How to set up the Focus audio system?

[Katniss]

Steps for setting up the Focus audio system: 1. Set all volume controls on the head unit to the center position, then increase the volume to 80%, and minimize the amplifier sensitivity. Now, adjust the input gain of the electronic crossover to the middle position, open the amplifier input gain by about one increment, and then increase the output sensitivity of the electronic crossover until the speakers produce distorted sound, then slightly reduce it. 2. Turn off the mid and high frequencies of the front and rear channels, and listen to the subwoofer alone. Adjust the crossover to allow the subwoofer to operate naturally without mechanical noise or excessive bass. Reduce the volume of the rear channels, then test the phase of the subwoofer. At low volume, change the phase of the subwoofer by 180° (positive or negative) or use the 0°-180° selector switch on the electronic crossover to determine which phase produces a louder volume, indicating the correct phase. Once all phases and frequency ranges are set, perform fine-tuning. Generally, the crossover point for the subwoofer is set between 80Hz-100Hz, while the high-pass crossover point for mid and high-frequency speakers is between 60Hz-90Hz.