Abstract: An example apparatus includes an output jack including a ground pole and a power output pole, a power supply circuit configured to generate a power signal, a coupler circuit operably coupled to the ground pole and the power output pole of the output jack, such that the coupler circuit is configured to couple the power signal with a noise signal on the ground pole to generate a combined output signal on the power output pole.

Abstract: An example apparatus includes an output jack including a ground pole and a power output pole, a power supply circuit configured to generate a power signal, a coupler circuit operably coupled to the ground pole and the power output pole of the output jack, such that the coupler circuit is configured to couple the power signal with a noise signal on the ground pole to generate a combined output signal on the power output pole.

Abstract: In a switched-power amplifier that has controlled power supply rails, e.g., when a volume control is implemented by varying the power supply voltages, a rate-controlled power supply control circuit eliminates audible pops that would otherwise occur when a change in input level causes the power supply rail voltages to change. The control circuit generates control signals that control the regulators providing the power supply rails with a controlled rate of change such that asymmetry between the voltages of the power supply rail outputs during changes of the power supply rails is substantially reduced. The controlled rate of change is less than or equal to the slowest rate of change of the power supply outputs that supply the power supply rails of the switched-power amplifier.