Abstract: A computer system having a loudspeaker mounted on a main logic board by a hermetic seal, is disclosed. More particularly, embodiments of the computer system include an acoustic cavity defined between the loudspeaker, the main logic board, and the hermetic seal. Embodiments of the computer system may include a compressible seal separated from the hermetic seal by the loudspeaker and/or the main logic board. The compressible seal may define an acoustic channel and the loudspeaker may emit sound in a high frequency range through the acoustic channel toward a system exit. Other embodiments are also described and claimed.

Abstract: A computer system having a loudspeaker mounted on a main logic board by a hermetic seal, is disclosed. More particularly, embodiments of the computer system include an acoustic cavity defined between the loudspeaker, the main logic board, and the hermetic seal. Embodiments of the computer system may include a compressible seal separated from the hermetic seal by the loudspeaker and/or the main logic board. The compressible seal may define an acoustic channel and the loudspeaker may emit sound in a high frequency range through the acoustic channel toward a system exit. Other embodiments are also described and claimed.

Abstract: A programmed data processor obtains a number of input voltage measurements for a number of speaker drivers, respectively, and a sensed shared current being a measure of current in a single power supply rail that is feeding power to each of a number of audio amplifiers while the audio amplifiers are driving the speaker drivers in accordance with a number of audio channel test signals, respectively. The programmed data processor computes an estimate of electrical input impedance of each of the speaker drivers using the input voltage measurement for the speaker driver and using the sensed shared current. Other embodiments are also described and claimed.

Abstract: A method for operating an audio system having multiple Class D audio amplifiers is described. An external oscillatory signal is coupled to the amplifiers, such that the switching frequencies of both of the amplifiers align with (e.g., are directly set to) a frequency of the external signal. An input level associated with an audio signal that is being amplified is detected, and the detected input level is compared to a threshold. When the comparison indicates that the input level is below a lower threshold, the frequency of the external oscillatory signal is raised, and when the comparison indicates that the input level is above an upper threshold, the frequency of the external oscillatory signal is lowered. Other embodiments are also described and claimed.

Abstract: A programmed data processor receives input voltage measurements for a number of speaker drivers, wherein each of the voltage measurements may be a sensed or estimated sequence of time-domain samples of a respective speaker driver input voltage that is over a different time frame. The processor obtains a sensed shared current, being a measure of current in a single power supply rail that is feeding power to each of a number of audio amplifiers, while the audio amplifiers are driving the speaker drivers in accordance with a number of audio channel signals, respectively. The processor computes an estimate of electrical input impedance for each of the speaker drivers using the sensed shared current and the input voltage measurements. Other embodiments are also described and claimed.

Abstract: A power converter has an output that is coupled in parallel with an energy reservoir circuit and a power supply node of an audio power amplifier. The converter can set an upper limit on its input supply current that is variable in accordance with a control input. A controller is to produce a signal, coupled to the control input of the power converter, that is responsive to a measure of input supply voltage of the power converter and either output voltage of the power converter or output power of the amplifier. Other embodiments are also described and claimed.

Abstract: A method for audio signal processing, where an audio amplifier drives a load through a connector, using 1) an input audio signal, and 2) a signal from a return pin of the connector. Output headroom of the audio amplifier is automatically detected, while the amplifier is driving the load. A variable resistor circuit that is coupled to provide variable resistance between the return pin of the connector and a ground plane, is automatically adjusted, in response to the detected output headroom of the amplifier. Other embodiments are also described and claimed.

Abstract: An audio jack may include two contacts to electrically connect to a ground contact of an audio plug in order to detect that a metallic audio plug is inserted into the audio jack. A first of these two contacts may be grounded to form a current return path that generates a ground voltage at the ground contact of the audio plug. The second of these two contacts may be repurposed after the detection to sense the ground voltage. The sensed ground voltage may be added to right and left audio signals. The net voltages provided to the audio plug may be right and left audio signals that include the sensed ground voltage minus the actual ground voltage at the ground contact of the audio plug. This may remove the ground voltage from the net audio output signals, which may reduce crosstalk.

Abstract: A programmed data processor receives input voltage measurements for a number of speaker drivers, wherein each of the voltage measurements may be a sensed or estimated sequence of time-domain samples of a respective speaker driver input voltage that is over a different time frame. The processor obtains a sensed shared current, being a measure of current in a single power supply rail that is feeding power to each of a number of audio amplifiers, while the audio amplifiers are driving the speaker drivers in accordance with a number of audio channel signals, respectively. The processor computes an estimate of electrical input impedance for each of the speaker drivers using the sensed shared current and the input voltage measurements. Other embodiments are also described and claimed.

Abstract: A programmed data processor obtains a number of input voltage measurements for a number of speaker drivers, respectively, and a sensed shared current being a measure of current in a single power supply rail that is feeding power to each of a number of audio amplifiers while the audio amplifiers are driving the speaker drivers in accordance with a number of audio channel test signals, respectively. The programmed data processor computes an estimate of electrical input impedance of each of the speaker drivers using the input voltage measurement for the speaker driver and using the sensed shared current. Other embodiments are also described and claimed.

Abstract: Circuits, methods, and apparatus for grounding contacts in an audio jack. One example may provide a driver, such as a charge pump, driving a first depletion mode transistor coupled between a first contact in an audio jack and ground, and a second depletion mode transistor coupled between a second contact in the audio jack and ground. The first depletion mode transistor and second depletion mode transistor may be p-channel transistors or n-channel transistors.

Abstract: Circuits, methods, and apparatus for grounding contacts in an audio jack. One example may provide a driver, such as a charge pump, driving a first transistor or switch coupled between a first contact in an audio jack and ground, and a second transistor or switch coupled between a second contact in the audio jack and ground. The first transistor or switch and second transistor or switch may be p-channel transistors or n-channel transistors depletion or enhancement-mode transistors, floating-gate transistors, MEMs, relays, or other switching devices. The first and second transistors or switches may be on and conducting when power is removed from the driver.

Abstract: An audio source device has an audio connector to which an external load can be connected. An audio signal is amplified and then driven through the connector, wherein the amplification process uses feedback from the return pin of the connector. The return pin is directly connected to a ground break resistor circuit. The ground break resistor circuit is connected between the return pin of the audio connector and circuit ground. A determination is made as to whether the connected external load has a low impedance or a high impedance. When a low impedance load is detected, such as a headset, the ground break resistor circuit is essentially short-circuited. When a high impedance load is detected, the ground break resistor circuit is maintained and its value is set in accordance with the detected load. Other embodiments are also described.

Abstract: A power converter has an output that is coupled in parallel with an energy reservoir circuit and a power supply node of an audio power amplifier. The converter can set an upper limit on its input supply current that is variable in accordance with a control input. A controller is to produce a signal, coupled to the control input of the power converter, that is responsive to a measure of input supply voltage of the power converter and either output voltage of the power converter or output power of the amplifier. Other embodiments are also described and claimed.

Abstract: An electronic device having an enclosure having a top panel and a bottom panel. An electromagnet is mounted within the enclosure, the electromagnet having a core portion attached to the top panel and a coil connected to the core portion. An attractor plate is attached to the bottom panel, the attractor plate forming part of a magnetic circuit of the electromagnet such that when an electrical audio signal is applied to the electromagnet, the bottom panel vibrates and produces a sound. A permanent magnet is further attached to the core portion, the permanent magnet is configured to create a bias in the magnetic circuit so as to modify a distortion in the sound.

Abstract: An audio system bus has a bus data line and a bus clock line. Audio producers are coupled to the bus to form a time-division multiplexed multi drop bus interface arrangement having protocol slots 0,1, . . . N where N is an integer greater than two. A bus device is coupled to the bus that produces a) a frame marker on the bus data line in slot 0, and b) a data bit on the bus data line in slot 1. The audio producers are to produce their respective audio data bits in their assigned slots other than slots 0 and 1. Other embodiments are also described and claimed.

Abstract: An electronic device having an enclosure having a top panel and a bottom panel. An electromagnet is mounted within the enclosure, the electromagnet having a core portion attached to the top panel and a coil connected to the core portion. An attractor plate is attached to the bottom panel, the attractor plate forming part of a magnetic circuit of the electromagnet such that when an electrical audio signal is applied to the electromagnet, the bottom panel vibrates and produces a sound. A permanent magnet is further attached to the core portion, the permanent magnet is configured to create a bias in the magnetic circuit so as to modify a distortion in the sound.

Abstract: A multi-channel audio system that can provide a variable sub-sample delay between two or more audio channels. In one embodiment, a variable timing clock generator generates multiple clock signals where each may have different phase, and the clock generator can vary the phase difference, in accordance with a sub-sample delay setting input. These clock signals are used by respective digital-to-analog converters (DACs) to convert the digital audio channels into analog form. In another embodiment, a variable delay block is added to an oversampling DAC, on a per channel basis. Other embodiments are also described and claimed.

Abstract: Audio jack optical modules that may have a reduced size. Various examples may provide an optical module for an audio jack where a driver circuit is omitted from the optical module and instead placed either elsewhere in the audio jack or separately outside the audio jack. In some examples, the driver may be integrated with a logic circuit, such as a coder-decoder (CODEC) or other logic circuit. Other examples may provide an optical module for an audio jack where a lens for a light-emitting diode is omitted. In some examples, a higher-power light-emitting diode may be used. These light-emitting diodes may be strong enough to provide a requisite amount of light to a detector in, or associated with, an audio plug.

Abstract: An audio source device has an audio connector to which an external load can be connected. An audio signal is amplified and then driven through the connector, wherein the amplification process uses feedback from the return pin of the connector. The return pin is directly connected to a ground break resistor circuit. The ground break resistor circuit is connected between the return pin of the audio connector and circuit ground. A determination is made as to whether the connected external load has a low impedance or a high impedance. When a low impedance load is detected, such as a headset, the ground break resistor circuit is essentially short-circuited. When a high impedance load is detected, the ground break resistor circuit is maintained and its value is set in accordance with the detected load. Other embodiments are also described.