How To Choose The Pre-amplifier, Post-amplifier, And Merged Amplifier?

- May 28, 2020-

Many friends want to get started with Hi-Fi or home theater. TVs, projectors, speakers, etc. are all easy to handle, but once you get to the amplifier, it is completely a bottleneck. Don't understand, what is pre-amplifier and post-amplifier? What is a combined amplifier? What's the difference? Is there a difference between home theater use and pure Hi-Fi use? These are the roots of the problem. In order to ensure that everyone can get started clearly and clearly, let's do a detailed introduction.


What is a power amplifier?

Since you want to assemble a home theater, you must first understand the function of each equipment, and the power amplifier is no exception. You have to know what it does and what it does.


Amplifier, the accurate saying is receiver, amplifier, English is Receiver, which means receiving audio and video signals and processing to obtain better audio and video effects output to video equipment (TV, projector) and audio equipment (speaker) However, domestic unification is collectively referred to as power amplifier.


Why do you need a power amplifier?

Some people may ask, why do I need an amplifier? The player is directly connected to the TV and speakers, is there no sound in the picture?


In theory, there is no problem, but for Hi-Fi and home theaters at this stage, the power amplifier is not just as simple as power output. For Hi-Fi, it needs to analyze the basic sound as much as possible. Restore the sound effect, and then amplify it to let the speaker emit sound to ensure the output of sound quality details. For home theaters, it is more realistic, it can achieve the separation of audio and video signals, and then decode and picture quality sound quality Enhanced processing, and finally output to TV / projector and speakers, has achieved a more perfect effect.


Another point is that the signal source input interface and output interface of the amplifier is obviously more than that of the player. If you have more equipment, the amplifier can help you integrate management and switch output.


What are the application scenarios of the power amplifier?

It is divided into professional power amplifiers and civilian power amplifiers in the horizontal direction, and Hi-Fi power amplifiers and A / V home theater power amplifiers in the vertical direction.


Professional amplifiers, as the name implies, are mainly used in large professional venues such as conference halls, performance halls, music halls and even movie theaters, and ordinary audiences do not need to consider them.


Civilian power amplifiers are better understood, that is, we use them at home, or in some small dining rooms and parlors. Due to site constraints, the output power of these power amplifiers is generally not too large.


Civilian power amplifiers are divided into Hi-Fi power amplifiers and A / V home theater power amplifiers. Hi-Fi power amplifiers are mainly used for audiophile music, while A / V home theater power amplifiers are used for family movie watching. Compared with Hi-Fi, the effect is not so good.


What are the pre-amplifier, post-amplifier and combined amplifier?

Whether it is Hi-Fi or A / V, both power amplifiers are divided into pre-amplifier, post-amplifier and combined amplifier.


For Hi-Fi, the pre-amplifier is more for audio signal reception, volume adjustment and basic signal amplification, while the post-amplifier is simply used as an output amplifier with higher power. The output can be launched as long as there are enough good speakers Good results. Combined power amplifier refers to the combination of front and rear power amplifiers, not only for audio signal reception and processing, but also for high-power output amplification. Hi-Fi's pre-amplifiers are divided into active and passive. The active pre-amplifier amplifies the signal through the power supply, while the passive pre-amplifier only has the effect of adjusting the volume. But now there are very few passive preamps in this era, because the internal resistance of the sound source and the rear stage is very different. Only a volume switch connects the sound source and the rear stage. , Frequency effect is lost! In addition to adjusting the volume, the active front stage can also be used as a preliminary amplification and to reduce the internal resistance between the sound source and the rear stage, that is, as a buffer.


For the A / V home theater amplifier, the role of the pre-amplifier is more powerful. It receives audio and video signals, and performs audio and video separation, decoding, and optimization processing, so that the video and audio can be obtained without interference. Pure signal output. The function of the second-stage power amplifier is the same as that of Hi-Fi, as the effect of audio output amplification. In the same way as merging power amplifiers, the front and rear stages are combined together to separate audio and video processing, decoding, etc., while taking into account the power amplification output.


For the rear-stage amplifier, all it needs to do is to give the signal from the front stage to the speaker, that is, the speaker, not to say that the louder the better, but the need for "enough power", which refers to "enough power" Refers to the ability to guarantee the sound of the scene Hold, without losing the details.


Can't the A / V amplifier bring HI-FI?

No, it's just that it is more complicated in design and line output than Hi-Fi amplifier, which makes the purity of the sound more interfered. The good point is dyeing, and the bad is destroying the sound purity. In this case, the possibility of A / V power amplifier taking into account Hi-Fi is relatively low. In other words, if you want both the effect of a home theater and Hi-Fi, then you better have to match two different The former level, but the latter level can be the same.


Is it better to have separate power amplifiers before and after, or to combine power amplifiers?

Generally speaking, separate front and rear power amplifiers are better. First, separate front and rear power amplifiers can have their own space to make more precise, and the materials will be more sufficient. Second, due to the separate processing, mutual There is less signal interference between them and more detailed performance. The combined power amplifier is indeed at a disadvantage. Even the top-level combined power amplifier is not as good as the top-level independent front-end power amplifier.


If you really want to choose, how to choose?

The first thing that needs to be clear is that almost all current manufacturers are mainly pushing and combining amplifiers, because there is only one machine, which is simple to set up, easy to adjust, easy to use, and very friendly to entry-level players. The independent power amplifiers before and after the class belong to senior players who prefer to play, because they can make different customized solutions by themselves, the adjustment is more diversified, and the play is more slippery.


Secondly, there is a flaw in the merged amplifier, that is, the upgrade, especially in the aspect of A / V home theater, the emergence of various new formats, so that many old amplifiers can not get the upgrade they deserve, at this time you want to upgrade the amplifier, you You have to change the machine. But the front and rear power amplifiers are different. The latter level is generally not upgraded too much. Under the premise of sufficient use, the latter level does not need to pay attention, only need to change the previous level. Of course, this cost still needs to be calculated.


In short, if you are an entry-level player, the merged amplifier is actually enough, because it is also divided into high, medium and low grades. For senior players, I believe that independent front and rear amplifiers are more suitable for them, because they can match the combination they need according to local conditions Get different audio and video experiences.