Dynamic contoured-sound/subwoofer-synthesis audio system

A dynamic contoured-sound/subwoofer-synthesis system comprising:

• an input terminal designed to receive an audio signal and an output terminal designed to supply an output signal to an external load;
• an adjustable high pass filter coupled to the input terminal and including an isolation resistor, a multi-step digital potentiometer, and a divider resistor connected to the input terminal to form a voltage divider, the adjustable high pass filter further including a filter input capacitor coupled in circuit with the multi-step digital potentiometer and the divider resistor to form a high pass filter, the high pass filter being designed to provide a variety of frequency response shapes in response to adjustments of the adjustable component;
• a primary amplifier coupled to receive a frequency response shape of the variety of frequency response shapes from the adjustable high pass filter, the primary amplifier including a main operational amplifier having an inverting input, a non-inverting input, and a signal output, the inverting input being coupled to the adjustable high pass filter through a series connected input capacitor and input resistor to receive the frequency response shape of the variety of frequency response shapes, the input capacitor and input resistor forming a band pass filter connected to set a bandwidth of frequencies passed from the adjustable high pass filter to the main operational amplifier;
• and
• the primary amplifier further including a first feedback resistor coupled between the signal output and the inverting input of the main operational amplifier, and a second feedback resistor and a feedback capacitor, the input resistor, the first feedback resistor, the second feedback resistor, and the feedback capacitor being connected to form a high pass filter connected to set the voltage gain of the main operational amplifier.

A dynamic contoured-sound/subwoofer-synthesis system comprising:

• an input terminal designed to receive an audio signal and an output terminal designed to supply an output signal to an external load;
• an adjustable high pass filter coupled to the input terminal and including an adjustable component, the high pass filter being designed to provide a variety of frequency response shapes in response to adjustments of the adjustable component;
• a primary amplifier coupled to receive a frequency response shape of the variety of frequency response shapes from the adjustable high pass filter, the primary amplifier including a main operational amplifier having an inverting input, a non-inverting input, and a signal output, the inverting input being coupled to the adjustable high pass filter through a series connected input capacitor and input resistor to receive the frequency response shape of the variety of frequency response shapes, the primary amplifier further including a first feedback resistor coupled between the signal output and the inverting input of the main operational amplifier, the primary amplifier providing low frequency signal gain and shaping of the received frequency response shape to the output terminal;
• and
• a high frequency signal shaping circuit including a feedback operational amplifier having an inverting input, a non-inverting input, and a signal output, the high frequency signal shaping circuit including a second feedback resistor and a feedback capacitor, the signal output of the feedback operational amplifier being coupled to the inverting input of the main operational amplifier through the second feedback resistor and the feedback capacitor, the inverting input of the feedback operational amplifier being coupled to the signal output of the main operational amplifier through a first differential gain resistor, and the non-inverting input of the feedback operational amplifier being coupled to the signal output of the main operational amplifier through a second differential gain resistor with a resistance value different than a resistance value of the first differential gain resistor.

A method of synthesizing subwoofer sound in a sound producing device comprising the steps of:

• providing an adjustable high pass filter having a plurality of step settings and constructed with each setting having a different frequency of emphasis and the frequency of emphasis for each setting occurring at a lower frequency than a prior setting, and each setting having a different magnitude of gain change, for each setting the magnitude of gain change is greater than a prior setting;
• applying audio signals to the adjustable high pass filter for controlling the amount of subwoofer synthesis of the audio signals, each step setting providing a different frequency response shape, and selecting a step setting of the high pass filter to provide a preferred frequency response shape of the different frequency response shapes;
• and
• receiving the preferred frequency response shape of the different frequency response shapes from the adjustable high pass filter and amplifying the preferred frequency response shape to provide low frequency signal gain and shaping of the preferred frequency response shape.

A method of contouring sound in a sound producing device comprising the steps of:

• providing a primary amplifier;
• providing an adjustable simulated inductor having a plurality of step settings and constructed with each step setting of the plurality of step settings having a different frequency of emphasis and the frequency of emphasis for each step setting occurring at a higher frequency than a prior step setting and each step setting having a different magnitude of gain change, for each step setting the magnitude of gain change is greater than a prior step setting;
• applying audio signals from the output of the primary amplifier to the adjustable simulated inductor for controlling the amount of high frequency contoured sound of the audio signals, each step setting of the plurality of step settings providing a different frequency response shape;
• and
• selecting a step setting of the simulated inductor to provide a preferred frequency response shape of the different frequency response shapes.