Passive lowpass filter built into the sub?

[Lynx_TWO]

I built an AutoTuba I currently use for home theater, and I realized my Pioneer Elite 92TXH amplifier is cutting frequencies to the sub at around 169 and 149 Hz by 10dB. If I installed a lo-pass filter for 100 Hz in the driver compartment, would this actually be a good thing to do, or just a waste of money? I plan on eventually using the AutoTuba in my car, and building the THT for my home theater needs.

I guess this question would apply for all sub designs. Say, a lowpass for 100 Hz and maybe a highpass for 10 Hz, just to protect the driver...

If this seems sound, what would be the cleanest filter design, or best "bang for buck"?

[Bill Fitzmaurice]

Due to the large component sizes passive filters are unsuited to subwoofer use.

[Haysus]

I tried to go down that road once to help a friend that was not techno savvy with active proccessing. Basically a sub that is plug and play straight from the board weighs 20 more pounds and cost almost twice as much and won't sound any better than doing it right the first time.

My $.02

[Lynx_TWO]

OK then, thanks! Just thought I would ask before doing something potentially bad