I had the grilles off the front door speakers to see what I could see - it looks like the speakers are in a sealed box, almost like mini-subs. They appear to be original (the head unit is an Alpine 7829). Is that what these are supposed to be?

The rear deck speakers seem to be original too. The dash speakers are either not in there or not connected.

I have a feeling that the after-market head unit is 4 ohms and the originals are 8 ohms, which might be why the sound is so pedestrian with what appear to be nice components. What can I do to improve the sound? Lose the 10-year-old Alpine, replace the speakers, hook up the dash instead of the doors?

I am going to check polarity to make sure it is not reversed, which is how it sounds. There is no amp in the trunk, I looked.

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1991 300 SEL
218,000 Km

"Xsbank's rules of mechanical intervention: Always go for the easiest solution first; 90% of what ails a gasoline engine is ignition; After that its all a WAG."