Toroidal Transformer Output Stage for Low-Distortion Audio Amplifiers
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Solution Overview
Problem
Audio amplifiers face challenges in achieving low distortion and accurate signal reproduction, particularly in driving speakers effectively, due to limitations in existing transformer designs that can lead to magnetic saturation and inefficient signal processing.
Innovation Solution
The audio amplifier employs a push-pull configuration using two toroidal transformers with balanced current sources to prevent magnetic saturation, coupled with vacuum tube or solid-state amplifying elements driven by 180-degree out-of-phase control signals, operating in Class A mode to minimize distortion and enhance signal fidelity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional transformer designs are used in audio amplifiers, then power transfer to speakers is achieved, but magnetic saturation occurs and distortion increases
Solution Approach 1:
The patent divides the single transformer into two separate toroidal transformers, each handling one polarity of the push-pull signal. This segmentation prevents magnetic saturation in each transformer by ensuring they only process half the waveform, eliminating distortion while maintaining reliable signal transfer to the speaker.
Solution Approach 2:
The patent implements push-pull operation where two amplifying elements alternate processing positive and negative half-cycles of the input signal. This periodic action ensures each toroidal transformer operates within its linear range during its active half-cycle, preventing magnetic saturation and reducing distortion.
2Reliability
If push-pull configuration is used with toroidal transformers, then distortion is reduced and signal accuracy is improved, but device complexity increases
Solution Approach 1:
The patent combines two toroidal transformers with push-pull amplifying elements to create a unified output stage that delivers high-fidelity signal reproduction. The merged system processes the complete waveform through coordinated half-cycles, achieving superior signal fidelity while the modular toroidal design keeps individual components manageable.
3Object-generated harmful factors
If balanced current sources are used to prevent magnetic saturation, then distortion is minimized, but circuit complexity increases
Solution Approach 1:
The patent applies balanced current sources locally at each toroidal transformer primary winding to prevent magnetic saturation. Each current source is tailored to its specific transformer and amplifying element, ensuring optimal biasing and preventing saturation without requiring complex global control circuitry. This localized approach minimizes distortion while keeping the overall circuit manageable.
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 configuration significantly reduces distortion and improves signal accuracy, maintaining low output impedance and efficient power transfer to speakers, resulting in a more natural and subtle sound reproduction.
Implementation Method 1
a first toroidal transformer with first and second primary windings coupled together at center terminals to a common voltage source and coupled in push-pull configuration to the first and second amplifying elements, and with first and second secondary windings that are coupled in parallel across output terminals
Data Source
AI summary
An audio amplifier includes an output stage including a first toroidal transformer with a first pair of secondary windings that are coupled in parallel across an output terminal. The output stage further includes a second toroidal transformer with a second pair of secondary windings that are connected in a series combination that is coupled across the output terminal.