Crackling in audio while driving - not sure how to troubleshoot

**Moondog51** · 08-26-2005, 09:37 AM

Im getting frequent crackling/popping sounds when I play music from my carpc.
-The problem doesnt seem to start occuring until Ive been driving for 10-15 minutes.
-Ive never noticed it happening when Im running the carpc with the engine off, but I also havent sat with the music playing for 10-15 minutes with the engine off either.
-It doesnt seem to be connection related as the crackling occurs even when the car is standing still.
-The problem seems most evident in music with a lot of high notes, like classical music for example, and seems to pop/crackle right after a higher note very often.

Im not sure where to start troubleshooting this. I initially thought it could have been an inadequate ground, and so I redid my grounding point on the car chassis and im pretty confident its good now.

Anyone have any ideas on what could cause this, or ideas on how to isolate what component is causing the problem?

**wizawuza** · 08-26-2005, 09:43 AM

I know you said you don't think it's a connection issue, but for me, whenever I have symptoms like that, it's a connection issue. I'd suggest perhaps trying the music with the engine off for 15 minutes. If battery dying issue are a concern, perhaps you can find an old battery somewhere? I dunno.

Also, is the problem the same if the volume is high vs if the volume is really low? (but high enough that you can still kinda hear the crackling if you really try)

In my old setup, one of the RCA's was slightly loose, and only when accelerating hard, or having the bass hit half decently hard, the thing came loose.

Good luck

**Spyder1331** · 08-26-2005, 04:49 PM

Could bother you for some backround info for all of us looking at this: mods/additions-driving lights, etc., the equipment you are running, audio-amp(s)? a cap? 90% of signal related issues are traced back to a poor or loose connection.

**Moondog51** · 08-26-2005, 06:13 PM

Ok, so heres the latest. I loaded up a playlist of classical and proceded to listen to it pop and crackle all the way home. When I got home, it was still happening with the car stopped and idling.
First thing I did was copy the mp3 that was currently playing onto my psp. I unplugged the sound card from the amp completely, plugged the psp into input 1/2 on the amp and played the mp3. It sounded perfectly fine on the speakers in the car.
So, I ran into the house and got some headphones, plugged them into the soundcard (I had left the music playing), and lo, the damn thing was still popping and crackling.
So, its at the sound card or in software.
So, what are the possibilities here?
Bad ground (still)
Bad sound card
Bad mp3 codec?

Heres the relevant parts of the system specs-
*OPUS 150 watt DC-DC power Supply
*MSI K7N2GM-V Socket A (Socket 462) NVIDIA nForce2 IGP Micro ATX AMD Motherboard
*AMD Mobile Athlon XP-M 2200+
*Audiotrak Prodigy Sound card

**maxxell** · 08-26-2005, 09:47 PM

It might be something as simple as finding a setting on your soundcard. I know when I first installed my Soundblaster Audigy PCI soundcard I had something similar and eventually found something that solved the problem. Sorry to say I couldn't tell you what the setting was, though.

**Spyder1331** · 08-27-2005, 12:17 AM

Yes it could still be a bad ground although you are more likely to hear your RPM's or a noise that sounds like it more than crakles. It very well could be that excess power is backfeeding. When this problem occurs with a TV you will see sparkles in the picture. So I suggest you put a voly/ohm meter on the power lines. Let me know via PM what your results are.

**Stacker** · 08-27-2005, 04:37 AM

I agree if he hears it in synch with a fan or alternator or A/C, but not when engine is off, I say 99% ground issue 1% due to fuel prices.

**numbers** · 08-27-2005, 08:29 AM

Aside from loose connections, cracking/popping noises are also frequently associated with overheating components. The fact that it only starts after playing for a while may support this. Additionally, when dealing with computers, software opens up an entirely new universe of potential problems. Popping can often be the result of very short buffer underruns caused by some other program hogging resources. It would be best to try to narrow it down to hardware or software somehow before going any further so you don't wind up wasting your time.

**Moondog51** · 08-27-2005, 10:48 AM

Originally Posted by Spyder1331

Yes it could still be a bad ground although you are more likely to hear your RPM's or a noise that sounds like it more than crakles. It very well could be that excess power is backfeeding. When this problem occurs with a TV you will see sparkles in the picture. So I suggest you put a voly/ohm meter on the power lines. Let me know via PM what your results are.

What will it look like on a multimeter? I have a fluke multimeter, but I am not very adept at its operation and interpretation. I also have access to an osciliscope if that would give a better indication of a problem.

To throw another wrench into the works, while doing searches on this issue on google I stumbled acrossed conversations on audiotrak's user support forum that indicate this problem happening with other people. Non car-pc people, with regular machines. No one on has been able to resolve it yet, and theres a disheartening lack of acknowledgement and support from audiotrak. So, it may just be a bad card and I am sol. Im going to try a couple arcane bios changes suggested on their troubleshooting page and see if they make any difference, even though they dont apply specifically to my mobo.

http://www.esiforum.com/show.asp?db=...mode=0&msg=548

Im seriously thinking of just tossing this card and getting a creative X-Fi extrememusic card when they become available.

**Spyder1331** · 08-27-2005, 12:50 PM

Fluke meters are great, awesome choice! They are my choice as well, do you find it funny as well that it is a "fluke", but dead on accurate, oh well. Look for higher than normal voltage, the average for a car is 10.7v to 14.1v. If it is higher then odds are you are getting more power to your PC powersupply, and it is being distributed throughout your components. To test this, simply put your leads on the positive and negative wires of your power supply(not connected to your PC), and note the value. Do this for the input of the power supply and the output as well. Now only put the positive lead to the power supply and the negative to a bare spot on the chasis of the car. Do the values match? If the first test is higher there is a bad ground within the power unit, if the second is higher than you have a bad ground before the power supply. Now using that same meter you can get a 75ohmtransistor and test your wires if you want. DISCONNECT POWER! To do this put the resister at one end of the wires so that the resister bridges the positive and negative at one end and at the other match positive/positve and negitive/negitive. By doing this you are completing a circuit and you shoud read 75ohms if the wire is good, if less try another transistor to be on the safe side.