Subwoofer Wiring Diagrams — How to Wire Your Subs Designed and organized Crutchfield's subwoofer wiring diagrams; I recently bought this JBL GTR 7535 amp along with 2 Club 1224 subwoofers. The subs have a switch which lets you choose between 2 and 4 ohms. which setting should I use? 3) Crossover: What is its function and how should it be set? 4) Gain: Again what is the function and how Speaker Crossover Wiring Guide - DIY Audio & Video DIY Audio Speaker Crossover Wiring Guide / FAQ See the Crossover Example Tutorial for more information. What is a crossover? People can hear sound frequencies from 20-20,000Hz. There is no one speaker capable of producing all frequencies throughout this range.