Circuit arrangement capable of continuously varying tone colors for electrical musical instruments

Claim 2

An electrical musical instrument comprising: means for generating tone signals having a relatively broad frequency band; loud-speaker means for converting said tone signals to audible sounds; circuit means connected between said tone signal generating means and loud-speaker means to pick up only tone signals having a relatively narrow frequency band from among those having said relatively broad frequency band and transmit the former tone signals from said tone signal generating means to said loud-speaker means, said circuit means including a variable gain amplifier whose gain varies in accordance with the magnitude of an A. C. input impedance, and a reactive impedance element connected between the output and input of said amplifier to provide an apparent reactive impedance to said amplifier according to the magnitude of its gain; a foot operated pedal movable in a horizontal plane; means in the gain circuit of said amplifier and connected to said foot operated pedal for continuously controlling the gain of said amplifier in response to horizontal movement of said pedal thereby successively to shift the relatively narrow frequency band of tone signals transmitted from said tone generating means to said loud speaker means over said relatively broad frequency range of tone signals; said circuit means further including first amplifier means for amplifying tone signals; second amplifier means connected to the output of said first amplifier means; third amplifier means connected to the output of said first amplifier means; a variable A.C. impedance circuit connected to the inputs f said second and third amplifier means and controlled by said gain varying means to cause either of the second and third amplifier means to have a larger gain than theother; a first reactive impedance means connected between the output of said second amplifier means and the input of sai first amplifier means to provide said first and second amplifier Means with a first apparent reactive input impedance whose magnitude varies with the gain of said second amplifier means; and a second reactive impedance means connected between the output of said third amplifier means and the input of said first amplifier means to provide said first and third amplifier means with a second apparent reactive input impedance whose magnitude varies with the gain of said third amplifier means and constitute a resonance circuit with said first apparent reactive input impedance.

Claim 3

An electrical musical instrument according to claim 14 wherein said A.C. impedance circuit includes a potentiometer provided with a slidable arm and connected between the input terminals of said second and third amplifier means and a capacitor connected between said slidable arm and an A.C. grounded point.

Claim 4

An electrical musical insturment comprising: means for generating tone signals having a relatively broad frequency band; loud-speaker means for converting said tone signals to audible sounds; circuit means connected between said tone signal generating means and loud-speaker means to pick up only tone signals having a relatively narrow frequency band from among those having said relatively broad frequency band and transmit the former tone signals from said tone signal generating means to said loud-speaker means, said circuit means including a variable gain amplifier whose gain varies in accordance with the magnitude of an A.C. input impedance, and a reactive impedance element connected between the output and input of said amplifier to provide an apparent reactive impedance to said amplifier according to the magnitude of its gain; a foot operated pedal movable in a horizontal plane; means in the gain circuit of said amplifier and connected to said foot operated pedal for continuously controlling the gain of said amplifier in response to orizontal movement of said pedal thereby successively to shift the relatively narrow frequency band of tone signals transmitted from said tone generating means to said loud-speaker means over said relatively broad frequency range of tone signals; said circuit means further including; first amplifier means for amplifying tone signals; second amplifier means connected to the output of said first amplifier means; a variable A.C. impedance circuit connected to the input of said second amplfier means to be controlled by said gain varying means so as to vary the gain of said second amplifier means; means for drawing out output from said second amplifier means whose phase is reversed from that of output of said first amplifier means; third amplifier means connected to the output of said first amplifier means and said means for drawing out output whose phase is reversed from that of output of said first amplifier means to have the gain of said third amplifier means itself varied apparently in reverse relationship from said second amplifier means; a first reactive impedance means connected between the output of said second amplifier means and the input of said first amplifier means to provide said first and second amplifier means with the first apparent reactive input impedance whose magnitude varies with the gain of said second amplifier means; and a second reactive impedance means connected between the output of said third amplifier means and the input of said first amplifier means so as to supply said first and third amplifier means with the second apparent reactive input impedance whose magnitude varies with the gain of said third amplifier means and constitute a resonance circuit jointly with the first reactive impedance.

Claim 5

An electrical musical insturment comprising: means for generating tone signals having a relatively broad frequency band; loud-speaker means for converting said tone signals to audible sounds; circuit means connected between said tone signal generating means and loud-speaker means to pick up only tone signals having a relatively narrow frequency band from among those having said relatively broad frequency band and transmit the former tone signals from said tone signal generating means to said loud-speaker means, said circuit means including a variable gain amplifier whose gain varies in accordance with the magnitude of an A.C. input impedance, and a reactive impedance element connected between the output and input of said amplifier to provide an apparent reactive impedance to said amplifier according to the magnitude of its gain; a foot operated pedal movable in a horizontal plane; means in the gain circuit of said amplifier and connected to said foot operated pedal for continuously controlling the gain of said amplifier in response to orizontal movement of said pedal thereby successively to shift the relatively narrow frequency band of tone signals transmitted from said tone generating means to said loud-speaker means over said relatively broad frequency range of tone signals; said circuit means further including; first amplifier means for amplifying tone signals; second amplifier means connected to the output of said first amplifier means; a variable A.C. impedance circuit connected to the input of said second amplfier means to be controlled by said gain varying means so as to vary the gain of said second amplifier means; means for drawing out output from said second amplifier means whose phase is reversed from that of output of said first amplifier means; third amplifier means connected to the output of said first amplifier means and said means for drawing out output whose phase is reversed from that of output of said first amplifier means to have the gain of said third amplifier means itself varied apparently in reverse relationship from said second amplifier means; a first reactive impedance means connected between the output of said second amplifier means and the input of said first amplifier means to provide said first and second amplifier means with the first apparent reactive input impedance whose magnitude varies with the gain of said second amplifier means; and a second reactive impedance means connected between the output of said third amplifier means and the input of said first amplifier means so as to supply said first and third amplifier means with the second apparent reactive input impedance whose magnitude varies with the gain of said third amplifier means and constitute a resonance circuit jointly with the first reactive impedance.

Claim 6

An electrical musical instrument according to claim 3 wherein said A.C. impedance circuit includes a series connection of a capacitor and a variable resistor, said capacitor being connected between the input terminal of said second amplifier means and an A.C. ground point, and said variable resistor being a photoconductive element whose resistance varies with the inteNsity of light projected thereon.