A speaker L pad is a special configuration of Resistors used to control volume while maintaining a constant load Impedance on the output of the audio amplifier. It consists of a parallel and series resistor in an "L" configuration. As one increases in resistance, the other decreases, thus maintaining a constant impedance, at least in one direction. In loudspeakers it is only necessary to maintain impedance to the crossover; this avoids shifting the crossover point.