Audio Amplifier Feedback for Secondary Resonance Damping
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Solution Overview
Problem
Conventional audio reproduction systems face challenges in efficiently managing secondary resonances in loudspeakers, leading to suboptimal frequency responses and potential overdriving of drone elements due to high Q resonances, which are difficult to control without reducing transducer efficiency or dissipating power.
Innovation Solution
The implementation of a negative current feedback mechanism to synthesize a positive output impedance for the audio power amplifier, which reduces the Q of secondary resonant systems without dissipating real power, allowing for high-efficiency transducers and improved frequency response control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional audio reproduction systems are used without synthesized positive impedance, then the system structure is simple, but secondary resonances cause high Q peaks leading to poor frequency response and potential drone overdriving
Solution Approach 1:
The patent applies negative current feedback to the audio power amplifier to synthesize a positive output impedance. The feedback signal is derived from sensing the current through the transducer and feeding it back to the amplifier input, creating an artificial positive impedance that dampens secondary resonances and controls drone excursion without requiring additional passive components.
Solution Approach 2:
The patent changes the effective output impedance parameter of the amplifier from its natural low value to a synthesized positive value through feedback. This parameter transformation allows the system to achieve desired damping of secondary resonances and control of drone elements while maintaining high transducer efficiency.
2Productivity
If high Q secondary resonant systems are used, then the system responds strongly at resonant frequencies, but this causes poor frequency response and potential overdriving of drone elements
Solution Approach 1:
The negative current feedback mechanism continuously monitors transducer current and adjusts the amplifier output to synthesize positive impedance, which provides automatic damping of high Q secondary resonances. This feedback action reduces drone excursion and flattens the frequency response while preserving the beneficial resonant response characteristics.
3Reliability
If positive impedance is used to damp secondary resonances, then frequency response improves, but real power is dissipated
Solution Approach 1:
The patent uses active feedback control to synthesize positive impedance, which dampens secondary resonances without dissipating real power like passive resistors would. The feedback mechanism recovers and redistributes energy, achieving damping through controlled impedance transformation rather than resistive loss.
Solution Approach 2:
The patent replaces the traditional mechanical/passive approach of using resistive damping with an electronic feedback-based synthesized impedance approach. This substitution eliminates the need for power-dissipating resistive elements while achieving the same damping effect through intelligent control.
4Productivity
If transducer efficiency is maximized, then system performance improves, but secondary resonances become more difficult to control
Solution Approach 1:
The negative current feedback system provides automatic control of secondary resonances that works effectively with high efficiency transducers. The feedback mechanism adapts to the transducer's electrical characteristics and provides the necessary damping without requiring complex passive networks or sacrificing transducer efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances system efficiency by decoupling transducer parameter selection from secondary resonance damping, achieving a desired frequency response while reducing drone excursion and maintaining high efficiency, even with varying system parameters over time.
Implementation Method 1
An electrical feedback signal representative of the transducer current is negatively fed back to the audio power amplifier to synthesize a positive output impedance
Implementation Method 2
a transducer electrically connected to the audio power amplifier
Implementation Method 3
an enclosure comprising a waveguide coupled to the transducer and a secondary resonant element coupled to the enclosure
Data Source
AI summary
An electrical apparatus to sense current through a load includes a first input terminal having a first input voltage relative to a reference, a second input terminal having a second input voltage relative to the reference, a first load terminal of the load having a first load voltage relative to the reference, a second load terminal of the load having a second load voltage relative to the reference, a first current sensing element connected between the first input terminal and the first load terminal and a second current sensing element connected between the second input terminal and the second load terminal. A first sense voltage is determined by a relationship between the first input voltage and the second load voltage and a second sense voltage is determined by a relationship between the second input voltage and the first load voltage.