Crossover
Definition
A crossover is a filter network that splits a signal by frequency. Inside a speaker, it sends bass to the woofer and treble to the tweeter. In a system with a subwoofer, a crossover (in the amp, processor, or sub) sets where the mains stop and the sub starts.
Crossovers are described by cutoff frequency (Hz) and slope (dB per octave). Steeper slopes make a sharper split. Shallower slopes overlap more.
In a stereo system
Passive speakers include an internal crossover after the power amplifier. You do not set that network unless you bi-amp or use an external processor.
For a powered sub, set one crossover, not two stacked at the same frequency. If the amp has a dedicated sub out with its own filter, set the sub's knob to bypass, LFE, or maximum so you are not rolling off twice.
The crossover frequency should sit near where the main speakers' frequency response weakens, often 60 to 100 Hz for bookshelves. See the Subwoofer Connection Guide for wiring.
