Suggestions on Basic Car Stereo Setup

You've pointed out the one benefit to a 6x9:  it can play _slightly_ deeper than a 6.5" round. 

Car makers put oval drivers in cars to fit a speaker in.  The oval shape is not optimal.  Physics people, please help me out here, but I've been told that the oval shape can distort easier because of the uneven stresses on the cone and the surround.  Additionally, I've always thought that the tonal quality of 6x9" speakers is poor.  Does someone have a physics related reason for this?  The crossovers on a $200 pair of 6x9's are generally crap compared to a similarly priced 6.5" coax or component set. 

Do you ever see oval speakers on expensive home audio systems?  No.  It simply isn't the optimal design. 

I think my biggest complaint about 6x9's is that the rear deck is a poor place for midrange / highs unless you're doing some sort of multimedia thing or don't care about having the best possible sound for your budget.

Quality car audio sound will create a nicely imaged front sound stage.  6x9's muck this up.  Furthermore, because each 6x9's will be further away from your ear than the other drivers in the car, the sounds from the 6x9's will be reaching your ear at slightly different times than the front speakers.  This is bad. 

Finally, even if you don't get some harsh reflection off the back glass (every tweeter I've ever heard firing into the rear glass sure sounds harsh to me), your 6x9" driver isn't exactly 'on axis' or pointing at your ear.  This means that certain frequencies the 6x9" driver produces will sound more pronounced than others from your seat.  One of the goals of quality sound is smooth frequency response.  I find that 6x9's in the rear deck generally work against this goal. 

Again.  I'm not saying you can't have a good sounding car with 6x9's!  All I'm saying is that they are less than optimal for sound quality and I think your money is better spent working on some sub bass and a quality front stage first. 

Not all cars have the rears pointing at the glass, kfr01.  So we have to take each situation into account.  I use speakers in the rear deck in my car for three reasons:  mainly, when adjusted just right they "pull" the front soundstage out of my lower doors and up into the air around my head.  They could only muck up the sound if you were able to hear them.  Attenuated properly, you don't (sitting in the front).  Secondly, they provide stereo sound for my daughter and her friends when we're out driving somewhere.  And third, they are there because the car had factory originals there. 

The back deck is angled toward the front, and there is no harshness coming out of those rears.  In fact, sitting in the rear seat, one gets the same effect as sitting in the front:  the sound is pulled by the other set of speakers so that it isn't so easily located.  So, the car itself is a determining factor.  Another factor is the quality and placement of the fronts.  If door locations are used, the rears can be helpful.  But if the fronts by themselves are perfect and no help is needed for imaging, leave out the rears.

I certainly agree that the rears should be a lower cost consideration in relation to the fronts and the sub.  In most cases, coaxials are totally appropriate here even when very fine components are used up front.  And they can certainly make for some good bass while the subwoofer aspect is bought and paid for and worked into the system.  I would buy them as closeouts on the internet, and have no more than about 50 dollars in them for the pair.

I was not aware that some decks don't point straight at the rear glass;  I stand corrected on that point. 

Stevdart, I agree with everything you said.  Your post was very informative.  I actually think you highlighted my point well:  Rear speakers should take a lower priority in the budget than the fronts and sub.  For the best sound they should be carefully integrated into the system and attenuated, not cranked to the max.

vbel:  Quality subs don't "boom boom."  In many cases a quality sub in a sealed box will be tighter than a 6x9 infinite baffle setup.  I don't listen to any rap.  The difference and quality a subwoofer can add is huge for any type of music.  I primarily listen to contemporary vocals, jazz, and rock.  6x9's are not subwoofer replacements.

Yes, defective, it was about Basic Car Stereo Setup.  I stand by my original statement for a Basic Car Stereo Setup:  6x9 rears should have a lower priority in a small budget than front stage and sub bass.  How is that not basic advice? 

A lot of you have said, 'it just has to be good enough for the owner' or 'my setup is just fine.'  I couldn't agree with you more.  Sometimes a completely factory system is 'good enough.'  But, when someone asks for advice on a budget and requests SQ, I'm not going to say, 'oh, just buy 6x9's.' 

Advice is about the advisor sharing what would be OPTIMAL for the advisee given a request and budget restrictions.  I'm sorry, but you simply aren't going to convince me that having a 6x9 set turned up so it is a 'subwoofer replacement' is anywhere near optimal.  A patch until you get a subwoofer?  Fine, but I wouldn't recommend spending much money on it. 

Again.  Is 6x9 sound 'good enough?'  Not for me.  It might be for you.