Fuhjythy 400W Speaker Crossover 2 Way High-Low 4-16 Ohm Frequency Divider for Speaker

Jumper A, B are used to control audio effect of bass range. A for lower limit while B for upper limit of the bass audio range. For some speakers, when Bass is turned up too much, the speaker show distortion. When that happens: we remove the jumper cap of jumper A to limit super low Bass to bring distortion lower. When we remove the cap of jumper B, Bass is increased while cap of Jumper B is on, Bass is decreased. Jumper C and D are used to control Treble range. When cap of both jumper C and D are on, the sound of treble is loudest. When only cap C is on, the treble sound is lower. When only cap D is on, further lower. When both caps of C and D are removed, there is no treble sound. (Generally speaking, with the four , you'd sooner or later find your best sound effect. Anywya, all effects still depend on your actual test.)