Subwoofer controller (Low pass filter)

[K4n0]

Hey all, i built a subwoofer controller which has phase and frequency control from 35 to 150hz.
After building and testing it, im hearing too much of high frequency from the subwoofer. The filter should get rid of most high freqeuncy sounds as its a 24db filter using 2 2nd order filters.
Is there something wrong with the design.
How do i fix this?

 

[K4n0]

I used pretty much the same components as the Schematic apart from the 50k dual pot for frequency control. I used a 10k instead as i didnt have a 50k dual pot.