Abstract: The present invention features a high-quality audio frequency loudspeaker system utilizing an array of tweeters placed in vertical alignment along an axis. The tweeter array, containing a plurality of tweeters, is mounted on a tweeter baffle board which may be reoriented by a user, so that the speaker system may be positioned in either a horizontal or a vertical orientation relative to the floor or other supporting surface. Reorientation of the tweeter array, in conjunction with other novel features, allows the speaker system to meet horizontal and vertical radiation pattern specifications for home theaters.

Abstract: The present invention features a dynamic speaker having improved output power and decreased second harmonic distortion. The reduction in second harmonic distortion results from a sandwich-type shielding arranged about the stepped pole piece of the speaker. The shielding protects the voice coil from a non-symmetrical magnetic flux interaction with the air gap between the pole piece and the front plate. This reduces the second harmonic distortion due to the non-symmetry of the minor hysteresis loop formed by the magnetic field of the energized voice coil with the static magnetic field acting on the ferromagnetic material making up the pole piece. Additionally, the decrease in inductance due to the location of the nonferromagnetic shielding members produces an increase in output.

Abstract: A stereo speaker system adapted for home use is arranged to increase stereo image perception by reducing spurious and confusing sound images. The speaker system includes a pair of low frequency speaker assemblies and a pair of high frequency speaker assemblies. The pair of low frequency speaker assemblies can be constructed along conventional lines although a columnar arrangement of speakers or acoustic transducers is preferred and preferably arranged to handle acoustic energy in a frequency range below 1000 Hz. The remaining portion of the speaker system includes a pair of high frequency speaker assemblies. Each assembly consists of a single column arrangement of a plurality of acoustic transducers or speakers; in one preferred embodiment, 24 high frequency speakers are included.

Abstract: A safety control mechanism for a press brake assembly or the like, wherein an operator is required to continuously depress two hand control buttons to initiate movement of a ram from a top dead center position toward the workpiece. When the ram has come within a predetermined distance of a support die on which the workpiece is positioned, a foot pedal is actuable for controlling movement of the ram during actual contact with the workpiece and until the ram reaches top dead center. The operator is then free to grasp and position the workpiece during the actual work operation.

Abstract: An integrated circuit stereo decoder includes a blend control input terminal. The DC control voltage on this input terminal determines channel separation. During multiplex FM reception of multi-path signals, the signal strength signal has AM and a DC components. By detecting and amplifying the AC component and adding it to the DC component of the signal strength signal, in phase opposition, the presence of multi-path can be made to reduce the resulting combined signal strength signals which, in turn, is connected to the blend control terminal. Accordingly, the presence of multi-path reduces separation to maintain signal to noise ratio and reduce distortion.

Abstract: A system for deriving a voltage which is a logarithmic function of peak value of an audio signal, in which the audio input signal is amplified by means of an operational amplifier having bipolar feedbacks through a pair of oppositely poled rectifying junction devices operating over logarithmic portions of their response characteristics, the output of the operational amplifier being applied in opposite polarities to a second pair of rectifying junction devices to rectify a bipolar signal applied thereto, and to control current flow to a storage capacitor, the second pair of devices having a common load which provides a constant current source for slow charge of the storage capacitor in one sense, the second pair of devices providing rapid discharge paths in the opposite sense. In one embodiment either or both pairs of rectifying junction devices can be transistors.

Abstract: A gain control or multiplier circuit in which an ac signal is applied through bipolar diodes having logarithmic response characteristics to the bases of bipolar transistors connected in series and having an output at their junction, the diodes being directly cross connected to the bases, and gain control signals of opposite polarities being applied to the bases, thereby providing a linear output from the transistors despite their non-linear response characteristics.

Abstract: A cathode ray tube meter, which may be developed as a VU meter, provides visual representation of the signal levels in each channel of plural signal channels. The signal channels may be the signal channels in a multi-channel audio system. The amplitude of a sawtooth waveform signal from a sawtooth waveform signal generator, which also controls the vertical sweep of an oscilloscope, is compared sequentially with individual d.c. signals developed by respective peak detectors, one being associated with each signal channel, to provide a control signal whenever the amplitude of the sawtooth waveform signal exceed the level of that particular one of the d.c. signals with which it is being compared at any given time. The control signal thus produced is used either as a blanking signal for the vertical sweep or as a signal for effecting the resetting of the sawtooth wave generator. A second sweep signal having a plurality of discrete levels controls the horizontal sweep of the oscilloscope.

Abstract: A superheterodyne f.m. receiver having a manually tunable local oscillator which is electronically voltage tunable over a small range, and including a frequency discriminator for providing signal voltage and a.f.c. voltage in response to a received f.m. carrier, wherein is provided an electronic bipolar switch responsive to either positive or negative a.f.c. voltage of greater than a predetermined value for effecting grounding of a point of an a.f.c. circuit which applies a.f.c. voltage to the local oscillator, and which also includes an interchannel noise detector which also provides grounding signal for that same point of the a.f.c. circuit.

Abstract: In an amplification system comprising an amplifier, a loudspeaker, normally open contacts connected in series between the amplifier and the speaker, and a power supply for the amplifier having relatively long buildup and decay times of its output voltage in response respectively to the connection and disconnection of the power supply to and from the a.c. line, means are provided responsive to the connection of the power supply to the a.c. line for delaying the closing of the normally open contacts until after the power supply voltage has built up to its full operating potential for eliminating the transient audio signals from the amplifier associated with power supply voltage buildup from being reproduced by the loudspeaker. Means are also provided for opening the contacts quickly after the power supply is disconnected from the a.c. line for eliminating the distorted audio signals from the amplifier associated with power supply decay from being reproduced by the loudspeaker.