Is it necessary for home cinemas to go up to the rear power amplifier?
What is the latter? Before we talk about the role of the post-level, let's first give the newcomers a scientific popularization of what is the post-level. When it comes to 'post-level', there is a corresponding 'pre-level '. The narrow front stage refers to the front stage amplifier, which is mainly responsible for decoding, balancing, polishing, voltage amplification and other functions of signals from the sound source, and then sending them to the back stage amplifier. The post-stage or post-stage power amplifier is responsible for current amplification of signals transmitted from the front stage. Another is the subversive power amplifier, which is equivalent to integrating the front and rear functions into one machine ( Things that integrate multiple functions are generally not so good, focus can produce good results). Features of rear power amplifier (Citing Baidu Encyclopedia) : The input signal of the latter stage is very simple, that is, to undertake the output of the former stage. But the load at the back level is the horn, which is what makes many audio fans and even magazine reviewers uncertain. The latter stage is the front stage load and is a high impedance load; The horn is a rear load and a low impedance load. It looks similar, only one word is missing, but one high and one low impedance causes 'easy to push' or 'unable to push. The current stage is connected to the rear stage with high impedance, which mainly provides an tangent output voltage, because the input impedance of the rear stage expander is rarely lower than 10K Ω. There is such a rear stage, but it is rare, generally, it is about 47K Ω. When the rear stage expander is connected to a low impedance horn, it must not only provide an tangent voltage, but also provide sufficient current. Except for a few special cases, the current horn impedance is rarely higher than 8Ω or even lower than 4Ω. And 1 kΩ = 1000 Ω. Is there a big difference? So Hi- End post-stage, not only emphasizes high-power output, but also hundreds of watts, each channel is independently packed, and it is specially marked as a high current design. When the load impedance is reduced by half, the output power will be doubled to the original. If the output current capacity is insufficient, when the load impedance decreases ( When some speakers work, such as Dynaudio, their impedance decreases as the signal frequency decreases) If the output current of the expander is not enough, cutting-clipping will occur. Here are some common questions from friends about the latter stage: Q: What is the meaning of increasing the latter stage, will the sound quality be improved? Old snail: In the era of market economy, everything has been guided by market demand. The intuitive performance in the audio and video industry is that many users want to buy equipment at a lower price. For example, many power amplifier manufacturers deliberately produce low workmanship and shrinking materials in order to cater to consumers, the equipment with insufficient power, after the user bought it back, found that the performance of the speaker could not be played at all. The sound was soft and weak, and the water was muddy, and the power calculation standard of the Japanese power amplifier was too pit (Not just unintentional or intentional) The power value in the parameter divided by three is almost the standard power size ( For example, a certain Anqiao power amplifier has a marked power of 120 w, which can actually reach 40 w) It is in this case that the role of the latter stage is highlighted. By adding the latter stage, the sound effect can be greatly improved, the more obvious feeling is that the sound volume is more sufficient, the big dynamic is free and easy, and the sound details are better. Compared with the low-end portable power amplifier, the high-thrust rear stage is like the difference between Lamborghini sports car and ordinary home car engine ( The premise is that your body and tires can withstand and reach the corresponding grade, otherwise it will not be upgraded) , Strong power can give you a shocking experience of 'flying on the ground' and ordinary family cars can also run, but if you want to speed up, you will always be unable to cope with it. It can only be a walking level, there are also users who don't understand who use very low-end power amplifier to push the large floor-to-ceiling box, barely able to make a sound, and the sound effect is a mess. This is the consequence of the 'small horse-drawn cart. Q: Is the volume particularly high after using the rear stage? Old snail: this is a misunderstanding of many entry-level users. It can be understood that the volume is positively related to the power and sound pressure, but it is not a proportional increase. Laoding's example is very good: The opening angle of a tap (Equivalent to the position of the volume knob) Does not represent the size of the water flow, people must be based on the actual feeling of the water flow (Ear feeling) To adjust the faucet, I haven't seen anyone who will scale the faucet every time according to the scale. In fact, the angle of rotation of the faucet is not only related to the structure of the outlet of your faucet itself (Equivalent to the magnification gain of the latter part), But also related to the water pressure before entering the faucet (Equivalent to the level of the previous output). I don't see the faucet in some places. The water flow is still very small! The effect of increasing the rear stage is that the water flow is thicker, and the hand is washed to feel the water flow is full and comfortable. Q: What is the right situation to increase the rear level? Old snail: Please note that not everyone needs the latter stage. It is wishful thinking to blindly think that increasing the latter stage will double the effect. One of the most important parameters is sensitivity, if your speaker sensitivity is above 90, the gallbladder machine can be pushed very well, the budget is limited, and you can buy a hair back, and often someone asks me what kind of friend is a certain model of Wei, I recommend you to understand the latter level. Some speakers are really not easy to push. You need to increase your budget on power amplifier. If you have a speaker that is not easy to push, adding a rear level should be greatly improved ( What does it mean to push the sound box badly? See: What does it mean to push the sound box badly and why is it difficult to push it? ' http://www . Hdav. Com. Cn/play- Homethology/20150609_2495. Html): 1. It already has a subversive power amplifier with a front-level output and plans to upgrade it to improve sound quality at a lower cost; 2. Set up a home theater or high-fidelity HIFI audio system to achieve high quality results; 3. Hope has been family theater effect comprehensive improve buy pre-level of style get powerful power.