crackling/distortion-not engine whine

wifehatescar

I just hooked up my system and while car is off sounds fine, with the car on has the following problems:
During some songs more than others at some frequencies more than others there is a crackling/distortion sound from the front speakers only (mostly the tweets). Probably the sub too but can't tell as much there. It is not engine whine though, it sounds like the speakers are blown/screwed but whan the car is off like I said they are fine. What's up?

The system:
USAcustics 85x4 grounded well
2 channels go to momo component up front and 2 channels bridged to a 12"

The only thing I can think of is the power wire runs near the ECU but others have done this without issue. It's a 98 integra GSR.
Thanks

Jstas

Well, if you routed the power wire past the ECU, move it and see if that clears up your problem. However, I think you have either a bad ground or the gain on your amp is turned up too high.

wifehatescar

The gain is not even at 1/2 way on the 2 channels for the components.
How could the ground be bad? I connected it to the floor pan and grinded it down to bare metal.

How far from the ECU is sufficient? Inches? Feet?
And also, what kind of noise comes through the speakers usually if the ECU does cause issues? Is it more like engine whine or distortion?

Really, it may just be that most the songs I listen to are burned off the net. It seems like my system is VERY sensitive to recording imperfections, white noise (s/n ratio maybe?), etc.

Jstas

Well, I will address a few things here.

Number 1, gain isn't set by the numbers on the dial. Sure, they tell you what the gain is set at but you need to know what your output voltage is from your pre-amp outputs. If you have 4 volt pre-amp outs and set your gain as if you have 1.2 volt pre-amp outs, you'll get distortion because it's too much positive gain feed for the signal source. The higher the signal source's voltage, the less work the amp has to do to boost the signal and the less noise gets picked up by the amp's circuitry. If you have a certain pre-amp out voltage, set the gain on your amp for that. It won't do you any good to set it too much higher. Read the manual that came with your amp and read the manual for your head unit. Both will discuss pre-amp voltage and gain settings.

Number 2. A bad ground is not dictated solely by the point at which you grounded your amplifier. There are plenty of other grounds in the system including the radio antenna, especially if it is powere, the wiring harness for the car and even the chassis ground for teh head unit also, you car battery could have a bad ground or you system could have a ground loop in it. Any one of them could be bad, any one of them could introduce noise. That noise can be anything from severe radio intereference and static to the usually hiss, whine and click that comes from the ignition system and the physical emminations of the movement of the engine creating and EM feild. As for moving your power wire, there is no specified distance. It's not cut and dry. You gotta move it until you find a spot where the noise goes away. It's work and whether anyone likes or not, you have to do it. Not every car's ECU is the same either. So what works for a Chevy may not work for a Ford or a Nissan or a BMW. You just have to get your hands dirty and make it work.

Number 3. I have discovered your problem. Your recordings suck. If you are doing them yourself, you need to turn down the amplitude at which teh recordings are made. Your input signal is way too high and the D/A converter in your head unit is interepreting and trying to play the clipped recording. If you are getting them from another source online, find a new source because that guy/girl you are getting them from doesn't know what they are doing. Also, just because something sounds good on a computer sound card and cheap computer speakers doesn't mean that a high end stereo will make it sound better. The computer parts just aren't sensitive enough to bring out the real faults of the recordings.

Most computer sound cards and speakers are no better than a stock car stereo. Cheap speakers for mass production and not so great electronics that are operating in an extremely electricaally hostile environment. Sure, it may have 5.1 sound and a 20w x2 amplifier but so doe thes 20 dollarstereo from Kmart. Does it work? Yes. Does it work well? That's relative. Is it a reference piece of equipment? No, far from it. Your computer is an amazing tool. It give syou the ability to have the functionality of a professional editing sound board. However, unless you bought extremely expensive software, your average MP3 ripping software is no where near the quality of a professionally mastered recording.

I used to collect CD's. Then I got into MP3's like everyone else. I was converting MP3's to .WAV files to play in my CD player long before anyone ever heard of a .CDA file. Then I realized that no matter how free it was, some putz in Ohio or something with too much time on his hands could never give teh quality of recording that a music publishing house was capable of. I now collect CD's again and only bother with MP3's for travelling purposes. My advice is, if you really want good, cheap, quality recordings, join a club or something and buy the CD's you want. If you can't, then find a better MP3 source.