Introduction of audio performance index of power amplifier

Introduction of audio performance index of power amplifier

What are the performance indicators of power amplifier audio? People who like music can't live without the stereo at home. They have some knowledge about the parameters and selection of stereo, but may not have a comprehensive understanding. The following is an introduction to the audio performance index of the amplifier.

The main performance indexes of 1 power amplifier include output power, frequency response, distortion, signal-to-noise ratio, output impedance and damping coefficient.

Music power

Music power: refers to the instantaneous maximum output power of the power amplifier to the music signal under the condition that the output distortion does not exceed the specified value.

Output rate

Output power: W. Because different manufacturers have different measurement methods, there are some different names. Such as rated output power, maximum output power, music output power and peak music output power.

peak power

Peak power: refers to the maximum music power that can be output by the amplifier when the volume of the amplifier is adjusted to the maximum without distortion.

power amplifier

As far as music power is concerned, the music power is greater than the rated power. Generally speaking, the peak power is 5-8 times the rated power.

Output rate

Rated output power: the average output power with harmonic distortion of 10%. Also known as the maximum useful power. Generally speaking, the peak power is high.

Amplitude-frequency response of recording and playback

Frequency response: indicates the frequency range of the power amplifier and the inhomogeneity within the frequency range. Whether the frequency response curve is flat or not is generally expressed in decibel db. The frequency response of household high fidelity power amplifier is generally 20 Hz-20 kHz1db. The wider the scope, the better. The frequency response of some top power amplifiers has reached 0- 100 kHz.

Signal Noise Ratio (SNR)

Signal-to-noise ratio: refers to the ratio of signal level to various noise levels output by power amplifier, expressed in db, and the larger the value, the better. The signal-to-noise ratio of general household high-fidelity power amplifier is above 60db.

degree of distortion

Distortion: An ideal power amplifier should amplify the input signal and faithfully restore it without change. However, due to various reasons, the signal amplified by the power amplifier often produces different degrees of distortion compared with the input signal, which is distortion. Expressed as a percentage, the smaller the number, the better. The total distortion of high fidelity power amplifier is between 0.03% and 0.05%. The distortion of power amplifier includes harmonic distortion, intermodulation distortion, cross distortion, clipping distortion, transient distortion, transient intermodulation distortion and so on.

Output impedance

Output impedance: The equivalent internal resistance presented to the speaker is called output impedance.

A good performance index of the power amplifier does not necessarily prove a good timbre, which is something that friends who are in contact for the first time must realize. This is also the pursuit of many enthusiasts.

Introduction of performance index and expansibility of amplifier audio 2 1

This refers to whether the speaker supports multi-channel simultaneous input, whether there is an output interface for passive surround speakers and whether there is a USB input function. The number of surround speakers that the subwoofer can connect is also one of the criteria to measure the expansion performance.

2. Sound technology

Nowadays, there are several commonly used hardware 3D sound effects technologies, such as SRS, APX, Spatializer 3D, Q-SOUND, Virtaul Dolby and Ymersion. Although the implementation methods are different, they can all make people feel obvious 3D sound field effects, among which the first three are more common. They all apply the theory of extended stereo, that is, adding processing to the sound signal through the circuit, so that the listener feels that the audio-visual orientation extends beyond the two speakers, thus expanding the audio-visual image, giving people a sense of space and three-dimensionality, and producing a wider stereo effect. In addition, there are two sound enhancement technologies: active electromechanical servo technology (essentially using Helmholtz vibration principle), BBE high-definition plateau sound playback system technology and "phase fax" technology, which also have certain effects on improving sound quality. For multimedia speakers, SRS and BBE are relatively easy to implement, and the effect is very good, which can effectively improve the performance of speakers.

3. Tone

Refers to a signal with a specific and usually stable pitch, which is the degree to which the sound sounds high or low. It depends mainly on frequency, but also on sound intensity. The human ear responds to high-pitched high-frequency sounds and low-pitched low-frequency sounds. The change of pitch with frequency (Hz) is basically logarithmic. Different musical instruments play notes at the same frequency. Although their timbres are different, their tones are the same, that is, the fundamental frequency of the playing sound is the same.

4, timbre

The feeling of sound quality is also the characteristic quality that distinguishes one sound from another. When different instruments make the same tone, their colors may be different. This is because their fundamental frequencies are the same, but their harmonic components are quite different. Therefore, the timbre depends not only on the fundamental frequency, but also on the harmonics of the fundamental frequency, which makes each instrument and everyone have different timbre.

5. Channel separation

Refers to the ability and degree of non-interference between two channels, that is, isolation, which is usually expressed by the difference between the signal level in one channel and the level leaked into the other channel. If the stereoscopic separation is poor, the stereoscopic impression will be weakened. The minimum index of stereo separation specified by IEC is 40dB or higher at lKHz, and it is best to reach 60dB in practice. The stereo separation of FM stereo radio specified by European Broadcasting Union is 25dB, which can actually exceed 40dB. Stereo channel balance refers to the gain difference between the left and right channels, which is generally expressed by the maximum difference between the output levels of the left and right channels. If the imbalance is too large, the stereo sound image position will deviate, and the index should be less than 1dB.

6. Damping coefficient

Refers to the ratio of rated load (speaker) impedance of amplifier to actual impedance of power amplifier. A large damping coefficient means that the output resistance of the power amplifier is small, and the damping coefficient is the amplifier's ability to control the speaker cone motion after the signal disappears. An amplifier with high damping coefficient is more like a short circuit of a speaker, which can reduce its vibration when the signal is terminated. The output impedance of the power amplifier will directly affect the low-frequency Q value of the speaker system, thus affecting the low-frequency characteristics of the system. The q value of loudspeaker system should not be too high, and it is generally better in the range of 0.5 ~ l. The output impedance of power amplifier is the factor that makes the low frequency Q value rise, so it is generally expected that the output impedance of power amplifier is small and the damping coefficient is large. The damping coefficient is generally between tens and hundreds, and the damping coefficient of high-quality professional power amplifier can be as high as 200 or more. www.gsnssm.com

7, equal loudness control

Its function is to raise high-frequency and low-frequency sounds at a low volume. Because human ears have poor auditory sensitivity to high-frequency sounds, especially low-frequency sounds, it is required to compensate high-frequency and low-frequency sounds at low volume, that is, to improve high-frequency sounds to a certain extent while greatly improving low-frequency sounds. In other words, when the volume decreases, the decrease of the low-frequency part of the signal is smaller than that of the high-frequency part. Equal loudness control meets this requirement, generally 8dB or 10dB.

8. Three-dimensional sound stage processing and surround sound.

Why do ordinary two speakers let us hear sounds that don't exist, as if they were coming from behind? As we all know, the three-dimensional movie is an illusion produced by the eyes, and the three-dimensional sound stage can not be produced without the illusion of the ears. Various hardware 3D sound effects technologies (such as SRS, virtual Dolby and software 3D technologies (such as EAX and A3D) are new technologies introduced after fully studying the principle of human ear receiving sound, aiming at reducing costs. In essence, the effect of completing the three-dimensional sound stage through multiple speakers is much better than the virtual sound field created by two speakers. Therefore, surround sound should be based on multi-speaker configuration, which has a strong sense of positioning and space.