Abstract: A loudspeaker with an overlay or bifilar wound split voice coil, a coil for driving a higher frequency speaker such as a tweeter, and a push-pull audio amplifier circuit directly coupled with the coils. The configuration of the split coil provides two coaxial voice coils that produce a transformer coupling at high frequencies. This coupling compensates for the normally experienced increased input impedance at high frequencies and results in a fairly constant input impedance over a large frequency range, facilitating uniform power transfer to the speaker. The high frequency voice coil is coupled across the split coaxial coils and is energized at high frequencies by a combined signal which includes the signal directly applied to one of the coaxial coils and the induced signal in the other coaxial coil.

Abstract: A loudspeaker with an overlay voice coil and directly coupled push-pull audio amplifier circuit is disclosed. The overlay configuration compensates for increased input impedance at high frequencies by introducing a transformer coupling between two co-axial voice coils. The resultant input impedance remains fairly constant over a large frequency range, thereby insuring uniform power transfer to the speaker.

Abstract: An aural-visual display system especially suitable for visually displaying a number of items, such as products, and playing a recorded message relating to a displayed item in response to actuation of a selector corresponding to the item. One of a number of different messages on a magnetic tape are selectively played by changing the positional relationship between a magnetic pickup and the message location on the tape, in response to operation of a selector. This concurrently produces a visual display associated with the selected item to which the message relates.

Abstract: A high-efficiency loudspeaker with a split voice coil and directly coupled push-pull audio amplifier circuit, especially useful when energized through a single-ended, low voltage, external power source to increase the output of a relatively low-power audio amplifier without undue distortion.

Abstract: An aural-visual display system especially suitable for visually displaying a number of items, such as products, and playing a recorded message relating to a displayed item in response to actuation of a selector corresponding to the item. One of a number of different messages on a magnetic tape are selectively played by changing the positional relationship between a magnetic pickup and the message location on the tape, in response to operation of a selector. This concurrently produces a visual display associated with the selected item to which the message relates.