Car Stereos: Subs, jeep grand cherokee, load impedance

Question
I have a 98 jeep grand cherokee and I have replaced the head unit in it and would like to install subs.  Can I use the factory amp to hook the subs to and what would be the best way to do it.  The system sounds damn good like it is but I would like to add a little more to it without having to purchase a new amp.  I already have the subs, they are just sitting in the garage so it would be cool if I could use them.  Thanks in advance.

Answer
Hi Terry,

In theory, you could connect your subwoofers to the factory amplifier's rear speaker outputs; but you'd need to disconnect the existing rear speakers to do this safely.  If you just add the subs to the factory speaker wires without disconnecting the speakers, you'll reduce the load impedance, which could result in damage to the amplifier.

Even with the rear speakers disconnected, I wouldn't expect very good sound quality with this type of setup.  First of all, the factory amp output is relatively low power for a subwoofer.  Additionally, it will make your subs play a full-range audio signal instead of just the deep bass.  This is likely to make the music sound somewhat muddy.

Your best option, by far, would be to purchase a separate amplifier for your subwoofers.  You don't necessarily need to use both your subs; if you're just looking for some low-end reinforcement, you'll probably get good results with a single subwoofer.   This might allow you to purchase a less expensive amplifier, as well as leaving you more cargo space.

Hope this helps!

Brian