Audio Amplifier Harmonic Balancing for Subjective Sound Quality
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Solution Overview
Problem
Current audio amplifiers rely on Total Harmonic Distortion (THD) specifications, which are unreliable in determining subjective sound quality as they do not account for the nuances of the structural relationship between harmonic distortion orders, leading to inconsistent and potentially degraded sound quality.
Innovation Solution
The Harmonic Balancing Amplifier (HBA) adjusts the spectrum of fundamental harmonic distortion orders by varying input impedance loadings, allowing for customizable harmonic distortion profiles that can balance even and odd orders, enabling a more reliable and subjective sound quality adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If techniques are employed to lower the THD of an amplifier, then the THD specification is reduced, but the subjective sound quality may degrade
Solution Approach 1:
The patent changes the approach from minimizing all harmonic distortion to selectively balancing even and odd order harmonics. By adjusting the amplifier circuit to achieve a specific harmonic distribution pattern rather than simply reducing total THD, the system maintains or improves subjective sound quality while achieving meaningful distortion control.
Solution Approach 2:
Instead of treating all harmonic distortion equally and attempting to minimize the total THD, the patent inverts the approach by recognizing that certain harmonics (even orders) are more desirable than others (odd orders). The system actively promotes even order harmonics while suppressing odd order harmonics, reversing the conventional wisdom that all distortion should be minimized.
2Measurement precision
If an amplifier circuit design reduces the second order harmonic distortion, then the THD is reduced, but the odd orders of harmonic distortion become relatively greater
Solution Approach 1:
The patent converts the typically harmful odd order harmonics into a controlled aspect of the distortion spectrum by selectively suppressing them while promoting even order harmonics. What was previously considered purely harmful (odd order distortion) is now managed as part of a balanced harmonic spectrum that contributes to desirable sound quality.
Solution Approach 2:
The patent applies different treatment to different harmonic orders rather than treating all distortion equally. Even order harmonics are promoted or maintained while odd order harmonics are suppressed, creating a non-uniform distortion spectrum with localized quality characteristics that enhance subjective sound perception.
3Reliability
If vacuum tube amplifiers are used to achieve predominantly even order THD spectrum, then the sound quality is perceived as warm and smooth, but the technology has lower efficiency compared to solid-state amplifiers
Solution Approach 1:
The patent merges the desirable even order harmonic characteristics of vacuum tube amplifiers with the efficiency advantages of solid-state technology. By using solid-state circuitry configured to produce even order dominant harmonic distortion, the system achieves the warm and smooth sound quality associated with tube amplifiers while maintaining the energy efficiency and reliability of solid-state construction.
Data Source
AI summary
An amplifier stage uses a loaded transistor amplifier circuit including a load that causes greater second order harmonic distortion energy than third order harmonic distortion energy to be produced in said loaded transistor amplifier circuit for amplifying a source audio signal to produce an audio output signal. The spectrum of the fundamental orders of harmonic distortion is adjusted to improve perceived sound quality or listening enjoyment.