Abstract: A solid state amplifier for emulating the compression associated with an overbiased class-B push-pull tube amplifier at high input signal levels due to the flow of current into the grid of the output tubes resulting in a desirable output clipping characteristic with crossover distortion is disclosed. The invention includes at least one pair of class-B connected solid state devices, each having an input circuit and an output circuit. The output circuits are connected for mixing. A biasing element in the input circuit of each paired solid state device establishes a clipping level offset at the input circuit and at the output circuit of each device. A clipping element in the input circuit and the output circuit clips the offset at the input circuit and clips the offset at the output circuit of each respective solid state device. A charging element overbiases the offset in the input circuit whenever the input signal is greater than the input clipping element.

Abstract: A clipping circuit is coupled across the bass feedback shunt capacitor in an amplifier circuit to effectively reduce only high level bass signals while allowing level high frequencies to pass and allowing full boost to low level, low frequency signals.

Abstract: The guitar is formed with a guitar body, a neck and a connector securing the neck and body together. The body and the connector have trailing edge portions which lie at an angle to the guitar axis and sweep rearwardly for providing a contoured area behind the neck to thereby facilitate access to the higher fret notes. In one embodiment, the connector is an extruded aluminum member having an upwardly projecting neck flange that is visible from the front adding a decorative effect.

Abstract: An amplifier switchably operative in a plurality of voltage modes depending upon the level of the input signal is disclosed. A circuit for each voltage mode includes a common driver for each level and a plurality of output devices arranged in parallel. Each output device is operative at a selected voltage level and is coupled to the common driver for the corresponding voltage mode. One output device of each level is coupled in series to an output device of the next lower level. A switching diode circuit is coupled between series connected outputs of each output device. In one embodiment, paired diodes are coupled to each level in a common terminal of the diodes are coupled to the input. A regulator is provided for causing the driver and the output devices of each next higher level to turn on prior to the input signal achieving a selected voltage level. The circuit thus provides smooth switching between levels with reduced distortion.

Abstract: In a particular embodiment, an audio amplifier drives a load in the form of a sound producing loud speaker exhibiting a frequency variable impedance characteristic over a range of audio frequencies. Voltage and current feedback circuits respectively establish a minimum voltage feedback and a feedback characteristic representative of the load. A presence feedback circuit couples the voltage feedback circuit to ground for reducing feedback with increasing frequency above a selected level whereby the damping factor of the amplifier is reduced. A resonance feedback circuit coupled in parallel with the voltage feedback circuit reduces voltage feedback with decreasing frequencies below the selected level whereby the damping factor is accordingly reduced. The amplifier is responsive to the reduced damping factor for increasing power to the load for enhancing the sound produced by the loud speaker.

Abstract: The present invention employs gain compensation such that when the amplifier is in the clean mode, the gain is at a selected level and when the amplifier is in the lead mode gain is decreased. In one embodiment a selectable brightness control is employed to raise the high frequency response in the clean mode. In another embodiment, a selectable gain boost control is employed to increase the gain in the lead mode. At least one frequency selectable means is provided in a post distortion stage output circuit for varying the frequency response of the output in the lead mode.

Abstract: An amplifier using vacuum tubes is mounted in a housing with a speaker in such a way as to minimize microphonics by having the speaker axis and all vacuum tube axes parallel.

Abstract: A linear display device provides a floating bar type of display for instantaneous peak values and instantaneous average values of an audio signal. Pairs of respective peak and average comparators are coupled to a source of fixed value bias voltages. The comparators produce outputs when the peak value and the average value of the audio signal exceeds the bias voltage. A logic circuit connected to outputs of each pair of comparators provides an output only when the bias voltage exceeds the instantaneous peak value.

Abstract: A microphone has a diaphragm having a dome central portion being formed of laminate of a thin layer of synthetic resinous material and a thin wire mesh contacting the central portion. As surrounding attachment portion is provided so that the diaphragm is free to vibrate in a plane perpendicular to itself. An annular voice coil is attached to and circumscribes the central portion on the concave side of the diaphragm and a fixed permanent magnet is disposed within the voice coil. The magnet is formed of neodymium iron-boron and the voice coil has an internal diameter greater than its thickness and the thickness of the magnet is greater than the thickness of the voice coil. A method of forming the described microphone is also set forth.

Abstract: Separate audio amplifier channels are provided with separate input signal level controls so that the output of one channel is unaffected by the input signal level of the other channel, and vice versa. A switch controls selection of the desired channel. Three channels also be provided and first and second switches control selection of any one of the three channels. As before, separate input signal level controls are provided for the three channels so that each is unaffected by the signal level control of either of the others. Two channels may be distortion channels, each with an input level control and also with an output level control. One channel may be a clean sound channel.

Abstract: In a digitally controlled amplifier circuit a dc power source is modulated by an oscillator signal for producing a reference square wave signal. A sawtooth signal, double the frequency of the reference signal and synchronized therewith, is compared with a variable input signal to be amplified. When the sawtooth exceeds the input signal a phase shifted version of the reference signal, shifted in phase in accord with the instantaneous amplitude of the variable signal is produced. A switching circuit logically governed by the reference and phase shifted signals produce a pulse width modulated output signal of a selected polarity. An output filter smooths the pulse width modulated output signal and steering diodes control the polarity of the switching circuit.

Abstract: A gated multi-channel amplifier system comprises a plurality of musical performance amplification channel means each responsive only to high threshold level sound input for producing amplified sound output, and another channel comprising a vocal/announcer amplifier channel means capable of responding to announcer sound input of both low threshold level and high threshold level for producing an amplified announcer sound output, and means for gating the vocal/announcer amplification channel means to respond to announcer sound input of low threshold signal level only in the absence of response by the other musical performance amplification channel means.

Abstract: Separate audio amplifier channels are provided with separate input signal level controls so that the output of one channel is unaffected by the the input signal level of the other channel, and vice versa. A switch controls selection of the desired channel. Three channels may also be provided and first and second switches control selection of any one of the three channels. As before, separate input signal level controls are provided for the three channels so that each is unaffected by the signal level control of either of the others. Two channels may be distortion channels, each with an input level control and also with an output level control. One channel may be a clean sound channel.

Abstract: A digital amplifier having a modulator for transforming the analog audio input signal into two complimentary trains of pulse width modulated signals for driving the power switches, which modulator utilizes a precision triangular waveform to control the transformation. The modulator employs all differential processing without saturated transistors to achieve a minimal distortion modulation system. Upon the occurrence of overmodulation, pulses from the width modulated pulse train produced by the modulator are dropped, and the resulting loss of pulses is detected and fed back to a variable gain amplifier stage of the system. The distortion detection system for detecting the missing pulses utilizes a timing network to establish the missing pulse period necessary to begin input attenuation of the audio signal by the variable gain amplifier stage.