High Pass Car Audio Filter. The AC source is your sound frequency the switch will change your sound frequency from Bass (100Hz) to Treble (30kHz) you will notice the bass being blocked and the treble being allowed to "pass" to the "speaker" the speaker is the 4 ohm resistor connected to the volt meter. The lamp is in the circuit to absorb extra power when the amplifier drives the tweeter with too much power. (You can see this by increasing the amplitude at the AC source) The real crossover also includes a PTC (poly switch resetable fuse) in series with the positive output to the speaker, which is not included in EveryCircuit.
