Active signal processors capture the audio signal before it gets to the amplifier allowing you to modify the waveform to meet your needs. They require external power to operate, but provide a higher degree of adjustability than most amplifier preamps or passive (non powered) devices.
Passive signal processors are a great way to control the frequencies going to speakers when an active processor isn’t an option. Installation is easy since no external power is required and the setup is preconfigured.
