Subwoofer circuit (computer)

I've got a 5 inch computer subwoofer I salvaged from an old project and I want to use it with another computer speaker system that has no subwoofer in it. These speakers have a powered preamp and what I am invisioning is running the computer speaker out into a splitter, where the signal goes out separately to both the fullrange speakers and to the sub. What I need is a ciruit to drive the sub. Do any of you know of anything suitable? I've looked around but havn't really been able to find anything.

Also, do i need to filter the signal to separate the appropriate frequencies to send to speaker and sub, or just split it and send the plain signal to speaker pre, and sub circuit?

Thanks for any help,
Michael
 
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the sub enclosure: you could go the way of boom boom and build a bandpass box (which does some filtering) as well as build a small passive crossover.

i think you'd want to split the signal line before it gets to the speaker that does the amp'ing. like get an 1/8th in phono jack-splitter at radio shak, and plug the lead to your speakers in one socket, and your new experimental lead to the sub in the other.

you still need an amp.

search the amps forum for a cheap op-amp mini amp you can build (ie: 10watts bridged should be fine for starters)

good luck.