Class D Audio Amplifier Reconfiguration Without Output Transformers
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Solution Overview
Problem
Existing audio amplifiers are limited by specific impedance modes, requiring different amplifiers or switchable amplifiers with multiple internal supply voltages and transformers for low-impedance and high-impedance operations, which is inefficient and costly, especially in complex sound reinforcement systems.
Innovation Solution
An audio amplifier with a switching mode output amplifier stage and a limiter device that adjusts the maximum output level, allowing flexible operation between low-impedance and high-impedance modes without the need for transformers or multiple internal supply voltages, using a class D amplifier with a bipolar power supply and a limiter device to control the output signal within a set maximum level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If low-impedance operation is used to directly drive loudspeakers, then the audio amplifier can provide high current output, but disproportionately large conductor cross-section is required for speaker cables
Solution Approach 1:
The patent applies parameter changes by transforming the output impedance parameter of the audio amplifier. Through the transformer, the amplifier switches between low-impedance mode (direct drive) and high-impedance mode (100V line output), changing the electrical parameters to match different application requirements and reduce conductor cross-section requirements
2Quantity of substance
If high-impedance operation with transformers is used to reduce conductor cross-section, then the device complexity increases due to additional transformers and voltage transformation components
Solution Approach 1:
The patent implements universality by designing the audio amplifier to perform multiple functions through a single device. The amplifier can operate in both low-impedance direct-drive mode and high-impedance 100V line mode, eliminating the need for separate amplifiers for different applications and reducing overall system complexity
Solution Approach 2:
The patent applies dynamics by making the amplifier's output characteristics adjustable and switchable. The amplifier can dynamically change its operating mode between low-impedance and high-impedance configurations, allowing flexible adaptation to different loudspeaker systems and cable requirements
3Adaptability or versatility
If switchable amplifiers with multiple internal supply voltages are used to support both low-impedance and high-impedance modes, then the adaptability improves, but the device complexity and cost increase
Solution Approach 1:
The patent achieves universality by designing a single audio amplifier that can function in both low-impedance and high-impedance modes. Through the transformer and switching mechanism, one amplifier replaces what would traditionally require multiple amplifiers with different supply voltages, reducing complexity while maintaining full adaptability
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
Enables flexible operation across a wide range of output powers and impedance levels, reducing the need for multiple amplifiers and transformers, and maintaining high efficiency and cost-effectiveness in both low-impedance and high-impedance applications.
Implementation Method 1
the output amplifier stage for amplifying an intermediate signal into the output signal being designed as an amplifier operating in switching mode
Data Source
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AI summary
Audio amplifiers are used in many known forms in music systems, for example for domestic use or for playing music in cinemas, discos etc., but also in public address systems, as are known, for example, in public buildings, schools, universities etc. for making announcements. The invention proposes an audio amplifier (1) for amplifying an input signal into an output signal using an output amplifier stage (6), wherein the output amplifier stage (6) is designed to amplify an intermediate signal into the output signal, and wherein the output amplifier stage (6) is in the form of an amplifier which operates in switching mode, and having a limiter device (4) which is designed, from a program and/or circuit point of view, to generate the intermediate signal on the basis of the input signal, wherein the level of the intermediate signal is always limited as a function of an adjustable maximum level in such a way that the output signal does not exceed the maximum level independently of the input signal.