How to drive a sub woofer in addition to satelite speakers

[ioncore]

My Polk Audio 2.1 Speaker system broke down. The stereo speakers are in perfect condition, and so is the sub woofer. For some reason, the sub woofer is working fine, yet there is no sound from either of the stereo speakers -- but when I test those separately (by plugging in the jack into a MP3 player), they're working fine.

I opened it up thinking maybe I could spot a burnt out capacitor/resistor/etc and replace it, however the entire circuit is in original condition and nothing seems to (visually) be out of place.

Thinking maybe it is the pre-amps/power-amp that got shot internally, (and for what it's worth a good learning opportunity) I'm thinking about rebuilding the entire amplifier from the ground up -- nothing fancy, just very very crude/basic. I've been searching up on the various types of amplifier chips and found the TDA2009A at the local electronic store. The data sheet offers a good schema of a basic amplifier and I think I'll implement that.

(A cleaner version is here: http://img190.imageshack.us/img190/2226/amplifiere.png )

Now the problem is, the amplifier will be capable of driving the stereo speakers, but what do I do about the sub woofer? The sub woofer has a resistance of 4ohms, the stereo speakers are reading somewhere between 3 and 4. Is there a circuit I could build to drive the woofer from the same input? Or some how augment the above schematics to allow for the woofer?

Just some FYI: The original circuit was driven by a LA4485 and a bunch of C4570ha.

As you can tell I'm very new to this stuff, but have some elementary exposure to electronics. Any help or pointers would be greatly appreciated.

Thanks.

[tedmich]

check out the swift amps at Partsexpress, quite cheap and decent class D amps

2x15W @ 4 Ohm TA2024 Class-D Audio Amplifier Board 320-308

you could just sub in this amp (plus a power supply) into the polk, since the sub works. The 2.1 system likely has a "summing" circuit to feed low freq. from both left and right channels to sub and the "mains" speakers got full frequency.

This unit (backordered) would do the whole deal but is a bit too big

http://www.parts-express.com/pe/show...number=300-773

[J M Fahey]

Your woofer works, so its amplifier works (you just said so)
Your satellites work, their amplifiers too. (you just said so)
Building new amplifiers is a non solution because thatīs not the problem.
I *think* (I have to guess) that your woofer has an internal crossover which keeps the bass and sends mids+highs to the satellites.
Is that so?
In that case, thereīs your real problem.
Please confirm.

*Maybe* you only have a *cable/connector* problem.