Front speakers on a 5.1 system have low tinny sound

It sounds like the woofer part of the speaker is bad, while the tweeter is still good. You are going to have to replace the speaker. Speakers are generally sold in pairs, so it would be best to replace both rear speakers at the same time.

THE DOOR SPEAKERS ARE MADE TO SOUND LOW FREQUENCY THROUGH THE AMP,(60HZ-500HZ). THIS IS NORMAL. THE REST OF THE SOUND WAVES (500HZ -8000HZ) COME FROM YOUR 2 TOP SPEAKERS ON DASH NEAR WINDSHIELD, 2" TWEETERS.

Hey ajn1n1 we need to fine where the tinnyness is coming from Lets do a test shall we,

hook up your voice matched polks to your front left and right speaker outputs on your amp to see how they sound as mains. if you hear tinny then its the speakers. sometimes speaker need to be broken in a bit.

hook up your main front left and right speakers to your rear outputs. if you hear the tinnyness then its the output of that channel on the amp or a setting. Newer amps let you change speaker sizes in the menu so that it can change over the crossover for that channel.

Since the left and right speakers sound pretty good, there is no problem with the driver software, the problem is in the sound system itself. be sure to have your sound system be check by a professional technician

Hi, as a retired installer maybe i can suggest a better configuration. I would run your front speakers in series with your rear mids in low level. Your sound will be alot cleaner. Hppe that helps.

I would recommend running a four channel amplifier using component speakers up front and co-axial speakers in the rear. You can add more speakers up front, but it depends on what you're trying to accomplish in your car. Do you want it louder? Do you want it clearer? Any system will benefit from an amplifier. More power to your speakers will give you better sound because you'll have more accurate control over the speaker cone. This extra power will result in better clarity, not only at high volume, but low volume too.

yes, you have a few options. Chances are, its your amp. 
1st I would test the speakers - find the amp under the back seat, then test which wires go to the front speakers and use a AA battery to check if the speaker pops with those two wires and the battery.  If it does pop, its your amp needing replaced.  You can switch out that infinity amp for an aftermarket one very easy. Just use a testlight, or voltmeter to test the wires, and switch them to a new 4-channel amp.  
if you need the wiring diagram, let me know...and dont forget to rate me! or ask for more help!

I have exactly the same problem - don't work with CDs either, just radio. Just installed the deck yesterday. Help would be appreciated. Have been through the manual front-to-back.

I guess the question you need to ask yourself then is how much money are you willing to spend? If you are looking for a sound quality system then it WILL cost a lot more than a DB all out BASS system. The system that you have picked out isn't a bad one but as with all systems this in only half the story. You will need to have it installed well to get the best from the speakers that you have chosen too. If you want to have the stealth look in the cabin then it's pretty simple, but you will not get the best sound quality or should I say imaging as the OEM locations usually are no good for this.

I would suggest that even though you keep things looking stealthy in the cabin apply sound deadening to the doors as Asian cars are generally quite tinny unlike German cars. This will make a big difference in terms of overall sound quality & help keep out the road noise so you can hear every little detail of your personalised system.