Noise on audio from laptop

**pip** · 04-07-2004, 02:21 PM

I hope some of you people with more experience than me can help with this one:

My plan is to connect my old laptop (Gateway Solo 9300) to my Corvette audio system to use it as a carputer. I have a dongle that connects to the CD-Changer cable in the corvette to provide an aux-in. This works really well and the sound is really clean, I've been using it with my Archos MP3 player for some time.

I installed GPS s/w and Audio Engine and connected the headphone socket of the gateway to the aux-in and it played really clean audio. However, I connected the car/plane 12v to 19v power adapter (bought from gateway at the same time as the pc) and I immediately started getting noise in the audio. This noise is not a ground loop but is noise generated by hard disk accesses and mouse movements on the PC.

Is this the power adapter? Would getting another one make any difference?

Would a USB sound card fix the noise? Should I say 'stuff it' and build a dedicated carputer and forget the laptop? Though, apart from the noise the laptop is working just fine.

Help?

**pip** · 04-08-2004, 11:43 AM

Any ideas?

**wizardPC** · 04-08-2004, 01:16 PM

Originally Posted by pip

This noise is not a ground loop but is noise generated by hard disk accesses and mouse movements on the PC.

I always thought that was a ground loop. Your laptop power adapter is causing the problem--it needs to be grounded properly. I understand that you probably dont want to cut it up, but you gotta do something to ground it better. The ground for the Cigarette lighter is horrid.

**Jonjonr6** · 04-08-2004, 01:25 PM

When I tried a laptop configuration before, I found that the only way to clean those noises out was to ground the laptop battery to the car chassis. Not desirable unless you don't mind making mods to your laptop. You can try using chassis ground for you audio input signal ground to the amplifier. Most people might say NO! don't do that, but they don't realize that 99.9% of the car stereos and amplifiers out there use basically chasis ground as the gorund for the audio signal, hence ground loops and engine noise. You have to spend alot of money to get a true balanced line output from a high end headunit.

**pip** · 04-08-2004, 01:30 PM

Thank you both, I'll try to improve the ground & see what happens.

I still may go the route if a mini-itx pc, especially now I see that PentiumM ITX boards are being made