Power Amplifier Sound Distortion119

When the amplified signal of a power amplifier is different from the input signal, the sound emitted by the speaker will produce varying degrees of distortion, which will seriously affect the sound quality of the amplified sound. The most prominent performance of sound distortion is the loss of high-frequency components, which makes the treble sound dull, and the heavy distortion will also produce intermodulation products, which will add new frequency components to the original sound, making the sound chaotic and harsh.

There are three main types of sound distortion in power amplifiers, namely harmonic distortion, intermodulation distortion and transient intermodulation distortion. Harmonic distortion refers to the distortion caused by nonlinear amplification of the input signal, which is a single sine wave. The distorted signal contains harmonic components of the fundamental wave, which can be divided into even harmonic distortion and odd harmonic distortion. The former only contains even harmonic components, while the latter mainly contains odd harmonic components.

Intermodulation distortion is an additional distortion component generated by the amplifier when the signal contains two or more frequencies. For example, when the amplifier inputs two sine waves with different frequencies, the output signal will contain additional frequency components, such as the sum and difference frequencies of the two original frequencies and their multiples. If the amplifier has large intermodulation distortion, it will seriously degrade the sound quality during playback of music or film soundtracks.

Transient intermodulation distortion is a more complex distortion phenomenon. When an amplifier is driven by a square wave or pulse signal, the output signal will contain transient intermodulation distortion components. This is because the amplifier cannot respond quickly enough to the sudden changes in the input signal, resulting in the generation of additional distortion components. Transient intermodulation distortion can make the sound muddy and lacking in detail.

The main causes of sound distortion in power amplifiers are as follows:
Non-linearity of the power amplifier circuit: The transfer characteristic curve of the power amplifier is not a straight line, but a curve. When the input signal is amplified, the output signal will be distorted due to the non-linearity of the circuit.
Clipping: When the input signal exceeds the maximum output power of the power amplifier, the output signal will be clipped, resulting in sound distortion.
Crossover distortion: When the output transistors of the power amplifier are turned on and off, there will be a short period of time when both transistors are in the on state. This will cause a short circuit of the power supply and produce crossover distortion.

There are several ways to reduce sound distortion in power amplifiers:
Use a feedback circuit to improve the linearity of the power amplifier circuit.
Increase the output power of the power amplifier to avoid clipping.
Use a complementary symmetry circuit to reduce crossover distortion.

By reducing sound distortion, the power amplifier can reproduce the original sound more accurately, improve the sound quality, and bring a better listening experience to users.

2024-11-06

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