Why do you need 3 power amplifiers for a home theater?

                          Why do you need 3 power amplifiers for a home theater?

Many home theater users will have doubts in the early stage of purchase. They bought a home theater and thought that one power amplifier would be enough, but the merchant said that the subwoofer needs to add a power amplifier, and the center and surround need a power amplifier. My home also set up a background Sound speakers, so another power amplifier is needed, a total of 3. I said one is enough, they said that the effect is not as good as 3 amplifiers, is that reasonable? Or are they bundling the sales, forcing me to buy two amplifiers that don't make sense?

Isn’t one power amplifier enough? Why does the power amplifier recommended to me need to be equipped with three power amplifiers? Have you been deceived? Here I can tell you first, you are not deceived! Want the best A home theater that restores panoramic sound requires so many power amplifiers! As for why? Don't worry, the editor of Jiaying Villa will continue to explain.

First of all, let's understand the difference between the front and rear stages of the power amplifier:

The professional name of the preamplifier is: preamplifier. It is also the part that has the greatest influence on the tone in the whole set of equipment. It is the equipment that provides the appropriate audio level signal and adjusts the sound quality (commonly known as the preamplifier, connected between the audio source and the power amplifier).

The professional name of the post-stage power amplifier is: pure post-stage power amplifier. This is the real power amplifier part, which has a great influence on dynamics and low frequency control. It is a device that simply amplifies the "pre-stage" audio signal to provide enough power to drive the speaker to sound (always connected before the speaker).

The power amplifiers that are common in general households should be called front and rear stage integrated amplifiers, combined power amplifiers.

Post-stage power amplifier (pure post-stage power amplifier):

The input signal of the rear stage is very simple, it is to undertake the output of the previous stage. But the load of the post-stage is the speaker, which is what makes many audio fans and even magazine comment writers confused. The latter stage is the load of the former stage, which is a high-impedance load; the speaker is the load of the latter stage, which is a low-impedance load. It looks almost the same, only one word is missing, but the high and low impedance makes it easy to push or not to push. The current stage is connected to a high-impedance post-stage, which mainly provides an appropriate output voltage because of the post-stage amplifier.

Post-stage power amplifier (pure post-stage power amplifier):

The input signal of the rear stage is very simple, it is to undertake the output of the previous stage. But the load of the post-stage is the speaker, which is what makes many audio fans and even magazine comment writers confused. The latter stage is the load of the former stage, which is a high-impedance load; the speaker is the load of the latter stage, which is a low-impedance load. It looks almost the same, only one word is missing, but the high and low impedance makes it easy to push or not to push. The current stage is connected to a high-impedance post-stage, which mainly provides an appropriate output voltage because of the post-stage amplifier.

The pure post-stage power amplifier needs a preamplifier to promote it. The power of a pure post-stage power amplifier is generally more than a few hundred watts. It is usually used in some professional places, and multiple units work at the same time to drive different speakers, because it does not have a preamplifier. Therefore, the circuit has no low-level input ports, no jacks for high-impedance input signals such as microphones, which requires adding a preamplifier or mixer to the signal to control it. The preamplifier and the pure post-amplifier are also combined into one, usually with a power of less than 300 watts, which is used in smaller places, such as home use or KTV.

Preamplifier :

A preamplifier is a circuit or electronic device placed between the source and the amplifier stage, designed to accept a weak voltage signal from the source.

The preamplifier is used to amplify weak signals. Generally, the signal is first passed through an electrolytic capacitor to filter out high-frequency noise signals, and then enters negative feedback to amplify the signal. A power amplifier generally refers to amplifying the power of an AC signal, that is, amplifying the current and voltage of an electrical appliance without distorting the signal. The pre-amplifier is close to the detector, the transmission line is short, the distributed capacitance Cs is reduced, and the signal-to-noise ratio is improved. The signal is initially amplified by the preamplifier to reduce the relative influence of external interference. The preamplifier is designed with high input impedance and low output impedance to achieve impedance conversion and matching.

Let's take a look at how to match the power of the power amplifier and the power of the speaker to be reasonable?

First look at the parameters of the speaker. One item is the sensitivity of the speaker, which is the sound pressure level measured at a distance of 1 meter for a speaker with 1w of power. For example, the sensitivity of the speaker is 82dB, then the speaker gives him a power of 1w, which is 82dB at a place of 1 meter.

According to the sound pressure level calculation formula Lp=20lg(p/p0), then every time the power doubles, the sound pressure level will increase by 3dB.

2w=85, 4w=88, 8w=91, 16w=94, 32w=97,..., 1024w=112, 2048=115.

The power of a general speaker is 2000w, which is basically the end. So, if household. The volume you need will not exceed 100dB. So dozens of w is enough.

The indicators of professional speakers will have the following. Sensitivity 1w@1m, rated power and peak power. For example, if the rated power is 1000w (AES standard), it means that the speaker can work continuously at 1000w for 2 hours without burning out. Then the peak power is the maximum power value that the speaker can withstand in a short period of time. This value is about 2-4 times of the rated power, the larger the value, the better the speaker quality of the speaker.

It does not mean that the ratio of power should be matched properly. The larger the power amplifier is, the better. The larger the power amplifier, the higher the output voltage and the better the control over the coil. The matching ratio can only be selected according to the cost performance. If you're super rich, buy the biggest amp you can. If you generally have money, an amplifier with 2 times the rated power is the best choice. If you are a dick, just calculate the required power according to the volume you need, then x2, and just choose the power amplifier.

The sound pressure level of 3dB in physical quantity is also doubled in hearing.

Power amplifiers are generally divided into front-level power amplifiers, rear-level power amplifiers, and combined-level power amplifiers. The combined machine is a machine that integrates the front-level and rear-level power amplifiers. The front stage is used to initially amplify the signal and adjust the volume; while the rear stage is to amplify the signal from the previous stage to drive the speaker.

The independent power amplifier can restore the sound effect of the scene to the greatest extent, such as which side is the wind blowing from? The sound of water flow and dripping water can be played out in detail. Although the combined machine combines the front and rear power amplifiers, this is its The most important disadvantage is that if the front and back stages are played by the same power amplifier, let alone whether the power of the power amplifier can bring the power of the speaker, even if it can, it will not be able to achieve detailed sound. When playing a variety of integrated sounds, the sound will be very noisy, and it sounds like a fake sound, not the sound effect displayed by a real 5.1 speaker.

The best home theater power amplifier is not recommended to use a combined machine power amplifier. First of all, it cannot restore the maximum scene sound effect, and if the power is too high, it will easily burn the machine. But if you are tired and unable to do it, it is easy to damage the strike, and the maintenance cost is high. However, the use of "division of labor and cooperation, each performing its own duties" at the front and rear levels maximizes its unique effects, reasonable work arrangements, and less damage and strikes. It is indeed possible to use a combined machine in a general home theater, but the best combination of sound and power amplifier is two speakers (one type) and one power amplifier. The three power amplifiers mentioned at the beginning are easy to understand.

Well, today’s explanation is here first. If you want to know more or have questions about home theater equipment, film sources, acoustic design, audio-visual room decoration, etc., you can leave a message under the official account to ask questions. We have professional talents to answer. With the help of talents in these industries, we can avoid detours and waste less money. You can add WeChat: hynh00806 free quick consultation!