Diy subwoofer controller circuit (Home Theatre)

Hi Guys.
I have been building a new plate amp for my hifi subwoofer. Its uses a ported box (not sealed) with a 12'' LF driver.
I have been meaning to build an appropriate controller (low pass filter) with volume, freq and phase switch.
I have come up with the following circuit. Most of it is partially copied from a Sony sub woofer schematic that I have,
Will this circuit work??
What are the changes you would make?
Are there any better circuits I could use.
There isn't any reputable schematics online that people have built and tested except for Rod Elliott's P48, but it needs a special box and driver.
Any help will be much appreciated.

The centre section at the top appears to be a high pass filter & if my mental calculations are correct, at way above subwoofer frequencies?
The filter at the top right is a pretty common design, but most seems to use rather larger caps - eg. 0.4 or 0.47 feedback and 0.22 to ground.

ps. Be sure to avoid ceramic caps in the audio path - they can cause serious distortion in some applications.

R Jenkins is correct.
I simulated your highpass filter. It attenuates all bass frequencies!
Don't you want 20Hz to rattle your windows and shake your bones?
Increase the resistor values but do not operate a ported woofer below its cutoff frequency.

Are you using a subwoofer output signal for your signal to the subwoofer or the two stereo signals?

The receiver subwoofer-out signal does not normally need a variable low-pass filter as it is already filtered.
If so, all you may need is a gain pot, and an inverting amplifier for the phase-reversal switch.