I think it's because the speaker adapters in the doors are just adapters - the drivers themselves aren't mounted to a sealed enclosure of any sort. The inside of the doors aren't sealed (obviously) and the mid-bass and midrange sound hollow - because it is!
For [MENTION=84801]AKmoney[/MENTION] and the OP, I used a sound deadener in my doors, and it made a huge difference in sound quality. Dynamat is the big name brand, but you pay a premium for the name.
I went with an "off brand" solution that is still butyl rubber with a thick sheet of aluminum on top. The off-brand saved money.
One order was about the same thickness as dynamat, the other was thinner but I was still pleased. "Stinger" is the name of one of the off brands. I can't remember if this was the same or thinner than dynamat.
The thing about sound deadener in general, is that you get the best performance by covering 60% to 70% of the metal surface. People who cover everything in dynamatt, and then even add a second layer, a going for overkill, and I'm not sure if they are seeing an improved or even equivalent outcome... not to mention the substantial weight they are adding to the vehicle.
The whole idea of the sound deadener, is to provide damping to PORTIONS of the metal, to reduce vibrations, and to try to disrupt vibrations at the frequencies where the metal will naturally tend to resonate. I believe you do this best by having some irregular shapes put in at different spots inside the door. By putting in some irregularly sized pieces, it can make a big difference. The reason why you don't want to cover 100% of the metal is that if you cover everything, you are mostly just changing the frequencies at which your effective "speaker enclosure" will resonate, while covering large portions in slightly irregularly shaped pieces, you are only changing the resonating frequencies of those parts that you covered. The idea is parts covered and other parts not covered will have a combined effect of doing a better job of dampening all vibrations over all frequencies..... almost the way a honeycomb structure can be stronger than a solid piece of material.
If you use sound deadener, buy a "roller" tool to apply it. It does a good job of adhering the material tightly to the contours of your vehicle's metal, and it works so much better than trying to press by hand, or using the handle from a screw driver (I've tried all three approaches).
I'm also not too impressed by the Infinity tweeters. They sound overly bright in the 6K-10K range but they roll off sharply above that - like nothing above 15K. I think it's because they don't have good off-axis performance and the stock tweeter location in the front doors don't angle them towards driver and passenger enough. Alas, I can't be bothered to upgrade/tweak things any further... I guess I'm just lazy.
I agree that the infinity tweeters sound overly bright, and at times they can seem harsh -- and I'm a big Infinity fan!
In the past, I had an older set of pioneer components, and I found them to be better than stock, but not as musically rich as I would like. I was a bit disappointed. Pioneer radios are awesome. Pioneer speakers are, IMHO, just so-so.
In my current set up (less than ideal but pretty good), I have infinity 6x9 coaxials in the door. The tweeters were too harsh (I think they were made of metal). So I bought these alpine 1" silk dome tweeters for about $50 a pair,
and using the supplied crossover, mounted them in the factory location of the high-mounted door speakers. Then I simply cut the wire in the coaxials that leads to the tweeter part of those speakers.
WHAT A DIFFERENCE.
The alpine silk dome tweeters sound great without being harsh or overly bright. I think the silk really helps in keeping the timbre smooth, and the dome shape helps with sound dispersal.
I'll probably go to a 6.5" round speaker in the lower door position at some point, and I expect to see an increase in sound detail when I do.
i ended up buying component speakers from pioneer ( 6.5 front 5 1/4 rear) per crutchfield (bought from amazon).... i will be installing the deck on saturday... can someone explain the parking brake wire and where i connect it to?... i have installed a few non nav/dvd stereos but this is my first dvd stereo install... the pioneer harness has a long green wire labeled "parking brake" i see tons of post for bypassing it, i dont care for any of that as i will not have video playing when driving...
Any more info on the parking brake wire? Anyone?
Search the12volt.com You can find the necessary wiring information which includes the location of the wire for your vehicle and the color coding of the wire that you need.
Enjoy!