Sub Woofer Design

[Tom Priore]

Hey, I know its a bit off topic, but I'm building my self a subwoofer for my
stereo. I have the parts laying around and I figured I'd give it a shot. I
was wondering If you guys could give me some opinion on the amplifier
design.

First I'm building a simple op amp based amplifier. I have some 412 chips
laying around, do you think they would be clean enough to use? I'm also
running the original signal though a low pass filter. I'm thinking for
simplicity it will just be a basic first order passive filter, but if I get
bored I think I might make it a active filter and integrate it into the
amp's opamp. How does this sound? What frequency should I uses for the pole?

Tom