Introduction of Audio Power Amplifier

Last Update Time: 2018-12-03 13:50:59

Audio Power Amplifer is the amplifier which can produce the maximum power output to drive the sound of the load speaker under the given distortion rate. Audio power amplifier plays a pivotal role of "organization and coordination" in the whole audio system, and to some extent determines whether the whole system can provide good sound quality output. The main performance parameters of audio power amplifier include output power, frequency response, distortion, signal-to-noise ratio, output impedance, damping coefficient and so on. 

The main performance parameters of the audio power amplifier are briefly described below.


1. Output power

The unit of output power is W.There are different terms according to different measuring methods, such as rated output power and maximum output work.

Rate, music output power, peak music output power.

Output power. Music power: refers to the output distortion does not exceed the specified value, audio power amplifier on the music signal moment maximum

 Maximum music power. Peak low power; refers to the audio power amplifier under the condition of no distortion, when the audio power amplifier is tuned to the maximum, the audio power amplifier can output

Rated output power: the average output power, also known as maximum useful power, when the harmonic distortion is 10.

Usually, peak power > music power > rated output power, in general peak power is rated output power 5: 8 times.

2. Frequency response

The frequency response represents the frequency range of the audio power amplifier and the inhomogeneity within the frequency range. Whether the frequency response curve is straight or not is usually expressed in decibels db. Home Hi-Fi audio power amplifier as 20Hz 20kHz, as much as 1dB, the wider the better range. Some of the best audio power amplifiers have a frequency response of 0 1 100kHz.

3. Distortion

The ideal audio amplifier is to amplify the input signal and restore it faithfully without change. However, for a variety of reasons, the signal amplified by audio power amplifier often produces different degrees of distortion when compared with the input signal.

Distortion is distortion, expressed as a percentage, the smaller the value, the better. The total distortion of Hi-Fi audio power amplifier is between 0.03% and 0.05%. The distortion of audio power amplifier includes harmonic distortion, Intermodulation distortion, cross-distortion, clipping distortion, transient distortion, instantaneous distortionstate Intermodulation distortion, etc.


4. Signal-to-noise ratio

Signal-to-noise ratio (SNR) is the ratio of the signal level to the various noise levels of the output of the audio power amplifier.

The bigger the better. The signal-to-noise ratio of the general household Hi-Fi audio power amplifier is above 60dB.


5. Output impedance

The equivalent internal resistance presented to the loudspeaker is called the output impedance. The output impedance, or rated load impedance, usually has the equivalent of 82 4Q2 and 20. The smaller this value is, the stronger the load capacity of the power amplifier is. For a single channel, a power amplifier with a rated load of 22 can drive 4 speakers with impedance of 82 and have very little distortion.


6. Damping factor

The damping coefficient refers to the ratio of the load impedance of the power amplifier (the internal resistance of the high power tube plus the wiring resistance of the loudspeaker) to the actual impedance of the power amplifier, such as 892: 0.042 / 200: 1. Too general meeting feels loudspeaker sound is thin, too small can make the sound muddy sound layer drink bad, the sound image distribution is not good.