Ok, here's my setup.

I have an Alpine CDA-9835 deck (60x4 watts, not sure if that's RMS), I just bouth some infinity 6012i (6.5" 60watts RMS) for my fronts, and Infinity 9612i (6x9 100w RMS) for my rear. I turn my deck past 20 (I think the max is 30 or 40) and I get distortion out of all speakers.

Any suggestions?

 

What do you have your bass and treble set at? also thos decks automaticaly have some sort of "bass enhancement" turned on ( I cant remember the name.. I just remember I have to turn it off every time I do anything to my car that requires that I disconnect the battery) make sure that is off ( some kind of "loudness" feature) all those things do is add distortion. and I would suggest keeping your bass and treble at 0 which is -- on an alpine. definately keep the bass at 0, you can ush up th etreble to 1 or 2 if needed.
I hope this helps a bit.

HD

 

One of two things.
1. They are out of phase which means you wired them backwards

2. They are not getting enough power. Add an amp.

 

If your getting distortion its because a headunit can only produce so much "clean" power. Once a deck is turned up so far that it can no longer produce sufficient power without overheating distortion starts. You can solve this by going with a good four channel amp that has adjustable crossover frequencies on the high pass filter and that will solve your problem. Phasing is not going to cause distortion, it will cause cancellation in harmonics and cause a flat tone with no real mid bass response. Get a good amp. You will be happy

 

Yeah, the lack of bass was because the phase was backwards on my back rear speaker. I think I will invest in a decent 4 channel amp.