subs possible?

[mastaofdisasta]

The way my car audio is set up now is an alpine amp infinity 3.5s in the front and alpine 6x9 in the back, The back speakers are set up to only put out bass, theoretically cant i just hook up a sub to the back speakers instaead of the speakers themselves.

[GraniteLXI]

You could hook up subs to the back speakers...but my question is can you power them? Do you have an amp powering your rear speakers only or all 4? 6x9's dont take a lot to power (mostly, there are some crazy ones out there, such as 900 watt Vulfenhag's lol) But in your case if you hooked up subs to a 2 channel amp you would get much deeper bass and better response then 6x9's, and you wont lose any treble since your current set up is lacking treble in the rear.
-To sum it up id say yeah, go for it, just keep in mind you will have to adjust a few things so the subs dont drown out the music lol

[AccordB20A]

yeah if u are using an amplifier with the low pass on you should be able to power sub woofers off it

[KWoodRacer]

The way my car audio is set up now is an alpine amp infinity 3.5s in the front and alpine 6x9 in the back, The back speakers are set up to only put out bass, theoretically cant i just hook up a sub to the back speakers instaead of the speakers themselves.

In my opinion you will get a much better bass response if you power the sub through a amp. My reason being is that if you want bass that will rattle you, you need to have a bigger gauge wire than just a sub hooked up through a rear speaker. Go to walmart and pick up a wiring kit and its just simple from there on out. That is just my opinion. If you need any walk troughs or help on wiring just let me know and I will be more than happy to help you.