Crossovers for Car Audio - Tune on HEAD UNIT or AMPLIFIER? Or combination? - YouTube
Audio Speaker Subwoofer Crossover Use Press-fit Terminals Audiophile Speaker Crossover Home or Car Sub/Subwoofer - AliExpress
Subwoofer Frequency Setting | Woofer Guy
BOSS Audio Systems BX55 Pre-Amp Electronic Car Crossover – 2-3 Way, Fine Tune Your High-Mid-Low Range Speaker Frequencies, Remote Subwoofer Control Included, Equalizer, DPS Audio Processor
Amazon.com: Banda 3-Way Electronic Car Crossover Two or Three-Way System Set-Ups with Rear Fader Control,Subwoofer Equalizer,2/4/6 Channel Inputs,5V RCA Outputs,Front/Rear/Subwoofer Level Control Banda XVR360 : Electronics