Hybrid Class D Audio Amplifier With Vacuum Tube Harmonic Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Class D amplifiers produce monotonous sound and suffer from reduced signal-to-noise ratio (SNR) and non-linearity due to switching noise and power noise during amplification, which affects the quality of the output audio signal.
Innovation Solution
An apparatus and method that incorporates a vacuum tube amplification unit to add harmonics to the amplified signal, combined with a pulse modulation and switching amplification unit using high-speed switching elements like GaN or GaAs transistors, to improve sound quality and reduce noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a Class D digital amplifier with switching amplification is used to achieve high amplification efficiency, then amplification efficiency is improved, but the output sound becomes hard and monotonous with reduced sound quality
Solution Approach 1:
The patent combines a Class D digital amplifier with a vacuum tube amplifier into a hybrid configuration. The digital amplifier handles power amplification for efficiency, while the vacuum tube amplifier processes the audio signal to add harmonic components and soften the sound, merging the advantages of both technologies to resolve the contradiction between efficiency and sound quality
Solution Approach 2:
The invention creates a composite amplification system that integrates digital switching amplification and vacuum tube amplification. This composite approach allows the system to achieve both high efficiency from the digital stage and warm, high-quality sound from the vacuum tube stage, overcoming the limitations of using either technology alone
2Use of energy by moving object
If a switching amplifier performs high-speed switching operation to achieve efficient amplification, then amplification efficiency is improved, but switching noise occurs causing reduction in signal to noise ratio (SNR)
Solution Approach 1:
The patent extracts the noise-generating switching operation from the audio signal path by implementing it only in the power amplification stage, while the vacuum tube amplifier handles the audio signal processing. This separation removes the source of switching noise from the critical audio path, eliminating the harmful effect while preserving the efficiency benefit
3Use of energy by moving object
If a switching amplifier is used to achieve high amplification efficiency, then amplification efficiency is improved, but non-linearity occurs in the output audio signal due to switching loss and delay
Solution Approach 1:
The vacuum tube amplifier serves as an intermediary between the digital audio input and the power amplification stage. It linearizes the signal by adding harmonic components that compensate for the non-linearity introduced by the switching amplifier, acting as a mediator that preserves signal fidelity while allowing efficient power amplification
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
The approach results in an audio signal with a mellow sound quality and increased SNR by minimizing switching noise and enhancing the linearity of the output audio signal.
Implementation Method 1
a vacuum tube amplification unit which inputs a vacuum tube signal generated by attenuating the amplified signal and adding harmonics of a vacuum tube to the amplified signal, to the modulation and amplification unit
Implementation Method 2
The vacuum tube attenuator may include a vacuum tube amplifier that has the predetermined negative gain value, and negatively amplifies the amplified signal by applying the predetermined negative gain value and outputs the negative amplified signal
Data Source
Figure 1~2
Figure 3~4a
Figure 4b~6a
AI summary
An apparatus for outputting an audio signal with improved sound quality is provided. The apparatus includes a modulation and amplification unit for pulse modulation and switching amplification of an input audio signal and generating an amplified signal which corresponds to the input audio signal; and a vacuum tube amplification unit for inputting a vacuum tube signal generated by attenuating the amplified signal and adding harmonics of a vacuum tube to the amplified signal, to the modulation and amplification unit to provide a mellow sound.