The Juice JA1504 4 Channel 1500W Bridgeable Car Amplifier has been designed and engineered to produce a high level of sound quality and performance at an affordable price. The four channel addition to the series is perfect for powering door speakers, 6' x 9' speakers and/or a subwoofer.4 Channel Amplifier.Combining impressive power with big sound for a loud, clear and distortion-free music experience.Variable HPF and LPF.Variable HPF adjusts your high-pass filter frequency for greater audio system flexibility. Variable LPF adjusts your low-pass filter frequency for greater audio system flexibility.