Replacement Passive Crossover Yamaha S215V 6Dual 15" Club Series Speakers & Horn 653753250675 | eBay
Amazon.com: Audiotek -CX2-300 Watts Maximum Power 2 Way 4 Ohm Car Audio Passive Crossover Networks/High and Low Frequency Response/Crossover- 3500 kHz (Pack of 2) : Electronics
Passive Crossover Network | Doogesound 3 Way Crossover | 3 Way crossover network kit - YouTube
Digital Crossover basics
AHUJA - Professional 2-Way Passive Crossover Network. Designed for use with 2 nos. LF woofer AHUJA Model L15-MB500 or L12-MB650. HF driver CDH-1000. PTC for HF protection. High power and Low resistance