Standard THX home theater renovation process (multiple pictures)

Standard THX home theater renovation process (multiple pictures)

Private cinemas, private wine cellars, and private cigar rooms have become the hallmarks of the current villa owners' taste of life. As the biggest bright spot in the villa decoration, the home theater decoration market is in full swing...

Faced with this high-growth emerging market, a large number of professional home theater engineers have emerged through extensive training. The quantity and scale are unprecedented. However, we still have a big gap in the renovation of home theaters abroad. Many links in the decoration process are not matched, and the quality of the decoration is uneven.

The author introduced a detailed foreign home theater renovation construction process, so that everyone can see the standard of foreign home theater decoration.

See the word document for the picture in the text: "Standard THX Home Theater Decoration Process" (multiple pictures).

Home Theater Decoration FAQ:

Why do you need to acoustically treat the room?

A: If the room is not properly acoustically treated, it may cause hundreds of thousands of sounds to sound the same as tens of thousands of sound effects. For example, if the power amplifier or speaker above 10,000 yuan is pushed with 1W power, the sound is basically the same, and everyone is satisfied. However, if you increase it, the sound quality will be different. However, if the room where the equipment is placed is not ideal, the acoustic defects of various rooms will cover the original sound quality of the equipment. Just as the Hummer is not as good as Alto in the city center. Therefore, to buy equipment, you must invest a certain amount of money to correct the acoustic structure of the room, in order to hear good sound.

I always heard that the first reflection zone is very important. What is it? What should I do?

The sound from the speaker is directly heard into our ears, and the sound reflected by the object is called the reflected sound. Because the human ear has a "has effect" of binaural positioning. This is why the two speakers sound like they are in the middle. This is also called the sound field positioning, but because the wall reflected on the sides of the speaker has the shortest distance, the sound is transmitted to the human ear very quickly. It may be within 10ms (this is called the first reflection sound), which will interfere with our normal two masters. The middle sound field of the speaker is positioned, causing the sound image to be unclear. This is what we must overcome.

Our approach is to absorb the sound in the area of ​​the first reflected sound to weaken the sound. Generally, the first reflective area mainly appears on both sides of the wall, as well as the ceiling and the ground closer to the speaker. Therefore, it is possible to perform sound absorption or diffusion treatment in these areas.

Where is the first reflection zone located?

The first reflection zone is at a distance from the direct acoustic path plus 3.5 m. On both sides of the wall, there are ceilings and floors closer to the speakers.

The diffuser, as its name suggests, allows the sound waves to spread evenly into the space, whether in a theater or concert hall or studio or in a home listening room, except for a more condensed sound, more accurate positioning, better faxing, and overall sound field. Surrounded by the creation, the sound is more delicate and profound!! Is the best tuning tool!

Design Theory: Designing this diffuser made of wood, in fact, the same mathematical principle used for the two-dimensional original root diffuser made with styrofoam. The prime number used is 31, and they use 157. The different places are the materials used, one for styrofoam and the other for wood. Basically, the reflection coefficients of the two materials are different for the sound wave. The sound wave reflected by the styrofoam is limited. Although the incident wave in one direction can be reflected into 157 directions, it is effective only for the higher frequency band, so the effect is very limited. The wood made this, although only the sound wave is diffused in 31 directions, but the amount of reflection is sufficient, and I set the frequency band at 900hz~3.4Khz, the purpose is to make the intermediate frequency more transparent, thicker and warmer. The Arbiter two-dimensional design not only widens the left and right sides of the sound field, but also makes the sound field high and low. The above is the conclusion made by computer software simulation, the effect is really good.

Hard and soft style of the main wall

There has been controversy about whether the processing behind the speaker is hard or soft. In fact, each has its own style, hard processing, can be a light wall, exquisite can be built with large cobblestones, or thousands of shale. This really creates a sense of space, and a better musical taste for the delicate stereo bookshelf.

For the theater, soft processing is more suitable, because it can hear more direct sounds and avoid the interference of reflected sounds, which can be said to be original. Because some reverb effects and space effects are actually preset in the recording. There is no need to rely on the reflection space to give extra delay processing. Of course, for a small power speaker, if there is too much sound absorption, there is a feeling of dryness, but the cinema sound power is too large, and the sound energy is sufficient, so it is more suitable for soft processing of the wall (sound absorption instead of diffusion).

What is the echo?

In large rooms, it is possible to generate a reflected sound with a delay of more than 35 milliseconds. This kind of sound is called echo, which will destroy the playback effect, especially the percussion will cause serious interference.

In a small room, there are hard parallel walls that produce a short, continuous echo flow (which can be called a vibrating echo).

The factors that produce these echoes are the hard-radiated surfaces of transparent glass doors and windows, bare walls, floors, ceilings, etc., so that a series of tremor echoes occur in the surface of the listening room, sometimes a reflection It is reflected back to the listening area, and the original sound is reproduced, which is eliminated.

The design principle of LEDE is a common design principle in the listening space of the studio. His basic principle is that the wall behind the horn should be treated with strong sound absorption to minimize the reflection. This is DEAD END. This way, the studio can directly hear the direct sound from the horn, thus mixing Sound and recording have a correct judgment. So why do our audio-visual rooms use this method? Because the film source in our movie is the various effects and reverbs configured from the studio. It is also hoped that the listener can hear the direct sound to ensure the original effect. Other walls have to do some diffusion of sound waves. This is LIVE END, because the space in the studio is too small, and if it is all sound, the sound is too dry.

Many enthusiasts are talking about the harder the wall behind the speaker. Is this not the opposite of LEDE?

If we pursue the feeling of the concert hall, it should be done. There is also the difference between the speakers, the electronic active crossover speaker used in the studio or in the theater is too large and the sound can be sucked away by the wall. If you use a small bookshelf, you will inevitably eat a lot of power, and the sound will be weak.

About home theater decoration case

Home theater decoration DRY twelve elements should pay attention

"AV 20", the part of the sound effect is "Conversational Authenticity", "Circular Surrounding", "Upper Sound Field Performance", "Moving Sense", "Positioning Sense", "Speed ​​Sense", "Impact" Ten items such as "low frequency control power", "space sense" and "detail performance".

Conversational truth

Why do I have to put the trueness of dialogue in the first item? Perhaps many people will think that the dialogue sound in the movie has no knowledge, far less than the sound of bullets or explosions. Actually not! You can think about it. In a movie, how many different kinds of environments, different distances, different subjects and slaves have to do with the dialogue effect? ​​It is really a huge and annoying job. With my own experience of watching DVDs and DVDs for many years, I found that if the dialogue sound of a film is very delicate, the other sound effects will not be worse. On the other hand, in a film with a large sound effect, which is casual and not paying attention, the strong sound effect part may also be sound only and not texture.

In addition, there is a very important factor, that is, in the surround channel sound, the sound effect shared by the center channel can be said to be the heaviest weight, and then the subwoofer. The most important front channel in the two-channel era is almost just the same as the surround channel. So, you have to buy the best mid channel, and the sound of the surround channel can be expressed. If you put most of your budget into the front channel because of misunderstanding, and let the middle channel just talk about a small "small thing", then you will put the cart before the horse.

Perhaps you will wonder why the sound engineer wants to put most of the sound on the center channel. It's no surprise that when the film is filmed, the photographer will arrange the main scene in the center or edge of the screen. Of course, the center of the screen. Since the center of the screen is the main activity of the plot, most of the sounds will be arranged in the center of the screen. As a result, the importance of the center channel is nothing strange.

What are the delicate sound effects of dialogue? That is the combination of dialogue and environment. In what kind of environment, dialogue should show a consistent sound effect. For example, the dialogue in the cave should have the echo effect in the cave; the dialogue in the room or in the hall should have different sound effects; many people should have a delicate sense of distance at different distances. As the screen shot shifts, the dialogue sounds will also have different delicate features, which is a change you can notice.

In general, most of the dialogue is responsible for the middle channel, but the front and surround channels also have a decisive influence on the delicate changes in the white sound. Those who watch movies on direct-view TVs may not be as focused on the big screen as the screens are smaller because of the smaller picture. In any case, the authenticity of the white sound effect should be consistent with the experience of our daily life, which is why you can easily expect it.

Surrounding sense

Looking at AV, most people will focus on the drama, supplemented by pure music. Therefore, it is very important to surround the scene. Ordinary people's surround system, or the surround sound of a typical movie, the biggest flaw will probably appear in the surrounding "gap" between the front channel and the surround channel. This surrounding gap makes it impossible to continuously lack the surround enclosing effect after the trip, that is, the surround sound is concentrated at the front end and the back end, but the middle is weak.

A good surround envelopment senses that there is no gap after the trip, and the various sounds will closely surround you. If you feel that the sense of envelop is weak, the problem may appear in three ways. One is the problem of the processor of the AV amplifier itself. The second is that the processor itself is of sufficient quality, but your parameter settings are problematic. The third is that there is a problem with the 5.1 channel speaker placement.

Some people may wonder if there is not enough surround encirclement because there is no surround array of multiple surround speakers or no rear center channel. Of course, 6.1 or 7.1 can give you a better sense of rear surround, which is beyond doubt. However, I can assure you that the normal 5.1 channel is enough to show a very good sense of surround, including the above sound field performance will not be a problem.

Upper sound field performance

The performance of the upper sound field is probably the most eager, most attractive, but also the most difficult place to play AV. What is the performance of the upper sound field? The sound effects that will fly around you are the performance of the upper sound field. Moreover, the upper sound field is not only on top of your head or on the top of the front channel, it should appear above your entire space. In other words, it fills up your ceiling space, which is the real upper sound field.

The simple upper sound field performance is that the sound flies around the head. The higher-order upper sound field is the oblique and lateral sound movement. The highest level of the upper sound field is that the sound stays somewhere on the ceiling. In view of the quality of various surround sound decoders, as long as there is no problem with the speaker placement, there should be no problem in reproducing the wonderful upper sound field.

Mobile sense

The sound moving effect of the sound produced when an object moves in various directions in space is called a sense of movement. If the sound is moving, we will feel that the film is more realistic. On the other hand, if the sense of movement of the sound is not true enough, we will not feel addicted when we look at the movie. In order to make the sound movement feel real enough, in addition to the delicate processing of the recording and the quality of the processor, the placement of the speaker is also very important. Especially the relationship between the front channel, the center channel and the surround channel. The height of the center channel is preferably the same as the height of the front channel (only the center point of the treble and the mid-range sound), and the surround channel is not as high as possible, and it is not as good as 180 cm from the ground. Good effect. All of this must be adjusted according to the actual situation of the space.

Sense of positioning

The so-called sense of positioning is the clear feeling that "the sound that does not move" gives you a position. It focuses on the correlation of sounds in a variety of different locations. Take the bullet launch as an example. When the gunman puts the bullet on the cymbal, the sound is fixed, it is the sense of positioning. When the trigger is pulled down, the sound becomes a sense of movement after the bullets fly out. When the bullet hits the wall and bounces to another place, it is also a sense of movement. After the bullet is fired, the sound of the shell falling to the ground is the sense of positioning. At this point, you can clearly hear the shell falling at a certain point. The clarity of positioning is like whether the focal length is clear or not, but the former is the feeling of hearing, while the latter is the visual feeling.

Sense of speed

The speed of response of various sounds can be called the sense of speed. The sound of the vehicle flying in front of the feeling is the portrayal of the sense of speed; the powerful sound emitted by the bullet is also the expression of speed; the hammer hitting the wooden board is also a manifestation of speed. In short, the sense of speed is the instantaneous response of the sound, the portrayal of the instantaneous explosive force.

The sound with a fast sense of speed will appear real, and the slower speed will be unreal. The real sense of speed is like the ice cream that has just been squeezed out, although it is soft but has a clear shape line. The unreal feeling of slowness is like melting ice in the air, so it's easy to make the sound a mess.

Impact

When I first wrote "AV Twenty", I didn't write "Impact", but it was "image". Now I have removed the "image" and replaced it with impact. The reason is that "image strength" does not seem to be important to AV fans. Instead, "impactness" is often mentioned by everyone. The so-called impact is the Punch in English, which is the sound effect of the impact, such as the sound of the fist hit on the body, the sound effect of the car collision, the sound effect of the explosion, the sound effect of the bullet hit on the human body, etc. are all impact performance. The better the impact performance, the faster the speed response and the stronger the strength of the sound system. This feature will make AV fans excited and indispensable in sound effects.

Low frequency control

The main focus of low-frequency control is on the performance of the subwoofer. However, the performance of the low frequency in the film is not only the performance of the subwoofer, the front channel and the center channel are still responsible for the low frequency performance, so I am not called the control of the subwoofer.

The performance of the low-frequency control difference, listening to the ear becomes a rumble of bass, I do not know what the sound of these basses. Applying audio language, that is to say, those low-frequency sounds have no texture, and it is impossible to tell people what is the low frequency. If the low-frequency control is good, not only can we clearly point out the low frequency that is emitted from it, but also feel the strong low-frequency impact, shock or power. At the same time, the ability to low-frequency convergence will be strong. In short, the low-frequency control is good enough, the kind of low-frequency that the AV fans want to hit in the heart, the thrill of the whole body will appear.

Sense of space

No matter where the scene of the film is, we should be able to hear the spatial feeling of that scene in our ears. This is the sense of space. For example, if the scene is in the wild, we must hear the open voice in the wild. Scenes in the concert hall, we must be able to feel the space feel of the concert hall. The scene is on the plane, and we have to feel the sound as if it were on the plane. These are all known as the sense of space.

The appropriateness of the sense of space is related to the sound effects arranged by the sound engineer during the mixing, as well as the speaker placement and processor quality. If the sound recording engineer is not doing enough, other efforts may be in vain. In the same way, if the sound effect sounder is very delicate to make the sense of space, but your speaker is not properly placed, the processor quality is not good enough, it is impossible to give birth to a real sense of space.

Detail performance

The more detailed the sound is arranged, the more detail the sound will be; the higher the quality of the speakers, AV processor or amplifier, the more detail the sound will be heard in your ears. The details of the sound are as if the color is rich, and it sounds more realistic. With less detail in the sound, the overall sound performance will be more dull.

The above is the "Audio Ten Must" of the sound effect, and the next thing to say is the "Video Ten Must" of the image quality. "Video Ten Commandments" includes "Skin Tone", "Color Saturation", "Color Richness", "Screen Sharpness", "Screen Minness", "Object Texture and Gloss", "Resolution", "Dark Level" "The depth of field" and "image stability"

Skin tone performance

Skin color is the same as dialogue, which is easy for ordinary people to judge. Remember, the older generation likes to think of Tint as skin color. In fact, we all know that Tint refers to the type of color. However, because the previous people did not understand the meaning of the SMPTE patch check chart, only know that when Tint is adjusted, the skin color of the face will start to change, so it is customary to describe Tint as skin color.

From the experience of the older generation to Tint's adjustment, we can know that skin color is a simple way for the average person to judge whether the color is correct or not. In fact, skin color is also a manifestation of the color performance. It is important to know that the color of the characters in the film is carefully applied, and the colors it displays are very balanced and meticulous, as well as matte. If these three qualities can be presented on the actor's face, they must be displayed elsewhere in the picture. On the other hand, if the skin color can not reach a balanced and delicate pink, the color performance of other parts must not be better.

Therefore, our first and most important requirement for image performance is skin color. Perhaps, we like to say that we want a natural skin color. In fact, the natural skin color can not be seen under the sharp lens, we should say the skin color we want to see in the lens. In order to get a good skin tone performance, it is natural to adjust from the color value Tint or Hue key, and then continue to adjust the color density value Color after adjustment. If your imager provides further adjustments (such as red and blue to adjust brightness and contrast, or RGB Gamma correction), it will have a more detailed performance. Of course, these adjustments are more difficult and not something that ordinary people can do.

Color saturation

What is the saturation of color? It is the degree of color shading. We often say that the color of the LCD projector is not saturated enough, and the color of the three-gun projector is saturated, which is also a comparative example to understand the color saturation. The more saturated the color, the higher the purity of the color, and the color is not saturated enough as if the color was diluted.

A moderately-performing color saturation itself contains a very fascinating color lustre that does not show a fascinating luster when the color saturation is too dark or too light. If the color saturation of the picture is not enough, the picture will appear lighter colors, even doped with light that should not be there (like the black representation of LCD projectors). What is the appropriate color saturation? Although everyone has different degrees of preference for color, it is best to use the SMPTE patch checker to adjust (adjust the Color button). After correct adjustment of the Color key, plus the correct brightness and contrast key adjustments, these three together add the correct color saturation.

Color richness

A computer monitor can be 256 colors, or it can be a million colors, or it can be a million colors. Similarly, the colors presented on the screen should be as rich as possible. The rich colors make people feel that the images are more natural, more real and softer, and the colors are not rich enough to make the image tone hard and poor. The resolution of the CD is increased from 16Bit to 24Bit, and the level representing the sound is divided more finely. All the more detailed layers are connected closer to the analog waveforms that were not digitized. The video signal of a general DVD player has evolved from 8Bit to the current 10Bit, which also represents the evolution of the richness of the color class.

Can the richness of the color of the picture be improved by the adjustment of the user? If the original adjustment is not correct, it can of course be more abundantly expressed by correct adjustment. However, most of it will still be bound by the limit. Poor software itself, poor DVD turntables, or poor imager effects can affect color richness.

Sharpness

Under the same imager, we often find that some videos are a little blurry, while others are sharp and clear. In theory, the picture is a bit fuzzy, it should not be a phenomenon, but we can easily see such a film missing from the big screen above 100吋. It's as if we used 135 negatives to enlarge to 16 full versions, and the objects on the photos have already been blurred. If we use a 4X5 negative, the objects in the photo will still maintain the sharpness of the lines.

In general, TV pictures are less likely to feel the difference in sharpness of the picture because of its limited picture size. And the projection of the big screen is more than 100 辄, and the sharpness of the picture is easy to distinguish. Some readers may think that adjusting the Sharpness key can improve the blurring problem. In fact, Sharpness mainly compensates for the loss when converting between RGB and NTSC. Adding a little bit is OK, adding more is equal to adding noise to the picture, but it has a negative impact.

Perhaps the reader will doubt that the quality of the film produced by professional technicians will not be sharp enough. Usually, most of the original negatives will not be problematic, and the problems occur in various conversion processes. If during the conversion process, the staff can watch the screen with more than 100 miles, they will find the problem. However, most of the studios still use 19-inch standard monitors (the 19-inch image quality limit was adopted when NTSC developed specifications). Of course, such a small screen cannot be found to be blurred when the system is changed. .

In addition, the CRT's scan line and the LCD projector's grid have become a killer that hinders sharpness. It can be said that the CRT under the large projection is equal to the view through the blinds, and the LCD projector is the view through the screen window. Only the film (Film) is like opening the window to see the scenery outside the window.

Here I would like to remind users who use large screen projections, whether using a 7-tube 8-inch tube or a 9-tube three-gun projector. If the multiplier is not added, the picture quality of the best picture quality is only about 80-120. It’s just around the corner. With the current NTSC system, the picture quality will begin to deteriorate beyond this limit, especially when the sharpness of the picture above 120 更 will be deteriorated. The larger the CRT pipe diameter is, there is no absolute relationship with the intensity of the light output, so even a 9-inch pipe is not suitable for a large screen size. However, the larger the diameter, the more detail the picture will appear. Under the same projection size, the large-diameter projector will naturally perform better.

Picture detail

The detail of the picture is the same as the sharpness of the picture on the previous item. It is easy to distinguish it under the large screen. Under the small size screen, if you don't look carefully, you can't tell the difference. Usually, in order to make the picture look brighter, we will increase the brightness and contrast values. The problem is that when you increase the contrast value (Contrast), the resolution may be reduced and the image quality will become coarser and thicker. Also, as you increase the sharpness value, the picture may become rougher and rougher because you have added a lot of noise that you shouldn't have.

An excellent display, the intersection value that is high enough to start degrading the resolution will be higher than the poor display. In other words, an excellent display can obtain a higher contrast value without degrading the resolution. In this way, both the better contrast and the original resolution can be achieved, and the meticulousness of the picture will naturally be higher.

Resolution

The term resolution seems to be understood by everyone, but there are actually many misunderstandings. Simply put, it is how much detail we can see on the display. In terms of printing, how many color points per square inch (dpi) is usually used to evaluate the resolution of the print. In the case of the NTSC system, the number of horizontal scan lines (for example, the difference of 480i or 720p) and the horizontal resolution (for example, 1280 in 1280×720) are one of the criteria for measuring the resolution.

Usually, the display specifications tell us that the resolution is only an ideal value. In fact, what our eyes see is far below those indicated on the specifications. For example, some TVs have a horizontal resolution of 600 TV lines. The problem is that the horizontal resolution of DVD software is only about 480 lines (or up to 540 lines), and the LD is only 425 lines. If the resolution of these specifications is re-deducted Some of the internal loss of the display, when finally in our eyes, the resolution will be lower than the equipment specifications. Therefore, when evaluating the resolution, it is like evaluating the sound, and relying on what you see, rather than just trusting the numbers.

Dark level

What is the dark level? Simply put, in the darkness, you can see what is inside. Whether it is a traditional direct-view TV or a large screen projection, the dark level is a difficult performance. However, the dark level is a very important performance. Think about it, as long as you encounter a dark scene, the picture shows a black, how cool the picture quality.

We all know that the brightness brightness adjustment is the starting point for determining black, and the Contrast adjustment is the highest peak value of white. These two adjustments are equal to the dynamic range between the black and white of the display. How to set the dynamic range of black and white in the most ideal position, and the maximum without distortion, this directly affects the performance of the dark level. Adjusting the brightness value and the contrast value are directly related to the performance of the dark level. You must use the help of the test piece to make the correct settings, otherwise it is difficult to get the correct dark level performance.

Object texture and luster

The texture and luster of the object is a comprehensive indicator of the various properties of the display. The resolution is not high enough, the color performance is not correct, the edges of the object are jagged white, the contrast between black and white is not good, the brightness of the picture is not enough, etc., which will affect the realism of the object texture and luster. In particular, some small objects such as pens, knives, and small meshes are more difficult to express the texture, not to mention the luster.

If the texture and luster of the object can behave very realistically, it means that the above six indicators (except skin color) perform well. Object texture and gloss are not good. As far as CRT projectors are concerned, the lack of light output is one of the main reasons. The setting of brightness value and contrast value is not the correct reason. In the case of LCD or DLP, D-ILA projectors, the reason for the poor texture and gloss of the object is not that the light output is not enough (their light output is usually high), but the image fill rate (or aperture ratio) is not high enough. To. In addition, the advantages and disadvantages of the internal image adjustment circuit of the projector are also related.

Depth of field

We sometimes hear people say: This TV looks like a depth of field, and that one looks flat. The same is TV, how can there be such a difference? Our eyes should distinguish the sense of distance in a plane, relying on the size ratio of the object and the level of light, in other words, the perspective of the object and the light.

From the comparison between HDTV and NTSC TV, we found that the depth of field of HDTV is particularly good. In-depth observation, we will also find that the light level of the HDTV and the object texture and luster are particularly good, coupled with low picture noise and high stability, so that the picture produces a clear depth of field.

In the NTSC TV, the landscape with a still picture is more likely to show a sense of depth of field. When the object moves on the screen, since it will be interlaced with the horizontal scanning line, the black scanning line will appear in the vision, and the depth of the picture will be destroyed.

Picture stability

If you are close to a TV screen or a large projection screen, you will find that the picture is always noisy/flashing/jittering or even turbulent. From a certain point of view, these problems in the NTSC TV system are like the distortion in the sound system. It is composed of interlaced scanning, noise, unsynchronized picture and vision before and after the image, and various distortions. However, the distortion of the sound system is not necessarily heard. The distortion of the TV system picture can be clearly seen with the naked eye. In particular, the sense of turbulence that appears when a plasma display is at a certain IRE brightness is quite annoying. If the CRT projector adjusts the contrast value too high, it will also find that the picture is full of turmoil.

If you don't quite understand what is wrong with flashing/jittering, please compare it with your own active LCD panel computer and you will understand the importance of picture stability. Imagine how tired your eyes would be if your computer display was as flickering/jittering as a normal TV.

Some people may say: It doesn't matter, I can't feel the noise and restlessness of the picture as long as I am far away. That's right, you can't see the noise and flicker and jitter of the picture at this time, but you can't see the fine details of the flicker/jitter at the same time. In other words, you have lost a lot of detail when you feel the illusion of picture stability.

The stability of the picture is not only affected by the display itself, but also the tape-over program of the DVD when converting the movie signal to video. If the production is not good, the picture noise will increase, it looks really sad.

Important home theater noun explanations:

WaveLength wavelength

Since we have the frequency of sound waves, how do we know how long the length of this particular frequency (that is, the wavelength) is? At this time, we must of course know how far the sound wave can be transmitted by the fluctuations per second. This is the speed of sound fluctuations (sonic speed). Here again remind you of this important concept: the sound wave is not a one-way run from the sound point, to see how far you can run, and get the speed of sound. The sound waves are not so stupid. Instead of running 100 meters on their own, they find a lot of companions, arranged like dominoes (air molecules). When the sound waves start to vibrate, they push the second air molecules down. The second one The air molecules pushed down the third air molecule, so that all the dominoes were quickly pushed down in a second. If the domino can push down 344 meters in one second, it means that the speed at which the dominoes are pushed down is the same as the speed of the sound wave "fluctuation". Usually, the speed of sound waves is in air, at a normal temperature of 20 ° C, and the speed per second is 344 meters. For the convenience of calculation, many audio fans will be 340 meters. Since there is a frequency and a wave speed of sound waves, the formula of the wavelength appears. Wavelength = speed of sound ÷ frequency. This formula is most commonly used by audio fans. If we want to calculate the wavelength of 20Hz, as long as 20Hz as a component mother, 344 meters as a component, we can find a wavelength of 20Hz is about 17 meters. Similarly, if we want to know the wavelength of 10 kHz, we can also use 10,000 Hz as the denominator and 344 metrics as the molecule, and we can find the wavelength of 10,000 Hz to be 3.44 cm. Usually, the so-called wavelength refers to "full wavelength", which is a complete reciprocating fluctuation. If the fluctuation has only one "to" and not "re-", then we will call it a half-wavelength. For example, the full wavelength of the previous 20 Hz is 17 meters, then the half wavelength is 8.5 meters. Does wavelength have anything to do with audio fans? Of course! It is used in the application of sound wave diffraction, diffusion, reflection, and many speaker designs.

In addition, the wavelength is also related to how much frequency a closed space can regenerate. What is the relationship? We all know how low the frequency of the instrument can be related to its duct air resonance wavelength (wind instrument) or the length of the string vibration (stringed instrument) (also related to the thickness of the pipe or string, not here) talk). The longer the pipe or string, the lower the frequency at which it can be regenerated; conversely, the shorter the pipe or string, the higher the frequency at which it can be regenerated. This is also the reason why the violin or guitar finger presses in the direction of the piano, the higher the pitch, because the length of the chord that can vibrate is shorter. Similarly, we can also think of a closed space as a sounding instrument, the difference is that this room is not played by you, but by the speaker. When the horn emits a sound, like the instrument, the lowest frequency that it allows us to hear is related to the "longest side" length of the room. In fact, the length of the longest side is the wavelength of the lowest reproduction frequency. What is the longest side? In a room, it refers to the diagonal of the third dimension. How long is the diagonal? It can be calculated using the Pythagorean theorem of a right triangle. However, you don't have to calculate it, as long as it is estimated by the length of the room. Here, if we assume that the length of the longest side of a closed room is 10 meters, then the lowest frequency that can be regenerated in this closed room is theoretically only 34.4 Hz (sound speed as a numerator, room length as a denominator).不过，由于半波长(一个往或一个复的波动)的声波波动已经可以让我们人耳听到声音，所以理论上10公尺长的密闭空间内，我们可以听到17Hz的频率。看到这里，您不妨把自己音响空间内的最长边找出来，计算一下这个空间能够发出的最低频率是多少?以后您到别的音响迷家里踢馆时，如果他吹嘘自己不到5坪大的空间内能够听到20Hz的极低频，您就可以告诉他：这是不可能的!

THXUltra/THXSelect/THXUltra2

这三种THX认证都是继THX认证之后推出的，可以这么说：THXUltra是THX的升级版，而THXSelect又是THXUltra的小空间版。THXUltra着眼于垂直聚焦的要求，以及更好的超低音表现能力。而THXSelect则着眼于让体积小的喇叭也能够得到大喇叭的音效，尤其着眼于要比THXUltra更佳的低频向下延伸能力。也因为如此，THXSelect标志只会出现在AV收音扩大机以及喇叭上，因为它主要针对室内容积在2,000平方英尺的空间。而在讯源、前级与后级上就不会有THXSelect的认证商标。

总之，在机器内部的处理程序，不管THXUltra或THXSelect都与THX一样，但是在各项AV器材以及空间的认证上，THXUltra比THX更严格些，而THXSelect则针对2,000平方英尺以内的空间另做要求。目前，最新的THX认证已经发展到THXUltra2，所谓THXUltra2认证是在2001年9月12日宣布推出的，它最主要的重点是对于8声道的回放处理与认证，无论是电影音效或多声道音乐都适用。此外，机内的视讯频宽要达到HDTV水平，也要能够接受循序扫描视讯，其它大体上与THXUltra的要求相同。

THX是什么

是由Lucasfilm公司从1985年起所发展出来的一种电影音效处理系统。它的起因是GeorgeLucas本人发现为电影院播放而录制的电影音效，其实并不适合在家庭里播放。因为电影院的空间大，所以往往在混音时，会把高频段强调。而在家庭里看电影时，反而就会觉得高频量感太多了。为此，THX的工程师们发展出精确的处理过程，能够把电影混音师真正想要让观众听到的声音在家庭里精确再生。

THX处理系统分为三部分，第一部分为Re-Equalization再等化。第二部分为TimbreMatching音色匹配。第三部分为AdaptiveDecorrelation解关连适应。前面说过，因为电影音效是为大空间的电影院以及专业音响设备而做的，因此在家里播放起来，高低频的平衡性会相反。为此，就必须先经过再等化的过程，让电影音效的高频段与低频段在家庭小空间播放时取得适当的声音平衡性。这就是，再等化的目的。

什么是音色匹配?在电影院中，环绕声道并不是二支环绕喇叭而已，而是喇叭「数组」，意思就是说有很多支的环绕喇叭。这样的声音当然与家里只使用二支或三支甚至四支环绕喇叭有很大的不同。假若不把电影院音效先经过处理，家里环绕声道所发出来的音色与主声道所发出来的音色会有相当的差距。为此，就必须把电影院音效(其实就是已经录制在DVD里的音效)里的环绕声道先经过一道滤波处理，让环绕声道的音色能够与主声道的音色相搭配。这就是音色匹配。

最后一个问题就是环绕音效包围感的问题。当我们在电影院时，环绕喇叭很多，所以能够得到很好的身历其境包围感(Enveloping)。但是，在家里时我们通常只有二支环绕喇叭，这时的环绕包围感与电影院的很多支环绕喇叭所形成的包围感就有落差。此外，在家里观影时，最佳的环绕包围感永远都是在最中央的位置，只要离开中央位置，环绕包围感就会降低。为了得到如电影院般身历其境的环绕包围感;也为了扩大最佳环绕包围感的区域，THX让左右环绕声道的其中之一改变其相位与时间延迟，故意让二个环绕声道相互产生相位差与时间延迟，这样就能够只用二支环绕喇叭得到如电影院般最佳的身历其境环绕包围感。此外，即使您不是坐在中央，也能享受到比未处理前更好的环绕包围感，这就是解关连适应。

除了以上三大功能之外，THX还可以帮您做BassManagement低频管理、BassPeakLevelManager低频音量峰值管理、LoudspeakerPositionTimeSynchoronization喇叭定位时间同步等工作，这在THX选单里就可以看到。要提醒您的是，上面三大功能是接续在DD或DTS解碼之后的再处理，它是自动生效的。而此处的三小功能则是在选单中选择，例如THX的超低音上限就只有80Hz，而非120Hz。总之，只要您点选选单中的THX设定，则所有设定参数都会依照THX要求设定好。

看到这里，您已经知道原来THX处理并不只是一个认证商标放在机器面板上而已，它真的有在工作，可以把声音的平衡性处理得更好，让主声道与环绕声道的音色匹配，更能够让二支环绕声道喇叭产生如电影院般的身历其境环绕包围感。现在，您应该不会再认为THX没什么用处了吧!事实上如果想把THX标志放在机器面板上，并不是付钱买商标那么简单，厂商还必须把机器送到THX来测试，必须各项性能都符合THX要求才能获得认证。所以，当您买了面板上有THX商标的机器时，就代表了拥有双重保障：制造厂商与THX。

对了，要提醒您的是，THX处理程序只对电影院音效有效，其它音乐软件或为电视而混音的电影音效并不会触动THX处理程序，因为这些都不是为电影院大空间所炮制的音效。

空间微调。当我们把空间主体以处理空间的方式大体处理完毕之后，有时候声音就已经很好听了，但更多的时候是还必须经过微调。要微调空间，必须先对二样东西有初步了解，第一个就是反射音，第二个就是残响时间。其实，反射音与残响时间是孪生兄弟。当喇叭发声声音时，最先到达耳朵的是直接音，直接音左右了我们对于乐器发声点的位置判断，以及各种乐器人声音质音色的判断。当直接音传入耳朵之后，陆续会有各个方向的「第一次反射音」传入耳朵。到底从那里来的第一次反射音会继直接音之后最快进入耳朵?通常是从地板传来的第一次反射音，接着可能会是从二侧墙传来的第一次反射音，再来可能是从天花板传来的第一次反射音，最后才是喇叭后墙以及聆听位置后墙传来的反射音。第一次反射音传入耳朵的先后是由声波从反射到进入耳朵的旅行长度来决定的，假若我们的喇叭距离后墙很远，而您的聆听位置又是贴墙坐着，那么从聆听位置后墙反射到耳朵的声波就会快过从喇叭后墙反射过来的声波。

声波并不是只反射一次而已，它会依循着一样的反射角度(定向反射)或不同的角度(扩散反射)不断产生第二次反射音、第三次反射音、第四次反射音…等等，一直到反射音完全消失为止。这么多的反射音重迭之后就会形成微妙的声音延长效果，这种效果对于声音的丰富性有很大的帮助。通常，在直接音发出之后30-50ms以内到达人耳的反射音，会与直接音混合，增加了直接音的声音强度，同时也提升了直接音的清晰程度。不过，假若超过这个时间之后声音还是没有停止，那就会开始对声音的清晰程度产生负面影响。所以，在聆听空间中，我们一方面需要反射音，另一方面又需要控制反射音。假若反射音一直持续下去，我们就称之为残响(Reverberant Sound)。残响时间的定义为声音发出之后，能量降到最初的百万分之一(60dB)所需的时间，又称为RT60。

在一般现在的音乐厅中，残响时间大概都以500Hz或1000Hz中心频率2秒为主，少数也有超过2秒者。如果是歌剧院，残响时间则要比2秒更短些，大概都在1-1.5秒之间，好让歌唱的咬字能够听得更清晰。至于教堂，残响时间有的长达8-10秒，所以教堂内适合唱旋律线条很长的诗歌，而不适合唱摇滚乐。残响时间2秒对于一般聆听空间而言当然是太长，比较适合的家居聆乐空间残响时间大概都在0.5秒以内，视不同空间大小而有不同的需求。

到底0.5秒以内是多长?老实说用耳朵是无法判断出来的，必须用仪器测量。不过我们也有土炮估量方式。以我的经验而言，如果进入一间装潢好的空间，讲话感觉有点吃力，那就是残响太短，吸音表面积太多了。反之，假若讲话觉得丰润不吃力，大声讲话也不会听到回音时，就是相当适合听音乐的残响。如果拍手在室内行走，可以清楚听到屋顶角落反射声波回来，那并不一定代表残响太长，而是声波扩散不均匀所致，一定要处理。

当我们在做空间微调时，最重要的工作其实就是处理反射音以及残响时间。不同墙面来的反射音我们必须适当控制，否则就会干扰到直接音的清晰。假若反射音太杂太多，我们听音乐时就会感到声音不够干净澄澈。同样的，当残响时间太长时，我们所听到的声音虽然有可能会比较甜美，但在清晰度上也会大受影响，尤其是低频段。还记得前面说过，反射音与残响其实就是孪生兄弟，如果把反射音处理得当，残响时间也会随之改变。当然我们不会用仪器去测试，唯一的「仪器」就是我们的耳朵。因此，空间微调的成败就受到微调者「经验」的左右。

在做空间微调时，首先您要选择几种音乐讯源，一种是巴洛克音乐，一种是大型管弦乐、一种是摇滚乐，这三种音乐讯源都要反复聆听，一直调到三种音乐都能够有相当不错的表现才行。为什么要选这三种音乐呢?因为巴洛克音乐注重的是长线条的优雅，而且本身乐团规模不大，可以让我们当作残响时间的最长上限。如果巴洛克音乐听起来就觉得尾巴太长，那室内的残响时间肯定就会太长。假若巴洛克音乐听起来还觉得太干，肯定就是室内残响时间太短。一定要取这二者之间的感觉才对。

大型管弦乐由于乐器种类多，规模大，音量强，能够让我们判断来自各墙面反射音的控制状况。假若大型管弦乐听起来很乱，那就代表各墙面的反射音(尤其是第一次反射音)太多，已经干扰到直接音的清晰。假若大型管弦乐听起来清晰而不乱，低频段的乐器音阶也可明确的听出来，那就表示各墙面的声波反射状况控制得相当好。

摇滚乐注重的是冲击性与快速反应，这可以让我们作为残响时间的最短下限。假若我们听摇滚乐觉得速度反应快，控制力佳，冲击性强，而这一切又都不乱，那就表示这里就是残响时间的最短下限，不能比这个更短了。

当我们用这三种音乐反复聆听之后，如果发现残响时间太长，则必须使用各类能够吸收反射音的调声产品来调节残响时间。市面上有许多这类的产品，它们或多或少都有效，重要的是您要知道怎么去使用它。最简单的原则就是把这些吸音的调声产品放在墙面第一次反射音的区域上。

什么叫做第一次反射音的区域?在此我教您如何找出各墙面的第一次反射音区域。请去拿二支蜡烛，将它们点燃，以架子架起来，放在喇叭的摆放位置上，光源的位置就在喇叭高低的中段上，此时当然事先要把喇叭移开。这样做的目的是要让蜡烛的光源模拟声波，因为当我们把声波暂时当成直线来看时，就与光源的辐射差不多了。

接下来，要请一位朋友拿一面镜子，请他拿着镜子在各墙面游走，镜子的高度就是光源的高度。此时您自己坐在聆听位置上看着镜子。当您可以在镜子里看到光源时，就表示那里就是第一次反射音的反射区。请注意，反射区是一个区域，不是一个点而已。还有，不是只有一支喇叭会从墙面上反射声波，而是二支喇叭都会从墙面反射声波。用这样的方式来找出各墙面的第一次反射区很精确，唯一比较困难的就是天花板的第一次反射区。到底要怎么让镜子能够在天花板上游走?如果您没有更聪明的方法，那还是用梯子吧!

找到各墙面的第一次反射区、并且标示出来之后，您就可以开始用各种吸音调声产品来吸收第一次反射音。假若您不想花钱，也可以自己买吸音材料来使用，或者干脆用厚毛巾。不过此时可能就要花点心思，才会让这个空间不至于太难看。

空间微调是音响迷在空间上下功夫的最后一个步骤，按理说如果把空间长宽高比例、空间处理等做好，再加上空间微调，聆听空间的声学特性应该能够达到相当理想的境地了。接下来还能做的就是对家庭影院音响器材的微调(EquipmentTuning)了。

文中配图详见word文档：《标准THX家庭影院装修过程》(多图详解)。

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