Audio fidelity frequency equalizer system

Claim 2

An audio fidelity frequency equalizer system comprising input means, an operational amplifier operatively connected to said input means, a resistive feedback path connected across an output of and an input to said operational amplifier, a plurality of discrete octave band potentiometer elements connected between said feedback circuit and said first named input to said operational amplifier and where said frequency controlling potentiometer elements are connected in parallel ralationship with respect to each other and with respect to the output of and the first named input to said operational amplifier, an individual resonant octave band control circuit connected with respect to each said octave band control potentiometer element, and each said resonant control circuit including an inductive-capacitive circuit therein comprised of an electronically active simulated inductor and a capacitor connected thereto, each said octave band control circuit operating in conjunction with the associated potentiometer element to adjust the frequency of a particular octave band as a function of the inductance generated by the electronically active simulated inductor.

Claim 3

The audio fidelity frequency equalizer system of claim 1 further characterized in that said inductive-capacitive circuit includes a second operational amplifier and a capacitor connected in feedback relationship thereacross.

Claim 4

The audio fidelity frequency equalizer system of claim 1 further characterized in that the inductive-capacitive circuit includes an NPN transistor with a capacitor connected in feedback relationship thereacross.

Claim 5

The audio fidelity frequency equalizer system of claim 1 further characterized in that an impedance amplifier is connected between the input means and the operational amplifier thereof and which includes a unity gain feedback path thereacross.

Claim 6

The audio fidelity frequency equalizer system of claim 1 further characterized in that a capacitive circuit isolation element is connected to the output of the operational amplifier.

Claim 7

The audio fidelity frequency equalizer system of claim 1 further characterized in that each octave band of each frequency channel has a resonant frequency approaching approximately zero frequency at a selected input impedance with respect to the octave band value setting.

Claim 10

The method of claim 7 further characterized in that said method comprises determining the resonant frequency by means of a capacitive-inductive circuit comprised of said amplifier type element and capacitor and thereby controlling the gain of the operational amplifier.

Claim 11

The method of claim 7 further characterized in that DC isolation is connected across the output of the equalizer system in order to eliminate any DC output transients.

Claim 12

An audio fidelity frequency equalizer system comprising input means, an operational amplifier operatively connected to said input means, a resistive feedback path connected across an output of and an input to said operational amplifier, a plurality of discrete octave band potentiometer elements connected between said feedback circuit and said first named input to said operational amplifier and where said frequency controlling potentiometer elements are connected in parallel relationship with respect to each other and with respect to the output of and the first named input to said operational amplifier, an individual resonant octave band control circuit connected with respect to each said octave band control potentiometer element, each said resonant control circuit comprising an electronically active amplifier type element operating as an electronically active simulated inductor, capacitive means connected in series relationship to said amplifier type element, each said octave band control circuit operating in conjunction with the associated potentiometer element to adjust the frequency of a particular octave band as a function of the inductance generated by the electronically active amplifier type element, and establishing a zero impedance for each selected octave band frequency in a channel thereby achieving a resonant point for such frequency.

Claim 13

An audio fidelity frequency equalizer system comprising input means, an operational amplifier operatively connected to said input means, a resistive feedback path connected across an output of and an input to said operational amplifier, a plurality of discrete octave band potentiometer elements connected between said feedback circuit and said first named input to said operational amplifier and where said frequency controlling potentiometer elements are connected in parallel relationship with respect to each other and with respect to the output of and the first named input to said operational amplifier, an individual resonant octave band control circuit connected with respect to each said octave band control potentiometer element, each said resonant control circuit comprising an electronically active amplifier type element operating as an electronically active simulated inductor, capacitive means connected in series relationship to said amplifier type element, each said octave band control circuit operating in conjunction with the associated potentiometer element to adjust the frequency of a particular octave band as a function of the inductance generated by the electronically active amplifier type element, and establishing a zero impedance for each selected octave band frequency in a channel thereby achieving a resonant point for such frequency.

Claim 14

The audio fidelity frequency equalizer system of claim 10 further characterized in that the capacitive means is a capacitor connected across said amplifier type element.

Claim 15

The audio fidelity frequency equalizer system of claim 11 further characterized in that a resistor is connected to the output of said amplifier type element, said capacitor is connected to said resistor and a terminal of the amplifier type element.

Claim 16

The audio fidelity frequency equalizer system of claim 10 further characterized in the said electronically active inductor comprises a second operational amplifier and a capacitor connected in feedback relationship thereacross.

Claim 17

The audio fidelity frequency equalizer system of claim 10 further characterized in that the electronically active inducter comprises an NPN transistor with a capacitor connected in feedback relationship thereacross.

Claim 18

An audio fidelity frequency equalizer system comprising input means, an operational amplifier terminal having a pair of inputs and an output terminal, one of said input terminals being operatively connected to said input means, a resistive feedback path connected across an output terminal of and the other of said input terminals to said operational amplifier, a plurality of discrete octave band potentiometer elements connected between said feedback circuit and said first named input to said operational amplifier and where said frequency controlling potentiometer elements are connected in parallel relationship with respect to each other and with respect to the output of and the first named input to said operational amplifier, an individual resonant octave band control circuit connected with respect to each said octave band control potentiometer element, and each said resonant control circuit including an inductive-capacitive circuit therein comprised of a series connected electronically simulated inductor and capacitor.

Claim 19

An audio fidelity frequency equalizer system comprising input means, an operational amplifier terminal having a pair of inputs and an output terminal, one of said input terminals being operatively connected to said input means, a resistive feedback path connected across an output terminal of and the other of said input terminals to said operational amplifier, a plurality of discrete octave band potentiometer elements connected between said feedback circuit and said first named input to said operational amplifier and where said frequency controlling potentiometer elements are connected in parallel relationship with respect to each other and with respect to the output of and the first named input to said operational amplifier, an individual resonant octave band control circuit connected with respect to each said octave band control potentiometer element, and each said resonant control circuit including an inductive-capacitive circuit therein comprised of a series connected electronically simulated inductor and capacitor.

Claim 20

The audio fidelity frequency equalizer system of claim 15 further characterized in that said inductive-capacitive circuit includes a second operational amplifier and a capacitor connected in feedback relationship thereacross.

Claim 21

The audio fidelity frequency equalizer system of claim 15 further characterized in that the inductive-capacitive circuit includes an NPN transistor with a capacitor connected in feedback relationship thereacross.