Abstract: A loudspeaker power amplifier comprising a digital amplifier is provided. The amplifier has a negative input and a positive input as well as a negative output and a positive output. The power amplifier further comprises a first feedback circuit from the positive output to the negative input, and a second feedback circuit from the negative output to the positive input. The first and the second feedback circuit each have a first and a second amplification circuit.

Abstract: An electret microphone is provided. This comprises an electrically conductive membrane, and a counter-electrode having at least one first hole having a first distance from an edge of the counter-electrode and a second plurality of second holes each having a second distance from the edge of the counter-electrode. The second distance is shorter than the first distance. The electret microphone has a first electrically conductive coating on a first side of the counter-electrode and a second electrically conductive coating on a second side of the counter-electrode. The at least one first hole comprises a via in order to electrically contact the first and second electrically conductive coating. A third distance is provided in each case between the second holes and the first electrically conductive coating so that the first electrically conductive coating does not reach as far as the second holes.

Abstract: An electret microphone is provided, comprising a microphone capsule with an output connection, a first input connection as an earth connection and a second input connection for providing a supply voltage for the microphone capsule and for leading out a microphone output signal of the microphone capsule, and a cascode consisting of a first and second transistor. An output connection of the microphone capsule is provided as input of the cascode. The second transistor is configured as a field effect transistor FET and the gate connection thereof is coupled to the output connection of the microphone capsule. A drain connection of the second transistor is coupled to an emitter connection of the first transistor as bipolar transistor or to a source connection of the first transistor as an FET transistor. Furthermore, a third transistor is provided as bipolar transistor, whose emitter connection is coupled to the second input connection.

Abstract: Power supply units e.g. in network operated loudspeakers are tailored to peak values that are reached only relatively rarely and then in pulses. With an intermediate storage of electrical energy in an intermediate circuit energy storage element it is possible to provide a significantly higher amount of power at least for a short period of time. The intermediate circuit energy storage element may be a capacitor or accumulator, for example, which is connected to an intermediate circuit voltage that is higher than the input voltage, and that is generated by an upconverter. A downconverter generates the output voltage of the power supply unit from the energy stored in the intermediate circuit storage element. The output voltage of the power supply unit is used as power supply for an audio amplifier. The power supply unit may provide for a short period of time a higher current or more energy respectively than the actual energy source, for example the network node.

Abstract: Power supply units e.g. in network operated loudspeakers are tailored to peak values that are reached only relatively rarely and then in pulses. With an intermediate storage of electrical energy in an intermediate circuit energy storage element it is possible to provide a significantly higher amount of power at least for a short period of time. The intermediate circuit energy storage element may be a capacitor or accumulator, for example, which is connected to an intermediate circuit voltage that is higher than the input voltage, and that is generated by an upconverter. A downconverter generates the output voltage of the power supply unit from the energy stored in the intermediate circuit storage element. The output voltage of the power supply unit is used as power supply for an audio amplifier. The power supply unit may provide for a short period of time a higher current or more energy respectively than the actual energy source, for example the network node.