How to choose power amplifier for home theater audio

Since the craze of home theater landed in China, there has been a whirlwind of AV in China. With the vigorous promotion of audio manufacturers and the help of enthusiastic people, the word AV has firmly taken root in the hearts of audio lovers. When configuring audio equipment, it is often said that words must be called AV and words must be called home theater. It seems that everyone is already an AV fan. How to tell whether an AV amplifier is good or bad? What are the purchase elements of AV power amplifier? Please allow me to speak slowly.

How to distinguish the quality of a power amplifier?

AV power amplifier is the core of audio playback, and its function is multi-channel sound playback. When it comes to multi-channel playback, it is inseparable from the standard of surround sound. When choosing a power amplifier, be sure to pay attention to whether the power amplifier has the current popular surround sound standard certification:

1, Dolby prologic surround sound.

2. dolby digital surround sound.

3.DTS surround sound.

4.THX surround EX surround sound (7. 1 channel).

5.DTS-ES discrete surround sound (6. 1 channel), etc.

A home AV amplifier should at least have the function of decoding and playing dolby digital surround sound, because dolby digital is the mandatory audio standard for PAL DVD set by DVD Alliance in May 438+0997+February, and whether the AV amplifier has this function is the basic point for users to choose. Other certifications directly reflect the power amplifier level.

In addition to obvious certification, there are many indicators and parameters to evaluate the quality of an AV amplifier.

1, output power: refers to the energy obtained by the speaker connected with the power amplifier. For the power amplifier, its rated power (the effective value power that the power amplifier can continuously output without distortion) is an effective index to evaluate the performance of the power amplifier.

2. Distortion: The output of the equipment cannot completely reproduce its input, and the distortion of waveform or the increase or decrease of signal components is called distortion. The smaller the distortion of the power amplifier, the better the sound quality.

3. Dynamic range: the level difference between the strongest part and the weakest part of the signal. For a device, the dynamic range indicates the device's ability to respond to strong and weak signals.

4. Damping coefficient: Damping coefficient refers to the ratio of load impedance to amplifier output impedance, which is a performance index to measure the damping effect of amplifier internal resistance on speakers.

5. Output impedance: The output impedance of the power amplifier refers to the equivalent internal resistance of its output to the speaker, which should be consistent with the rated input impedance of the speaker.

6.SNR: SNR refers to the decibel difference between the audio signal level and the noise level. The higher the signal-to-noise ratio, the smaller the relative noise of the amplifier and the better the sound quality.

7. Degree of separation: Degree of separation refers to the ability of the surround sound decoder in AV power amplifier to restore the audio coded signal to each channel signal. The power amplifier with poor separation will have the phenomena of inaccurate audio-visual positioning, insufficient sound field and poor audio-visual coherence.

Perhaps these indicators confuse ordinary people. Simply put, the most intuitive is the driving ability (that is, power) and the weight of the power amplifier. Although the relationship between output power and driving force is not so direct, there is a close relationship. The output power can be easily found from the indicators in the manual, 100W, 200W, 400w or even more, but the driving ability sometimes needs to be really heard from behind these indicators to have a real say. This is about the choice of the speaker. The rear power amplifier drives the speaker. The stronger the driving ability, the easier it is to control the speaker and tap the potential of the speaker. Therefore, the average American AV amplifier is as big as the cars they produce, and it is easy to drive low-impedance audio with high power. The AV amplifier produced in Japan occupies more than 80% of the market, which also shows the uniqueness of its technology. Therefore, it is very important to use high-power post-amplifier as much as possible in exchange for more leisurely control and instantaneous dynamics. When it comes to the weight of the power amplifier, it is probably the easiest to perceive. Because the power amplifier needs strong power support, the heavier the power amplifier, the larger the transformer index of its power supply equipment or the larger the capacitor used. These are the guarantees of the quality of the power amplifier. The heavier the power amplifier, the better its stability, and the influence of unnecessary vibration on the sound quality can be avoided.

Considerations for purchasing an audio amplifier

1, decoding function

Generally, the combined AV amplifier with built-in decoder should be selected, and at least dolby digital and DTS decoders should be provided to ensure that it can adapt to the playback of sufficient audio and video resources.

Dolbydigital (Dolby AC-3) is an all-digital separated multi-channel movie soundtrack system introduced by Dolby Laboratories in the United States, also known as dolby digital surround sound. It is a high-quality digital audio coding format, which is more advanced than other methods in the past. All channels are recorded in full digital mode, and efficient MPEG2-2 digital compression coding technology is adopted. Dolby digital surround sound system has the following advantages: true stereo surround sound, wide frequency band of full audio range, complete isolation of each channel, extremely wide and controllable dynamic range, and compatibility with existing sound systems.

DTS(Digital Theatre Sound) is a multi-channel digital surround sound system for home use introduced by DTS Technology Company of the United States. It can improve the sound effect of multi-channel surround sound, exceeding the CD standard of 16bit quantization in dynamic range and high fidelity. The compression ratio of DTS system is not as high as that of dolby digital, and the adaptive bit rate range is wide. It can compress 18bit, 20bit, 22bit and 24bit respectively (the input signal can still maintain the complete dynamic range and frequency band), and the sampling frequency can be 48kHz, 96kHz or higher. DTS system adopts 5. 1 channel format like dolby digital, but it can reach 8. 1 channel at most. In terms of sound quality, DTS and Dolby Digital are neck and neck. In addition to LD and DVD discs, DTS system also has four-channel or six-channel recorded CD discs, while Dolby Digital only has DVD discs and no CD discs. The software and hardware of DTS system are printed with DTS special logo.

2. Power matching

The focus of AV power amplifier is to create an ideal listening environment with visual effects, and to create a realistic sense of orientation, presence and shock. Therefore, the design of AV power amplifier focuses more on expressing the clarity of dialogue and the dynamic "explosive" effect of audio-visual environment, restoring or simulating the sound field positioning of audio-visual integration, and creating various sound field atmospheres. In this way, AV power amplifier is not only required to have wide frequency range, low distortion, high signal-to-noise ratio, good transient characteristics, beautiful sound quality and timbre. , but also pay more attention to the sound pressure level, that is, to ensure adequate output power under the premise of low distortion.

The unit of output power of power amplifier is Watt (W). Because different manufacturers have different measurement methods, there are some different names. Such as rated output power, maximum output power, music output power, peak music output power, etc. The rated power of the front main channel of the advanced AV amplifier is generally above 80W to meet the requirements of sound pressure level 107dB of the cinema.

In general, the greater the power of the amplifier, the better. However, the main function of the power amplifier is to push the speaker, so the rated output power of the AV power amplifier should be determined according to the driving power required by the speaker. Generally speaking, the power configuration standard of power amplifier and speaker is: under certain impedance conditions, the power of power amplifier is greater than that of speaker, but not too large. In general application, the distortion rate of the power amplifier should be about 1.2- 1.5 times of the rated power of the speaker; In the case of large dynamic, it should be about 1.5-2 times. It should be noted that the maximum output power of the power amplifier and the maximum bearing power of the speaker must be well matched to prevent the speaker from being accidentally burned.

3. It should be noted that the requirements of AV power amplifier and HiFi power amplifier are different.

Hi-Fi equipment is mainly used to listen to music, and the highest purpose is to reproduce the information on audio software, so the materials used are more particular, and the higher the power, the better. The purpose of AV equipment is to obtain the best sound field effect, the momentum and atmosphere required by the image, and the sense of scene expressed by the image, so it pays more attention to power and dynamic response. And they don't pay much attention to the sense of music, so some Hi-End HiFi amplifiers are not necessarily suitable for AV amplifiers.

4, debugging to understand the performance and sound quality, is a necessary part of purchasing AV power amplifier.

The performance of the machine has a great relationship with the quality. To know the quality of the product you choose, you must try it out yourself and actually operate it once to clearly understand the performance of the machine. As for the sound quality, no matter how good the parameters are and how complete the functions are, the power amplifier will be used to restore the sound. We don't want anything that will make noise when we move home, so no matter how much preparation you make before buying an AV amplifier, you still have to listen to it yourself. Many times, the sound of the power amplifier has a certain personality, and the sound matching with the speaker is not necessarily good. So you should not only audition in person, but also connect the power amplifier with the speaker system you choose for on-site audition.

5. Try to choose a new model.

Because the technology involved in AV power amplifier is complicated, among which IC chips are introduced quickly, and the new IC chips are definitely superior to the old ones in technology, so the newer the model you buy, the newer the technology you can enjoy. At the same time, it is suggested that it is best to choose AV amplifier products above the mid-range to better meet the audio-visual enjoyment needs of home theaters, so as not to feel like chicken ribs after buying them.

6. Brand and after-sales service

We should purchase products of famous brands through formal channels, such as Yamaha, Tianlong, Qiao 'an and marantz. Product quality and after-sales service are relatively more secure. If you buy online, you'd better go to a physical store to audition to determine the brand model, and then choose a well-known B2C mall, brand official website or flagship store to buy through the price comparison of hundreds of searches. com。 Also, remember to buy an optical fiber cable to connect the player and the AV center after buying the AV amplifier, otherwise the dolby digital decoder of the AV amplifier cannot be used. Top ten AV amplifier brands >>