproggy

Crackles comming from the psu connected to an inverter would be caused by breakdown of the power factor correction capacitor inside the psu. Removing this should eliminate the crackle problem. Look here http://ashleypowers.homepage.com/power.htm for what to look for.

Hiss will come from a poor ground connection, ground loops or a poor quality sound card.

MP3Car.com