Circuit quality quite a crossover frequencies between 250Hz 25Hz circuit board on the opamp 4558 setting can be made. Proteus ares of project drawings are printed circuit boards. Subwoofer Crossover @ ahmedyerli of circuit and PCB design
About 25Hz to 250Hz Bass Crossover circuit;
Half-BASS AUDIO-FREQUENCY-PHASE HIGH BOOTS-PASS / LOW PASS settings can do. 25-250Hz Crossover published under the improved version of the circuit I have. Bass part is very effective, especially boots. If your amp speaker with a normal B switch this setting if you are trying amplified and filtered high pass crossover section comes into play.
Although the circuit raise the amount of noise has very low distortion rate. I’m completely design your own circuit. If you want a quality sound or bass would definitely recommend …