Active crossover how?

I have purchased a amp unit and a sub driver and built a box, my only issue is i think i need a crossover as i need to remove all the high and middle tone and only leave the bass. this is for a DJ speaker with bass bin.

If someone can help with a schematic design for a variable one i would appreciate it.
the details for them both are.

Driver details:
Main Parameters:
Nominal diameter: 15”
Ohms: 8 ohms
Power handling Peak: 400 watts
Power Handling RMS: 200watts
Sensitivity: 96.4 db
Frequency Range: 48-4500hz

Thiele-Small Parameters
Fs 52.8Hz
Re 6.0 Ohms
Sd 34.6 sq.mm
Qms 9.9
Qes 0.60
Qts 0.57
Mms 28.8gr.
BL 9.8 Tm
Xmax +/- 5 mm
Le 0.6mH
Ref 101.6dB"

Amp modual:
Max Power: 400W
Sensitivity: 98dB
Frequency response: 45Hz-20Khz ( -3dB)
Microphone/Line input
Volume control

You could use the UAF42 filter chip. A Butterworth type filter with a 2nd order rolloff should give the desired rolloff. The typical desired cutoff frequency is 80-100Hz. You can use this free program from TI to help with the design.

But the easiest is just to buy one such as this.

Most half-decent 15" woofers have an Fs of 25Hz, not 52.8Hz.
Most half-decent amplifiers go down to 10Hz to 20Hz, not 45Hz.
Put them together and you will not have any deep bass. It will sound like a little 6.5" woofer.

You must see the manufacturer's recommended crossover frequency which will revealed on the frequency response graph that shows a peak somewhere around 3kHz to 5kHz. Your crossover circuit must remove the peak.

It might be better just to buy a subwoofer amp that goes below 45Hz and has a built in filter, such as one of these.