Abstract: A plurality of a signal peak detection circuits connected in cascade for operation on a complex waveform input signal, for generating a reference signal having peaks occurring in time with the peaks of the fundamental frequency component of the input signal. The reference signal is processed for producing a voltage proportional to the period between successive signal peaks, which voltage is successively stored and monitored at select times for comparison of the relative magnitude changes in the voltage, for updating an output control voltage.

Abstract: A keyboard for a monophonic musical instrument has a plurality of touch sensitive keys which function as variable capacitors, the capacitance depending on the force applied to the keys. The variable capacitance is detected and used to produce a variable control voltage which is used to execute one or several of various control functions, such as controlling the volume of the sound produced by The instrument, controlling the cutoff frequency of a low pass filter in the output system of the instrument, controlling the amount of vibrato or other periodic modulation introduced into the sounds produced by the instrument, controlling the frequency of the vibrato or other periodic modulation, or controlling the amount of "bend" in the pitch of a sound produced by the instrument, i.e. shifting the pitch slightly from its nominal value. The variable capacitors employ a conductive elastomer which is deformed in response to the force applied to the keys.

Abstract: An improved frequency sensitive circuit capable of adjusting one or more of its parameters in order to shunt an adjustable amount of electrical signal to a current sink, thereby controlling the amplitude of the signal. The frequency sensitive circuit is connected to the wiper of a potentiometer that is placed across the inputs of a difference amplifier in order to control the peak value of the cut or boost in the signal. The frequency sensitive circuit includes a shunt impedance connected between the wiper of the potentiometer and the current sink. A resonant circuit is connected to the impedance and is tuned to an adjustable resonant frequency. A compensation circuit, such as a difference amplifier referenced to the wiper, couples the output of the resonant circuit to the shunt impedance so that the impedance of the frequency sensitive circuit approaches infinity as the frequency of the electrical signal is displaced from the resonant frequency.

Abstract: An electronic musical instrument incorporates a single integrated circuit chip for performing a variety of logical operations for the production of chords and various accompaniment signals automatically, in response to depression of one or two keys within a related portion of the keyboard of the instrument. A multiplexer is employed, in association with the keyboard, to produce a train of signals in response to depression of one or more keys, and one or more function control switches; certain ones of these signals are used to address a plurality of read only memory devices for the generation of the several components needed for the mode of operation which is selected. In an automatic chord mode, a chord is selected automatically, corresponding to an operated key of the keyboard. The chord components include the root, the third (which may be selectively minored), the fifth, the sixth and the seventh (which can be selected or not).

Abstract: Improved apparatus for use in an electronic musical instrument having a keyboard including a group of keys corresponding to the notes of a musical scale. Electronic circuitry is used to generate simultaneously with respect to each of the keys first and second electrical tone signals. The circuitry causes the waveshapes of the tone signals to deviate with respect to each other. In addition, the repetition rates of the tone signals are detuned and frequency modulated with respect to each other so that the sound of a string chorus is simulated.The disclosure also describes circuitry useful in an electronic musical instrument having a keyboard including twelve keys corresponding to the twelve notes of a chromatic musical scale. The circuitry generates simultaneously a first series of twelve tone signals corresponding to a first tempered scale and a second series of twelve tone signals corresponding to a second tempered scale different from the first tempered scale.

Abstract: An automatic rhythm generator of an electrical musical instrument including a rhythm pattern generator for rhythmically selecting for actuation different ones of a plurality of instrumentation circuits to be sounded and a strobe pulse generating circuit for establishing the appropriate pulse width of a drive pulse needed by each instrumentation circuit for proper actuation thereof. The rhythm pattern generator circuit selectively enables a plurality of drive gates respectively associated with the plurality of instrumentation circuits during selected ones of a succession of periodic rhythm cycles in accordance with a predetermined rhythm pattern. The strobe circuit is synchronized with the rhythm pattern generator and generates during each rhythm cycle a plurality of strobe pulses on a corresponding plurality of outputs respectively associated with the plurality of instrumentation circuits. Each of the strobe pulses has a width preselected for the instrumentation circuit with which it is associated.

Abstract: An encoder providing on a single terminal of a circuit package a composite serial data stream containing both stored data bits of a multistage binary memory and a clock signal needed for decoding the data. A parallel to serial converter serially shifts the stored binary data bits to an output thereof in response to clock pulses of an internal clock, and a logic circuit responsive to both the internal clock and the serial binary data from the converter generates first, second and third signals of amplitudes discernibly different from one another respectively in response to 1-state data bits, 0-state data bits and the termination of clock pulses. Two fixed inputs to the converter respectively provide a 1-state start bit at the beginning of the set of data bits and a 0-state stop bit at the end of the set of data bits for purposes of decoding. An amplitude discriminating decoder uses the periodic third signals and the start and stop bits to decode the serial data.

Abstract: In an audio amplifier for amplifying signals from an electric guitar or the like having a conventional tone control circuit for selectively emphasizing input signals in the bass, middle and treble frequency ranges of the instrument, a multifilter circuit for emphasizing input signals with frequencies in selected, relatively narrow, frequency bands in the upper portion of the frequency spectrum to minimize aural fatigue. The multifilter circuit comprises a plurality of parallel connected, two-pole, resonant filter sections with different, relatively narrow, resonant frequency bands separated from one another by an amount on the order of 1/4 octave and forms a signal path that supplements the signal path provided by the conventional tone control circuit. The signals produced on the output of the tone control circuit are mixed with the multifilter output signals.

Abstract: A sound effect circuit with a phase shifter producing a signal shifted in phase with respect to an input signal, a combining circuit for arithmetically combining the input and phase shifted signals to produce an output signal, an oscillator for periodically modulating a characteristic frequency of the phase shifter and a modulation control circuit. The modulation control circuit causes the modulation rate to gradually increase when modulation is manually switched on and to gradually decrease when modulation is switched off. The modulation control also causes the characteristic frequency to vary inversely with the modulation rate.

Abstract: An electronic musical instrument has a keyboard equipped with apparatus for developing a voltage in response to the momentum of operated keys of the keyboard, which voltage is employed to control the amplitude of the sounds produced in response to each key depression. The amplitude is dependent partially upon the momentum of the key depression and partially upon the amount of time since the previous depression of the same key. An envelope generator operates in response to depression of a key and has a charge circuit for controlling attack and decay of the envelope. The discharge circuit is controlled partially by the pitch of the note selected by the depression of any given key of the keyboard. The envelope produced by the envelope generator controls a unit which functions as a combined modulator and filter, closing a path between an audio source and an output system and varying the width of the band-pass provided for the signal from the audio source in response to the amplitude of the envelope.

Abstract: A circuit for providing a predetermined contour for the audio signal produced by an electronic musical instrument. A reference potential which is changed under predetermined conditions, and an unidirectional reference current which may also change under some or all of the predetermined conditions, are applied to a circuit which changes the amplitude of the audio signal from its existing level to a level determined by the reference potential at a rate which is determined by the reference current.

Abstract: This invention relates to an improved bracing structure for a stringed musical instrument of the type having lower frequency or bass strings and higher frequency or treble strings, and a bridge through which the strings are coupled to a soundboard structure. The bracing structure is formed on the underside of the soundboard and serves both a mechanical-structural and a mechanical-sonic, or acoustical function. The structural function is to protect the soundboard from damage resulting from the torsional forces resulting from the pull of the strings on the bridge, which forces are transmitted through to the soundboard. This function is accomplished by a torsion bar positioned substantially in axial alignment with the bridge, torsional forces applied by strings to the bridge being transmitted through the soundboard to the torsion bar, and a framing bar structure physically connected to and acting through the torsion bar to distribute the torsional forces from the bridge area of the soundboard.

Abstract: A selection switch memory circuit having a priority encoder for providing a code for the highest priority actuated one of a plurality of momentary contact selection switches, a memory for storing the code and a decoder for providing a select signal on one of a plurality of outputs thereof to activate a circuit corresponding to the stored code. A control includes a comparator to determine if the provided code is the same as the stored code. In one embodiment, if the provided and stored codes are the same, the memory is cleared of the stored code, and the circuit corresponding thereto is deactivated. In another embodiment, the decoder is disabled to terminate activation of the previously selected circuit if the provided and stored codes are the same. In both embodiments, if the provided and stored codes are different, the provided code is entered into the memory in lieu of the stored code. Response of the control to switch actuation is delayed to avoid deleterious effects of switch contact bounce.

Abstract: An electronic synthesizer instrument incorporates bass pedals for the notes of the musical scale, together with foot control apparatus adapted to select and modify the tone quality of sounds produced by operation of the bass pedals. The foot control apparatus includes push button switches which are operated by the toe of an operator's foot, and slide controls which are positioned by the operator's foot. At least some of the switches are preset switches for selecting and controlling multiple combinations of the functional units of the synthesizer. The control state of the instrument is at all times indicated by readily observable indicating lights.

Abstract: A circuit for producing a chorus effect in an electronic musical instrument. The circuit includes N separate channels, where N is an integer greater than one, with each channel having an analog delay line to which a tone signal is applied. Each delay line frequency modulates the applied tone signal at a subaudio rate in response to changes in the frequency of clock pulses applied to the delay lines. The delay variations in one delay line are out of phase with the delay variation in every other delay line by a selected amount which is normally 360.degree./N. Clock pulses are generated by means including a nonlinear circuit to compensate for the nonlinearity in the frequency interval between tones in the musical scale. The outputs from the delay lines after filtering of the clock frequency components are utilized to produce the desired chorus effect output from the instrument.

Abstract: An integrated circuit has a shift register, driven by a source of clock pulses, for sequentially energizing each of a set of selectively activated switches. Each of the switches connects an analog input signal to the input of an individual sample-and-hold unit, the outputs of which are available at output terminals of the circuit. The outputs of the sample-and-hold units represent the amplitude of the analog input signal, sampled at the rate of the clock pulses applied to the shift register. The analog input signals of selected outputs are modified selectively.

Abstract: An electronic musical instrument has a ring oscillator incorporating a multiplicity of identical stages connected to form a ring with the output of each stage being connected to the input of the succeeding stage. Each stage has an RC time constant circuit which introduces a delay in the transmission of a signal from one stage to the next, in accordance with the value of the capacitance of the RC circuit. The capacitance is varied in response to the amount of pressure acting on a key of the keyboard of the musical instrument, and the interval between a succession of pulses presented to an output terminal of the oscillator is dependent upon the force with which the keys are depressed, and the positions within the output pulse train at which such delays are introduced is dependent upon the position of the keys of the keyboard. The output pulse train contains information identifying all of the operated keys of the keyboard and the force with which they are operated.

Abstract: A keyboard of an electronic musical instrument incorporates a plurality of variable capacitors, one for each key, with one conductor of each capacitor being connected for movement with an individual key of the keyboard toward and away from the other conductor, so as to vary the capacitance of the capacitor in accordance with the force with which the key is depressed.

Abstract: This invention relates to an improved neck-body joint for a guitar-like musical instrument which joint minimizes the possibility of relative movement between the neck and body and permits the neck to be pitched at a desired angle relative to the body without weakening either element.