Audio Wiring / September 8, 2018 / Maggie Pimentel.
Not every car audio crossover operates in the same fashion. Crossovers vary as to the number of frequencies sent to other components of the car audio system. Crossovers also vary as to the rate at which the wavelengths are attenuated or cut. This rate, however, is not fixed. The owner of a car audio system can adjust the speed about which the crossover attenuates or cuts the frequencies that become fed into the power amplifier.
Before you do a parallel hook-up on an amplifier, make sure that the amp can take the ohms load that will result. Find out what ohms load the amplifier is stable at and then choose speakers with the appropriate ohms rating so that the hook-up will ensure that the ohms load is within the capability of the amplifier. Generally speaking, most midrange, midbass, and tweeters you use will be 4-ohm rated. Most subwoofers you use will be 4- or 8-ohm calculated.
Remove the head unit from the dash. You’ll be connecting not only the RCA but also the remote turn on lead. Connect the remote turn on and run it alongside the power wire on the driver’s side all the way into the trunk. Replace the driver’s side carpet and panel. The RCA cables should run down the passenger side.
Speakers come with various ohms ratings. When speakers are connected, the ohms rating, or impedance, of the group of speakers that is wired together changes and affects the ohms load of the amplifier. If you wire two 4-ohm speakers together in a series hook-up, you are producing an ohms load of 8 ohms. If you wire two 8-ohm speakers in parallel, you are creating an ohms load of 4 ohms (8 ohms x 8 ohms divided by 8 ohms + 8 ohms = a 4 ohms load on the amplifier). If you connect two 8-ohm subwoofers in a parallel hook-up to an amp that is bridged mono, the amplifier will see half of the load because it is bridged. So it will see a 2 ohms load.