On Magnetic Distortion in Audio Amplifiers
It is usual in audio amplifiers for magnetic materials (used in the transformers, chassis, casing, etc.) to be situated near the signal current circuitry because of circuitry design and mechanism design considerations. This paper is intended to prove that distortion (odd harmonic distortion), due to the effects (L-E curve) of magnetic materials located near the signal current circuit, is generated inside the amplifier and that this distortion, caused by these magnetic materials, depends greatly on the current flowing in the circuitry. We undertook theoretical analysis to find the non-linear impedance curve, which is the cause of the distortion (here, the distortion originating in the B-H curve is treated at the voltage-versus-current ratio), from the harmonic level of the distortion components. Consequently, this report shows that in order to suppress this distortion in the circuit design of an audio amplifier where high current levels are recorded, it is necessary to consider not only circuit design techniques but also the materials used near the circuitry. It also shows that excellent results were obtained by making this policy applicable to the design of actual amplifiers.
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