Second, the speaker is placed on the premise of a good indoor acoustic environment, the more accurate the sound image is positioned, the more realistic the sound is, the more it can show the vivid effect of the sound and image. First look at the placement of the speakers in the theater. The left and right channel front speakers are separated from each other by the same width as the movie screen. The front speakers are usually discharged behind the movie screen, and they can transmit the sound to the viewer through the small gap of the screen. Therefore, this speaker can be placed at half the height of the screen. The subwoofer is not necessarily placed in a symmetrical position in the front speaker cluster; the standard theater has a lot of surround speakers that, together with the front speakers, really "surround" the audience. After referring to the above examples of speaker placement, let's go back and see how the speakers should be placed for the best sound. Here, we have to pay attention to the problem that the indoor play space we encounter may be much smaller than the real theater.
Below, we will discuss the placement of three front (left, center, and right) speakers, then surround the sound box, and finally study the placement of the subwoofer.
1. The center speaker of the center channel speaker is placed as close as possible to the center of the image screen. The center channel speaker has the greatest influence on the sound quality of the movie dialogue, in order to ensure that the dialogue is accurately positioned in the center of the screen and the sound Clear, you should use a separate speaker designed specifically for the center channel, instead of the ordinary bookshelf speakers or the speakers inside the TV. The center channel speakers mostly use horizontal horizontal cabinets, the best placement It is the top of the TV (if the front projection display screen is placed behind the screen), it should be as close as possible to the screen. If the space is limited, a more economical placement scheme can be adopted, that is, no center speaker is provided. At this time, the working mode of the AV amplifier should be placed in the "phantom" center channel mode, so that the information of the center channel is balancedly released from the left and right speakers, and the sound image is just in the center of the screen, which is for the small listening room. This is applicable. Of course, it is best to set up a center speaker.
2. The placement of the left and right channel main speakers has a certain relationship with the position of the center channel speakers. In order to ensure the smoothness of the left and right movement of the sound image, they should be placed on both sides of the center channel speaker, and the three speakers should be at the same distance from the position of the best listener in front of the screen. In general, the center speaker should be placed a little longer than the left and right speakers until the sound field can be completely combined to create a truly unified sound image. The distance of the back is related to the size of the space, the listening position and the speakers used, which can be determined by experiment. In addition, the vertical height of the left and right channel speakers is preferably not higher or lower than the center speaker's axis by 0.3m (preferably slightly lower), otherwise the left, middle and right three The height difference of the speakers is too large, and the front sound image gives a sound jump when it is laterally displaced. Generally, floor-standing speakers can meet the above requirements. If you use a bookshelf speaker for the left and right speakers, you should fix them on the speaker stand so that it meets the above requirements. The distance between the left and right channel speakers leaving the screen depends on the size of the screen. If you use a large, medium-sized screen color TV in a small room, the left and right channel speakers can be placed close to the sides of the screen. If the screen is small, you can make them a little further away from the screen to get a wider stereo field. But don't go too far from the screen, so as not to give people a false feeling because the sound image position is too far from the picture. From this point of view, there is a shortage of "innate" - the environment is too small. In summary, the sound directivity of the left, middle and right three-channel speakers is heavier than the diffusivity, that is, the radiation angle range of the three channels should be oriented toward the optimal listening position. This reduces the effects of reflected sound from the floor, walls and roof, and properly ensures the clarity of the sound image.
3. Surround speaker The surround speaker is used to create an atmosphere, which also plays an important role in the entire speaker system.
A. Types of Surround Speakers Currently, there are two types of surround speakers, one is a common unipolar small speaker, which is usually placed on the speaker stand or hung on the wall. Another type of surround speaker is THX recommended dipole speakers, each with two back-to-back speakers installed, all connected in reverse phase. This kind of speaker only emits high-frequency sound to the front and rear and can not produce low-frequency sound (even Entering the low frequency signal and also not paying the bass due to the offset.) Why is this? Let's look at the working process of the dipole speaker. Two speakers are placed back to back in the speaker, and the two speakers are fed. In the opposite phase of the signal, the A speaker inputs a positive polarity signal, and the paper cassette moves forward, compressing the front air (increased density). At the same time, the B speaker inputs a negative polarity signal, and the low box moves backward, so that The air in front of it is sparse (reduced density), so the direction of the sound wave in front of the two speakers is opposite. If the two speakers feed in the full-band signal, the low-frequency is strong because of its long wavelength, so the low-frequency sound from the A speaker will Winding around The B-speaker is weakened (cancelled); while the medium-high frequency signal has a short diffractive power due to its short wavelength, the mid-high frequency sound on both sides of the speaker is small, so the offset effect in front of the speaker is not obvious, so two The speaker only emits low-frequency sounds in the front and rear, and the low-frequency sound is used. The purpose of using the dipole speaker is to avoid excessive directionality. For the audio industry, the dipole speaker is very strange. Type, this kind of speaker needs a certain development to mature and stereotype. This kind of speaker is not full frequency band, because the frequency below 100MHz has been cut off. The reason why this speaker is used is because it only sounds forward and backward at the same time. Never give a sound to the side of the listener, and let the sound reach the listener before filling the listening room, so that you can create a surround sound that suits people's hearing habits.
B. The arrangement of the surround speakers of the surround speakers should be different depending on the listening environment (room conditions) and the type of loop speakers. The speakers of the left and right surround channels should be more diffuse than the sound. Directionality, which is conducive to create a rich surrounding atmosphere. When placing dipole-type speakers, two factors should be considered: resonance and self-fading. The best anti-resonance is 20% indoor space from the ceiling (or ground). At the height (if the indoor height is 2.5m, the best position is 50cm above and below). In order to make the frequency response smoother, a new device called low-frequency "trap" can be added (absorbing low audio) to eliminate the reflection that causes the sound to self-degrad. For direct-radiation loop speakers, there are many layout options to consider. For example: fixed On the sides of the wall, and point them to the rear corner; fix them on the rear wall so that they open outwards and upwards in an inverted figure-eight shape and face the side wall to the ceiling; placed on the floor against the wall on both sides, And pointing up to the junction of the wall and the ceiling, etc. There are many other options that can be designed according to the specific conditions of the room. The surround sound field of the home theater is mainly formed by the acoustic reflection and refraction of the surround speakers in the interior, and The room acoustic conditions of different rooms vary widely. As long as the patience test and careful comparison, you will find the best placement plan. 4. The subwoofer is usually placed near the front corner of the subwoofer, preferably 1m away from the corner. Above, this can reduce the interference of standing waves. You can also put the subwoofer on both sides of the best listening position and keep the proper distance, because the human ear does not have the directionality of the subwoofers from both sides. Sensitive, so the subwoofer will not interfere with the original sound image localization of the front three channels. Of course, the best placement position should be determined by experiment. The method described below may be helpful for finding the subwoofer. The best position. Put the subwoofer in the best listening position (temporarily remove the nearby debris), connect its speaker cable and play a piece of music with strong bass effect, then listen carefully around the room. When the ear is attached to the ground, it is roughly at the height of the subwoofer. When listening, find the most stable, deepest and clearest point of the bass, which is the best position for the subwoofer.
Bed Vacuum Cleaner : With the beautiful design, this mini Portable Vacuum Cleaner will be good scenery in the house. Small body and high efficiency, the Handheld Vacuum Cleaner is very easy for using and for storage in a small space. You don`t need to worry where to store it. For cleaning the small dust or hair and other small appliances, it will be a very good helper. Of course, this wireless vacuum cleaner also has other functions to remove the dust on table, computer, car, etc. Choose it and you will like it.
Rechargeable Handheld Vacuum cleaner: This Mini Vacuum Cleaner can be used for cleaning hidden dirty of notebook keyboard, printer, pet food, office, kitchen table, or other small household appliances.
Car mini vacuum cleaner: This Usb Vacuum cleaner can be used for cleaning car vent, dashboard, storage cabinet, sand, dust, paper, food debris, and so on.
Rechargeable wireless vacuum cleaner: this vacuum cleaner power supplied by usb port, which is very easy and convenient to use and store.
Easy to use: this mini vacuum cleaners` filter can be washed by water. Just open the dust pot and take it out, then wash it clean and use it again after it dry.
Bed Vacuum Cleaner
Bed Cleaning Robot,Vacuum Cleaner For Bed Bugs,Bed Bath And Beyond Shark Vacuum,Bed Bath And Beyond Vacuum Cleaners
SHENZHEN HONK ELECTRONIC CO., LTD , https://www.honktech.com