Basically I brought an 02 plate black clio for my first car. The audio system inside was standard apart from the head uni which was a pink (yes pink...) ministry of sound peice of junk. I drove from the garage I brought it from to my house with a distortion from the speakers whenever i turned my music up slightly. Due to the stereo being pink I decided to go buy myself a Kenwood stereo from halfords which had aux so I could connect my Ipod.
I brought http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogI d_10151_productId_757025_langId_-1_categoryId_165474 which I thought would be decent. I fitted it as soon as I got home but no joy. The speakers were still distorted and crackled at a medium volume.
I called a local store which is known for being one of the best audio centres around the west midlands called basejunkies. I told them of the problem and they suggested I buy new tweeters and front door speakers. I basically had nothing to lose from buying new speakers so I brought a set of http://www.bassjunkies.com/audio/mb-quart-dkf-113 which come with the tweeters.
Im not to good with audio so I fitted the speakers in the door without using the crossover as I wouldn't of been able to fit it. (a friend said there wouldn't be a huge difference in sound quality without it). I also swapped the standard tweeter over with the new ones and again tested the stereo. STILL DISTORTED.
I took it to basejunkies and they tried swapped the stereo over to a pioneer one and then a sony one, all the time there was a distortion. The tech guy there said one thing I could do was take out all the speakers one by one and test if there is still a distortion, this was to test if one speaker was basically cross wiring the others. I did this at home and no joy, every speaker sounds the same DISTORED and CRACKLING.
I phoned around now to see what the problem is and I've had so many answers with so many different prices etc.
Ive been told to get an AMP, new speakers and a full rewire. I can understand the rewire as thats the only thing not changed from before but an AMP? why do i need an AMP for?
The setup of the speakers is just standard, 2 front 2 back 2 tweeters. The volume of the distortion isnt loud at all, I can drive at around 40-50 mph and no be able to hear my music so not loud AT ALL. I have turned all the bass and treble down to see if it was that but nothing.
The amp is a selling gimmick (though admittedly it will sound better than the tiny amp in your head unit), but ultimately you really don't need it to avoid the distortion.
It sounds like it's a grounding problem with the head unit. I bet you could hook up a speaker directly to the head unit harness and the speaker would still distort.
Check your black ground wire. If anything, you might try grounding it somewhere else (it's likely just grounded through the factory harness). Just make sure the metal is clean i.e. rust free, and the connection is solid. You might even experiment with some different points to get the best ground.
I would take out the head unit get a few peices of wire connect to the battery, power the hu and connect an independent speaker, all outside of the car and test...