1.This BT-218 crossover is to solve the problem of head-booming. It solves the problem of bass head-booming by connecting a large capacitor in series after the bass inductor. 2. The crossover is composed of an inductor coil and a capacitor. The inductor will alleviate the direct current of the power amplifier to the speaker and filter out the interference of ultra-high frequency. 3. The inductive reactance will enhance the bass strength, and cooperate with 2 capacitors to filter out the signal below 70Hz of the power amplifier speaker beyond the limit range, so that the bass is purer, the strength is enhanced and the resonance head-booming problem is solved. 4. There are 2 capacitors on the treble line, and the capacity can be controlled by the switch, so that the sound details are richer and the frequency requirements suitable for oneself are achieved. 5. It is recommended to choose some better fever songs during installation, listen to more songs, and debug the effect through the switch inside. Only by trying more can you get the best effect. Model: BT-218 Filter: 1 high and 1 low (two-way frequency division) Frequency response: about 70Hz - 20kHz Frequency point: about 2650Hz - 2700Hz (adjustable) Applicable impedance: 4 - 8Ω Power handling: 150W Applicable: DIY modification and upgrade of bookshelf speakers Due to different batches, there may be differences in product appearance and printed text, which will not affect use Colour:As Shown Material:PC+Metal Package Contents: 1 x Audio crossover