What is likely cause of distortion.
 

I have an Alpine HU - BT only. I like it. Other than that, I have a very low mileage 02 ap1 with stock speakers that seem to be in very good condition. . Believe it or not, I think it sounds very good, most of the time. Recently, however, I noticed that when it is really cranked up on the volume with certain tunes I am getting distortion. I honestly rarely crank it up like that - my music tastes are not bass heavy and I just don't have a problem normally.

But, is the distortion I am hearing at very high volume something likely related to the speakers - or the lack of an amp - both? I'm considering an upgrade, but I'm not sure what to do first. One option, the one I am leaning toward now, is to do nothing. But, I seem to think about it pretty regularly, so on some level I guess I am slightly dissatisfied.

Speaker polarity matches the amp on both. There's a + and - notation (or should be) on the speakers and the radio.

Your speakers are likely being over powered by the amp but if not there are noise suppressors for sale inexpensively, even at Walmart for $10.

https://i5.walmartimages.com/asr/48b...0&odnBg=FFFFFF

-- Chuck

The extra wattage of your Alpine (versus OEM radio) maybe overdriving the speakers. And/or causing parts or the door to rattle. This includes the rear view mirrors, on the doors.

A layer of sound deadening insulation make help.

Replace the stock speakers ASAP, they are junk. I got the polk kit and it was a substantial upgrade over stock, not sure if they work for AP1, does yours have a separate tweeter in the door?

I did this before updating the head unit and stopped there because it was that big of an upgrade and let's face it this car will never be the pinnacle of audio.

Yes mine has separate tweeter in door.
I agree re the inherent limitations of the S and sound systems.Which is why option #1 right now is "do nothing. "
I don't think it is the door components rattling - its the speakers distorting.

From what you all are saying - it seems that a new set of door speakers might be the next logical step. And maybe while I am in there I could do some sound proofing as well. So - that brings us to the $64,000 question, what speakers? And, should I do it myself?

I'd get the polk again in a heart beat model Db6501, it took a little fabricating of plastic rings, gluing, and soldering but ended up with a great fit. It was not a hard job but also not a matter of a un-screwing and doing a straight swap.

They come with a big crossover, no comparison to the rinky dink stock setup. As an added benefit they are marine rated for the times you leave your window open at the track and it rains :banghead:

Forgot to mention in my previous post the reason I looked at doing a speaker swap was my stock speakers also had a "distorted" sound and isolated it to the passenger side woofer being blown.

I second what people have said here. The stock speakers sound like crap when they have to play at volumes audible above road noise. I also went with Polk DB6501s but I think the current model is the 6502, but I have an Alpine KTP-445U compact amp powering them. I used a set of pre-made speaker spacers so I didn't have to do much custom work to get everything in.

I have a somewhat different take on this...
Generally, distortion at high volumes is caused by an amplifier "clipping" - an amplifier is driven past its ability to fully reproduce
a high-amplitude sound wave, so the top of the wave gets chopped off making a square wave.
That said, it sounds like this is a recent phenomenon. If it's the same music played at the same volume but now distorted, it could
be a mechanical failure of a speaker.
Another possibility is a change in headunit EQ settings - because low frequencies require much more power than high frequencies,
changing a bass-boosting setting could cause clipping.
On the other hand, if you're simply cranking the volume more, especially if you're going above 3/4 of the maximum, I think you need
more power. In this case. since you're not generally dissatisfied with your sound, I'd go with an easy to install mini-amp like the previously
mentioned Alpine KTP-445.
Whether you add an amp, change your speakers, or both, if you're even slightly handy I'd recommend DIY. Neither is particularly
challenging, and you're more likely to do it right than an underpaid, rushing, installer.

Upgraded our crackling factory speakers with factory HU to Polk Audio DB651s. (S = slim fit)
Direct fit, no trimming needed.

I don't pretend to understand all this but do know that the amp and speakers need to be matched as to the impedance (in Ohms) of the speaker and output. Amps often have a range of acceptable speaker impedances.

-- Chuck