Amazon.com: Taidacent DC7-15v AC5-12v NE5532 Low Pass Filter Board Deep Bass Output 22HZ-280HZ Frequency Adjustable Single Power Supply Subwoofer Bass Filter Board Can be Used with Tone Board : Electronics
Subwoofer Low Pass Filter Board using NE5532 Op Amp - Easy to Make Hobby Kit | MYPCB
NE5532 Subwoofer Audio Control Preamplifier Low Pass Filter Subwoofer Crossover Frequency Divider Pre-amp Board - AliExpress