Abstract: A method enables a musician to reduce the voltage level between a nominal level which is supplied to power an audio power amplifier including at least one vacuum tube power output device and a reduced level, by controlling AC input voltage level of an AC to DC power supply via an input transformer having a primary winding connected to receive nominal AC voltage from the AC power mains, a high voltage secondary, and a low voltage secondary for directly supplying heater power to the vacuum tube power output device.

Abstract: A vacuum tube amplifying apparatus provides predetermined varying dynamic response characteristics in order to enhance the playing characteristics of musical instruments, especially guitar.

Abstract: A preamplifier circuit for enhancing sound generated by a musical instrument such as a guitar and which is converted into electrical signals includes an input, a passive high impedance input network connected to the input, a first preamplifier connected to the passive input network for non-distortion amplification of the electrical signals in a first mode of operation and for saturation distortion amplification of said electrical signals in a second mode of operation. A switch circuit enables switching between the first and second modes of operation. An overdrive amplifier bridges across the passive input network in response to the switch circuit for overdriving the first preamplifier thereby to cause saturation distortion amplification of the electrical signals. A shunt network may be switched across the output terminal to equalize output amplitude of the preamplifier circuit between the first and second modes of operation.

Abstract: An electronic amplifying apparatus intended for sound reproduction and for music instrument amplification wherein two parallel amplifiers, working simultaneously, each in a different class of operation, are fed from a single driver or signal source and whose outputs are combined. In the preferred embodiment at least two pairs of push-pull vacuum tubes are required and they are arranged so that one pair operates Triode Class A while the other pair (or pairs) operates Pentode Class AB (or Class B). The circuit can then be optimized so that the desirable sonic characteristics of Class A Triode operation are imparted into the Class AB (or Class B) Pentodes which actually produce all or nearly all of the power. The output power waveform has the high power and efficiency typical of Class AB (or Class B) Pentode operation but without the detrimental sonic side effects, namely, there is the complete absence of crossover or "notch" distortion, and there is a "soft" gradual onset of clip.

Abstract: An electronic amplifying apparatus intended for sound reproduction and for music instrument amplification wherein two parallel amplifiers, working simultaneously, each in a different class of operation, are fed from a single driver or signal source and whose outputs are combined. In the preferred embodiment at least two pairs of push-pull vacuum tubes are required and they are arranged so that one pair operates Triode Class A while the other pair (or pairs) operates Pentode Class AB (or Class B). The circuit can then be optimized so that the desirable sonic characteristics of Class A Triode operation are imparted into the Class AB (or Class B) Pentodes which actually produce all or nearly all of the power. The output power waveform has the high power and efficiency typical of Class AB (or Class B) Pentode operation but without the detrimental sonic side effects, namely, there is the complete absence of crossover or "notch" distortion, and there is a "soft" gradual onset of clip.

Abstract: An improved associative memory employs plural separately addressable memories, e.g., random access memories (RAM's), which may be written into, or read from in conventional fashion. In a recognition mode, information is read from differing memory locations, and compared with an operand supplied on a data bus by a central processing unit (CPU), comparator apparatus being common for an array of storage locations. The comparison results, determined in accordance with a CPU-specified criterion, are then communicated back to the processor.In accordance with specific aspects of the present invention, masking and/or multiwrite features are provided to permit bit reading/writing/searching, rapid memory writing, to facilitate logical and arithmetic data processing and the like.

Abstract: An electronic amplifying apparatus intended for electric music instruments (primarily guitar), with switchable circuitry offering an improved, specialized circuit for the enhancement of solo playing in addition to customary simple amplification. In the lead (or solo) mode of operation, the circuit will synthesize particular sustain and distortion characteristics and add them to the tone of the instrument (guitar, electric piano, microphone, etc.) to produce a more flexible and expressive sound for solo playing than the sound of the instrument normally amplified. Switching and control circuitry enable the musician to return to a conventional amplified tone which would be preferred for rhythm (or chordal) playing.

Abstract: An improved associative memory employs plural separately addressable memories, e.g., random access memories (RAMs), which may be written into, or read from in conventional fashion. In a recognition mode, information is sequentially read from differing memory locations, and compared with an operand supplied on a data bus by a central processing unit (CPU), comparator apparatus being common for an array of storage locations. The comparison results, determined in accordance with a CPU-specified criterion, are then communicated back to the processor.