What is AV amplifier and the difference between AV amplifier and Hi-Fi amplifier
AV amplifier , that is, the amplifier used in the audio-visual system, used in the audio-visual system of the home theater, and the power amplifier is complete. AV power amplifiers generally have 4~7 channel power outputs such as front, center and surround, and some have Dolby Pro Logic surround decoder or AC-3 decoder, DSP digital sound field processing, FM/AM digital tuning radio It also has a variety of audio input and output interfaces, and some power amplifiers also have SVIDEO (high-definition) video four-pin interfaces. Various functions can be controlled by the remote control, which is very convenient to use.
First, the principle of AV power amplifier
AV power amplifier, as the name suggests, is used to cooperate with the video source, produce the effect of audio-visual integration, to create Amplifiers that are primarily designed for home theater use. It controls the delay time between each channel during playback through its internal delay and reverberation processing circuits, and simulates the sound field in various listening environments by adjusting the length of the delay time, such as halls, churches, stadiums, studio etc. AV amplifiers emphasize channel isolation, delay time range, various sound field modes and other indicators. The channels of AV power amplifiers are as few as four channels, and as many as nine channels. At present, the AV power amplifiers on the market are combined with the needs of home playback, and most of them are five channels or seven channels.
The AV system is mainly composed of large-screen color TV, DVD player or high-fidelity video recorder, AV multi-channel surround amplifier, a center speaker, a pair of main speakers, and a pair of surround speakers. The AV system focuses on the performance of large dynamic sound effects to enhance the atmosphere and create a thrilling scene with the sound field positioning of the picture. People can enjoy the unique audio-visual effects in movie theaters at home.
AV multi-channel surround sound system mainly includes Dolby Logic surround sound system, THX system, and Yamaha’s cinema CINEMA DSP system. Each of these three systems has its own merits. Dolby Logic surround sound is recorded in multi-channel, generally speaking, four-channel. When recording, multiple pickups are used and placed in all directions of the performer at different distances to pick up the sound signal. After AD into digital, these digital codes are encoded according to certain rules, compiled into two-channel digital, and finally recorded on a two-channel video disc. When people want to enjoy the video disc, the Dolby Logic decoding system inversely converts the two-channel digital into four-channel or five-channel digital, and then through DA conversion, through the AV multi-channel amplifier, to several pairs of different Positioned speakers to achieve surround sound, and strive to reproduce the style of live recording. Yamaha’s CINEMADSP was developed from Dolby Logic. It is fully compatible with the Dolby Logic decoding surround sound system and has its own unique characteristics. The digital sound field processing is a unique technology of Yamaha CIN? EMADSP. It uses DSP (digital signal processing chip) and CPU to store the parameters of sound field propagation in specific occasions such as fields, churches, concert halls, canyons, etc., and directly adds the parameters to the surround sound after Dolby Logic decoding, so that It makes up for the lack of Dolby surround sound.
Second, AV power amplifier technical indicators
AV power amplifier is an important part of home theater, its performance is mainly composed of The following indicators are determined:
1. Signal-to-noise ratio
The signal-to-noise ratio refers to the decibel difference between the audio signal level and the noise level. The higher the signal-to-noise ratio value, the smaller the relative noise of the amplifier and the better the sound quality.
2. Output power
Output power refers to the energy obtained from the speakers connected to the power amplifier. The RMS power that can be continuously output without distortion) is an effective indicator for evaluating the performance of the power amplifier.
3. Frequency response
Short for frequency response, it measures the ability of a piece of equipment to reproduce signals in high, medium and low frequency bands evenly.
4. Distortion
The output of the device cannot completely reproduce its input, and the distortion of the waveform or the increase or decrease of the signal component is called distortion. The less distortion, the better the sound quality.
5. Dynamic range
The level difference between the strongest part and the weakest part of the signal. The ability of the device to respond to strong and weak signals.
6. Damping coefficient
The damping coefficient refers to the ratio of the load impedance to the output impedance of the amplifier, and is a measure of the damping effect of the internal resistance of the power amplifier on the speaker. a performance indicator.
7. Output impedance
The output impedance of the power amplifier refers to the equivalent internal resistance of the output terminal to the speaker, which should be the same as the speaker’s output impedance. The rated input impedance is the same.
8. Separation
Separation refers to the ability of the surround sound decoder in the AV power amplifier to restore the audio encoded signal to each channel signal. Amplifiers with poor separation will appear inaccurate sound image positioning, sound field is not full, poor sound image coherence and so on.
Three, the difference with Hi-Fi amplifier
Hi-Fi is the abbreviation of English High-Fidelity, literally translated as high fidelity, it requires audio During the playback process, the equipment amplifies and processes the various indicators of the sound signal without distortion, so as to restore the original appearance of the sound source. Audio and sound, V (video) means audio and image, so AV amplifier is an audio-visual amplifier that combines audio and video signal processing, emphasizing the atmosphere of the sound field, and is specially used in home theaters. Due to their different emphasis, these two power amplifiers have different technical indicators, sound field atmosphere, number of channels, circuit design, etc.:
1 , different technical indicators
The technical indicators of high-fidelity Hi-Fi power amplifiers mainly include output power, harmonic distortion, signal-to-noise ratio, frequency range, rated impedance and damping coefficient, etc. Harmonic distortion and signal-to-noise ratio, etc. Although AV power amplifiers also have these technical indicators, they emphasize channel isolation, delay time range, and various sound field modes (DSP system, home THX system, Dolby AC-3 system) and other indicators parameters, in addition, the AV power amplifier also has more indicators related to the video part.
2. The sound field atmosphere is different
Hi-Fi amplifiers are designed for high fidelity in the way of sound reproduction, and pay attention to the original amplifying signal source The signal sent is mainly used to appreciate music, vocals, etc., and pursue the real effect of the sound. The main design purpose of the AV amplifier is to create a sound field, emphasizing the sense of orientation of the sound, and simulating the atmosphere of the listening environment, such as movie theaters, halls, churches, stadiums, studios, and so on.
3. The number of playback channels is different
Hi-Fi amplifiers generally use two channels for playback, that is, amplify the left and right sound channel signal, and push the left and right speakers to form a stereo sound field. The AV amplifier has 4-9 channels, which promotes multi-channel speakers to form a surround sound field. For example, Dolby AC-3 requires 5.1 channels (left, center, right, left surround, right surround, and subwoofer).
4. Differences in circuit design
In terms of circuit design or circuit composition, the two power amplifiers are quite different. First of all, the high-fidelity Hi-Fi power amplifier circuit is relatively simple and has few signal processing procedures. It is only a combination of amplification circuit and switching and adjustment circuits: AV power amplifiers have more decoding circuits, delays, reverberation circuits, etc. than Hi-Fi power amplifiers, and It is also responsible for amplifying multiple signals, so it has a high degree of integration, complex circuits, and many signal processing programs. Secondly, the AV power amplifier also has a video circuit on the circuit composition.
The main differences between Hi-Fi power amplifiers and AV power amplifiers have been introduced to you. Since the narrative language is more professional and abstract, I will give you a detailed analysis below. If you use AV power amplifiers instead of Hi-Fi What’s wrong with the amplifier?
1. The AV amplifier lacks confidence when playing a large signal sound source
This can be seen from the product manual, the AV amplifier is in the two-channel state The output power is higher than the output power in the four-channel state. However, some manufacturers have the same labeling in the manual. At this time, you can choose music with a large dynamic range for audition, but you can obviously feel powerless. This is because the total power consumption of the AV power amplifier is large, and the power reserve is not abundant, while the Hi-Fi power amplifier appears to be calm.
2. AV amplifier wiring will affect the sound quality.
The AV amplifier is set with a variety of video and audio ports, and multiple sets of audio and video signal sources can be connected. As a result, the signal traces are many and complex, and it is easy to cause mutual interference of the signals. In particular, the existence of distributed capacitance has the greatest impact on high-frequency audio and its harmonics, so that the original rich high-frequency components of high-quality signal sources are attenuated or interfered, so that the listener cannot appreciate the high-fidelity effect.
3. The fluorescent screen of the AV power amplifier will also interfere with the sound quality
The AV power amplifier pays attention to convenient multi-function operation. Intuitive and vivid, but the fluorescent screen is heated by a low-voltage AC filament, and the characters are displayed under the drive of a pulse signal, which will radiate a lot of electromagnetic interference around it, which will obviously affect the sound quality.
The difference between AV power amplifier and HI-FI power amplifier is mainly as above. Another point to note is that although I can give you a list of the differences between AV power amplifiers and HIFI power amplifiers, in reality, the distinction between these two power amplifiers is not so obvious. The average person can’t tell the difference between the two amplifiers at all. So JS took advantage of this and described the AV amplifier as a HIFI amplifier, in order to raise the price. Therefore, when buying power amplifiers, enthusiasts must choose reputable merchants for transactions.
