Abstract: A portable audio device that includes a motion sensor, an audio equalizer, a speaker, and a context detector. The motion sensor detects general motion, movement, or acceleration of the device and outputs a series of momentary measurements. The context detector receives these momentary measurements and determines whether the portable audio device is being held in the hand of a user. Upon determining that the device is being held in the hand of user, the audio equalizer performs upward tilt equalization on an audio signal being played by the device through the speaker. Upon determining that the device is not being held in the hand of user (e.g. it is lying flat and still on a surface), the audio equalizer performs downward tilt equalization on the audio signal. Other embodiments are also described.

Abstract: A portable audio device that includes a motion sensor, an audio equalizer, a speaker, and a context detector. The motion sensor detects general motion, movement, or acceleration of the device and outputs a series of momentary measurements. The context detector receives these momentary measurements and determines whether the portable audio device is being held in the hand of a user. Upon determining that the device is being held in the hand of user, the audio equalizer performs upward tilt equalization on an audio signal being played by the device through the speaker. Upon determining that the device is not being held in the hand of user (e.g. it is lying flat and still on a surface), the audio equalizer performs downward tilt equalization on the audio signal. Other embodiments are also described.

Abstract: A phonograph preamplifier network with infrasonic cutoff response. In one form, the preamplifier network is a single stage active filter configuration with a high gain, high input impedance differential amplifier provided with an RIAA equalization feedback filter network coupled between the amplifier output and inverting input. An RC filter network is coupled between the inverting amplifier input and ground potential to provide a single, low frequency real axis pole. In addition, an input filter feedback network is coupled between the preamplifier input terminal and the non-inverting input of the amplifier, and further boot-strapped to the amplifier inverting input. The network provides a pair of low frequency off-axis complex poles.

Abstract: A phonograph preamplifier network with infrasonic cutoff response. The preamplifier network is an active filter configuration with a high gain, high input impedance differential amplifier provided with an RIAA equalization feedback filter network coupled between the amplifier output and inverting input. An RC filter network is coupled between the inverting amplifier input and ground potential to provide a single, low frequency real axis pole. In addition, an input filter feedback network is coupled between the preamplifier input terminal and the non-inverting input of the amplifier, and further bootstrapped to the amplifier inverting input. The network provides a pair of low frequency off-axis complex poles.