Abstract: A microphone adapter connects to and receives analog audio input from a microphone and an external music source, such as a smart phone. The microphone audio input signal and external music audio input signal are converted to digital signals and multiplexed into a digital wireless signal that may be transmitted directly to multiple speakers. The digital wireless signals are uncompressed, high definition digital audio signals transmitted in the 2.4 GHz band with a range of several hundred feet. The microphone adapter enables user to easily establish a pop-up public address system without the need for speaker cables, sound boards, mixers, and the like.

Abstract: Loudspeakers optimized for use in array environments are described herein. In one embodiment, a system includes a transducer-array module having a plurality of piston-based transducers. Each transducer is configured to drive a particular one of a plurality of discrete non-concentric acoustic-radiating diaphragms. A frame is positioned around an outermost boundary of a plurality of the discrete non-concentric acoustic-radiating diaphragms, which are adjacent to the outermost boundary. The transducer-array module may be used in array configurations, including, but not necessarily limited to: line, planar, and phased arrays.

Abstract: A theft-resistant audio system for a vehicle including a housing or chassis enclosing a digitally-controlled audio signal source and microprocessor-based controller therefor which is securely and permanently mounted to the vehicle behind the dashboard, and a user interface unit containing manual input controls and an audio system status display which is pluggable into the front of the permanently secured housing through an opening in the dashboard to facilitate removal thereof when the vehicle is unattended to thereby render the audio system unusable and hence of little value to a potential thief.

Abstract: The signal from the crossover network of an audio output circuit is applied to certain of the audio system's low, middle and high frequency speakers through particular compensation circuits that are associated with the crossover network and the speaker driver coils. These compensation networks include: a resistor-inductor-capacitor sequence of selected values connected across the terminals of a high frequency or other driver whose resonant impedance peak must be compensated to a resistive impedance for optimum crossover; a resistor-capacitor sequence of selected values connected across the terminals of a low frequency or other driver whose inductance must be compensated to a resistive impedance for optimum crossover; and a variable inductor connected in series with one or more of the terminals of any driver where a "roll off" at higher frequency may be desired. The result is more faithful audio reproduction.

Abstract: A fully passive frequency contouring amplifier using segregated passive networks to shape the different portions of the signal thus avoiding all phase distortion and permitting the stages to be coupled without coupling capacitors, thus avoiding distortion caused by the nonlinearities of capacitors. In addition, a special DC servo loop is used to drastically reduce DC amplification.