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

A lot of misinformation in here.

Yes, the oem speakers are abysmal and likely failing/being pushed past their limit when you have your volume turned up.

A fairly simple solution would be to replace the drivers. Though if you're doing that you may as well also amp them to get the most out of it.

Most component sets are 4ohm, so finding an amp to compliment them won't be tough.

for NVR I'd do cld tiles for 25% coverage on inner and outer door skin, plus door card

https://www.sounddeadenershowdown.com/products/cld-tiles

And just get speaker rings from modifry.

You don't need to use "slim" driver's anywhere, I was able to get some monster midbasses to fit without any trimming.
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Some clarification on that - the Polks will fit the stock speaker bracket. If you want something bigger, then the modifry speaker rings are the way to go.

This clipping at high volume was my original gut feeling about this. I was guessing that the problem is more likely due to over running the amp in the head unit then any issue with the speakers. This issue has been present from the get go. It is not new.

I am not generally dissatisfied with the sound - only at very high volume when I get this distorted sound. I could live with it by avoiding the very high volume, or I could spend money to try to fix it. Still uncertain which way to go.

I doubt very much that the speakers are physically broken - first, they sound fine at normal volumes, second, its a bilateral issue, not just one speaker. I don't think its eq settings, I have fairly normal eq settings and I did mess with that a bit to see if it was the cause.

You'd be surprised. I put Alpine woofers and tweeters into the doors. Model SPS-610C Plus, the 445A amp. CDE-SXM 145BT radio. And the speakers on the passenger side would distort at very loud volumes. I felt around the inner door access --> no problems. But, when I touched the passenger side rearview mirror --- the distortion stopped. It was NOT a buzzing noise. But, sounded just like clipping distortion. Odd.

Anyhow, padding the doors with sound deadening... stopped all "distortion."

:)

Some of the Alpine models have an inherent design flaw within their built-in amps, causing distortion at higher range volumes. I looked at people testing this theory with oscilloscopes on youtube and it really dissuaded me from getting an Alpine for this reason, and as well as not getting full voltage out of the preouts unless it's maxed out. I went with a Pioneer 80prs and full active with my build and so damn glad that I did

His sine wave shows classic crossover distortion. IIRC, this is not a function of the pre-amp. But, could be the phase inverter section, prior to the output stage. Or the DC offset of the output stage. Kinda find it hard to believe any modern-day, solid-state head unit (including OEM models) would show such a bad example of XO distortion. This is more common in the days of tube amplification and push-pull biasing of the output stage. Be nice to see his test gear setup. And how he calibrates it.

:)

I don't pretend to know the technicalities or the cause of it lol
Back when I was reading a lot on diyma I came across a good share of posts regarding it and was further swayed against that particular unit. It doesn't seem the TS has that particular one so it could just be a moot point.

I'd still suggest replacing the speakers, amping them, and enjoying decent sound quality. You can install it all within a day

If I use that small under dash amp that alpine sells and upgrade speakers, what are the good/best speaker options?

that Alpine powerpack amp does 90 Watts x 2 @ 4Ω Bridged, so pretty much any component set would work well for you.
Figure out your budget, musical preference, etc.. a lot of people here (and even this thread) suggest the Polk db line but I've never heard them

There's absolutely no overlap in the installation of the amp and the speakers, so you might want to install the amp, and if you're
happy with the sound you're done, and if not you can move on to speakers.
There are two versions of the KTP-445 -
KTP-445A which is plug&play with your Alpine headunit, but is wired for 45w x 4 channels so all you'll get is 45w x 2 channels that you have
KTP-445U which is universal, so you'd need to splice wires into your existing headunit harness, but can be bridged to produce 90w x 2 channels
In addition, Pioneer makes a similar amp, the GM-D1004

This is good advice. I'm going to start by sticking a KTP 445A in my car and see how it works out. Thanks for all the great advice folks. I'll report back when its done. It will probably be a month before I can get this done.

It nothing else, this will be a nice little experiment. If you change more than one thing at a time you can't tell what helped.

Has anyone installed one of these in a ap1? Where does it fit?

In my AP2 I ziptied it under the passenger side dash.

I had a KTP-445U installed today under the passenger side dash. The installer bridged it, so I guess I'm getting 90W to each door? Right? He ran the power supply to the battery. I have used this guy before, as have many of my friends, and all the work he has done for me has been excellent. He has installed systems in many S2k's over the years. It could be my imagination, but the system seems to perform quite a bit better, both at low volumes and at high volumes. It certainly has a lot more power.

So now I have an Alpine UTE 62BT head unit, and the bridged KTP-445U amp. I still have my stock ap1 (02) speakers and tweeters. I'll leave it this way for while and see if I feel the need for anything more.

One other question, with the amp power wired direct to the battery, will there be a battery drain issue at all?

Should be a trigger wire, which turns amp on when in ACC. Turns off, when you switch keys to OFF.

So I started this thread asking about the cause of distortion at high volumes. I installed this little amp. No more distortion. If I have a good quality digital file the sound is quite good with the oem speakers. No distortion. My conclusion is that the distortion was likely caused by over running the head unit amp causing clipping, not because of a problem with the speakers. Adding the new amp solved that problem.

I am still considering new speakers. Not sure yet. It is pretty darn good as is. I get enough clean volume at high speed with the top down to make it quite satisfying. But, maybe it could be even better?

If you're still on stock speakers, then new aftermarket ones will absolutely make a world of difference. Welcome to the slippery slope of car audio.

Toss the OEM CRAP! Ok that behind us. Best upgrade is new head unit to start.(powering OEM speakers) Then speakers alone to run off HU. Then it's speakers and amp together upgraded.

The reason for distortion 99.4% of the time is because the amp is being over driven and THD(total harmonic distortion) is reaching levels which can be hear. This happens with any amp regardless of quality. The people installing the amp(if done correctly) will set it up so you can turn the volume up 3/4 or so the way up before you get to that point. If they did it wrong you can turn it to 11 and it will still not distort or you can turn it no more than 3 and it's blowing your ear drums out.

I have worked in the industry so I know the good/bad and the god awful ugly/dangerous installs.

Oh and FYI it's VERY VERY hard to overpower a speaker with too much power. That being given that the watts delivered are clean and undistorted. What burns up voice coils is DISTORTION! This forces the voice coil to heat up and possibly strike the sides causing damage.