How to choose a home theater amplifier? Reasonable matching is very important

How to choose a home theater amplifier? Reasonable matching is very important

The home theater AV amplifier is an important part of the home theater system. It plays the role of the control center in the entire system. It serves as a link between the previous and the next on the line, driving the speakers to play sound and maximizing the effect of the entire home speaker system. So how? Choosing an AV amplifier is very critical.

01: Matching of equipment of the same grade

There are many types, brands, and models of AV amplifiers. The performance indicators of the AV amplifier should be close to that of the equipment it is connected to, otherwise it will cause waste. For example, when a high-end AV amplifier is paired with a signal source with a poor signal-to-noise ratio, it will only make the noise emitted greater, and it will truthfully expose the various shortcomings of the low-end signal source. Similarly, when using a low-end AV amplifier to match a signal source with very high performance indicators, it will be difficult to bring out the best of a high-quality signal source.

02: Investment ratio recommendations

When equipped with an AV system, the investment ratio of each part should be appropriate. Among them, many audiophiles believe that the impact of audio equipment on sound quality is basically as follows: speakers account for about 40-50%, signal sources account for about 20-30%, and amplifiers account for about 30-35%. It can be seen that speakers have the greatest impact on sound quality, and investment should focus on speakers, but the above ratio cannot be directly used as an investment ratio mechanically.

03: Matching with speakers

The degree of matching with the speakers is directly related to the music playback effect and the life of the equipment. Matching mainly refers to damping matching, impedance matching, power matching, etc. In fact, factors such as the sensitivity and timbre of the speaker also have a certain impact.

(1) Impedance matching

In matching, impedance matching is the first priority. The speaker is the load of the power amplifier, and the rated impedance of the speaker should not be less than the rated load impedance of the amplifier. For example, the power amplifier was originally designed to be connected to an 8 ohm load and should be connected to a speaker with an impedance of 8 ohms or around 8 ohms. When connected to a 16-ohm speaker, the output power is usually reduced by nearly half, and the impact on other indicators is not obvious. However, when connected to a 4-ohm load, under ideal circumstances, the output power is nearly doubled and the distortion is significantly increased. Transient characteristics are reduced. If the volume is turned up very high, high-power transistors may be damaged. Some power amplifiers allow a variable range of speaker impedance, such as 4-16 ohms. At this time, every time the impedance is reduced by 1 times, the power can be increased to 1.6 times. If the impedance is calibrated to 8 ohms and the amplifier has a rated output power of 100W, if When changing to a 4 ohm impedance speaker, the amplifier output power should be 160W.

Usually, when matching the impedance of a transistor amplifier and a speaker, the impedance value of the speaker is not very strict. But for the tube amplifier, it works in a high voltage, low current mode, and the speaker driven should be strictly consistent with the impedance value of the power amplifier design.

(2) Power matching

Power matching means that the rated power of the power amplifier is compatible with the rated power of the speaker. Generally, it is more appropriate for the rated power of the amplifier to be one-quarter greater than the rated power of the speaker. For example, a 125W amplifier should drive a 100W speaker. Actual speakers also have a certain ability to withstand overload, and their allowable value can reach about 2 times the rated power.

Since the load capacity of the tube power amplifier has soft characteristics, its overload capability is strong. Even when overloaded, the distortion does not change much, so its power reserve is smaller than that of the transistor amplifier. For example, all things being equal, a 60×2 transistor power amplifier can match the power capability of a 100W×2 transistor power amplifier.

(3) Understand the difference between AV amplifiers and pure power amplifiers

There are many differences between AV power amplifiers and pure power amplifiers. The most obvious one is the number of power output channels. There should be at least 5 channels of AV power amplifier output channels, namely the front left and right main channels, the center channel and two surround channels. Channels, more can reach 11 channels or even some high-end power amplifiers can reach 32 channels. It can decode ordinary stereo sound into multi-channel panoramic sound and other sound formats and transmit them to the speakers. In addition, the AV amplifier also has a video decoding function. It can decode ordinary standard definition sound. The signal is output to a TV or projector as a 4K or even 8K signal through frequency multiplication decoding. Pure power amplifiers only have single-channel output or dual-channel output, and only output power without decoding function.

When choosing a power amplifier, you must pay attention to distinguish their functions. AV amplifiers are used for watching movies, listening to music and other audio and video. AV amplifiers of international brands basically do not have karaoke functions because their usage scenarios are different. AV amplifiers require transparent and delicate sound and do not have high power requirements; Professional power amplifiers such as karaoke entertainment require large power, large thrust, relatively thick sound, and strong strength; as for the movie K power amplifier, it can only have relatively complete functions. Compared with AV power amplifiers and professional power amplifiers, it is a pure power amplifier due to insufficient capital budget. It is an entertainment product, not professional.

     I believe that if a professional is specialized in taking into account reverb, surround, karaoke and other functions, it is impossible for it to work hard on the technical specifications of the power output circuit. Often the performance in all aspects is average, and the music effect may not be ideal. , and it is easy to cause interference between various parts of the circuit.