Home theater audio debugging full analysis of speaker wiring debugging

Before we introduced "Home Theater Speaker Installation and Audio Tuning Precautions", home theater audio adjustment is a long learning process, which is more important than buying audio. The cheaper sound is also good for the baby. If the expensive audio is not well adjusted or not adjusted, it is also a waste of money. First download the "Audio Technology and Music Appreciation Manual" PDF version of the online learning, look at the following.

Home theater audio debugging full analysis of speaker wiring debugging

table of Contents:

The first chapter of the home theater audio debugging full analysis of the speaker wiring debugging

The second chapter of the home theater audio debugging full analysis of the subwoofer settings

Chapter III Use of Sound Analyzer for Full Analysis of Home Theater Audio Commissioning

The fourth chapter of the home theater audio debugging full analysis of the power amplifier configuration

The fifth chapter of the home theater audio debugging full analysis of the impact of the power supply

The sixth chapter of the home theater audio debugging full analysis of the two-line crossover

The seventh chapter of the home theater audio debugging full analysis of the top ten lies in the audio industry

Chapter 1 begins wiring debugging

First press the 5.1 channel arrangement, followed by the 6.1-7.1 channel. Use the Tajima Laser Rangefinder to measure the distance of each speaker. Set the distance parameter of each speaker. The gun is on the same horizontal line as the main speaker, and the phase is temporarily set to 0°. The subwoofer switch cutoff band is 120HZ. Start wiring, 4 pillars under the main box LE+, LE- (woofer), HE+, HE- (high-midrange unit), two pairs of copper to the short connection, through the study of "Audio Technology and Music Appreciation Manual" The woofer is better. Remove the original solder oxidized old head and connect with a new one.

During the commissioning phase, according to the original reference frequency range of the DIV6.3HT speaker

Front main box: 38HZ-20KHZ;

Center: 60HZ-20KHZ;

Surround: 60HZ-20KHZ;

Subwoofer: 25HZ-200HZ.


Settings: Front "Small", center "Small", surround "Small". Subwoofer Mode: "LEF".

Settings: Crossover Frequency main box: "40HZ", center: "60HZ", surround: "60HZ,"

Settings: Audio Settings - 2-channel Straight In / Stereo - Crossover: "80HZ", the value is too high and low frequency is turbid, the value is too low and the bass is insufficient.

According to the following: "Forever topic: On the crossover setting of the AV amplifier and the cutoff frequency setting of the subwoofer"

First of all, before understanding the settings of these two aspects, we must understand why the AV amplifier / subwoofer has such a design? As long as they understand their original design, all problems are naturally solved! So why is this design? From the technology of Dolby (AC-3) and DTS.

1) Dolby Digital surround sound

The Dolby Digital Surround System (AC-3) is a fully digital audio pressure coding system newly developed by Dolby Laboratories. There are 6 (5.1) fully independent sound channels: 3 front left, center, right channels and rear left and right surround channels and subwoofer channels.

The first five are full-range (20HZ~20KHZ), and the subwoofer channel has a frequency range of only 20HZ~120HZ, so it is called ".1" channel. The volume of the subwoofer is required to be 10 dB larger than the other channels, which has a more powerful low effect.

Dolby Digital AC-3 is a coding system multi-channel surround sound developed based on the feeling. The frequency of each sound is divided into a number of narrow frequency bands according to the auditory characteristics of the human ear. In the encoding process, the sound psychology is analyzed according to the principle of sound psychology, the effective audio is retained, and the excess signal and various noise frequencies are deleted. The reproduced sound is purer, all the signals of the six channels are independently digitized, and the separation of each channel is as high as 90db, which is a prominent advantage of Dolby Digital. The Dolby Digital Surround System is also approved by Dolby Laboratories.

2) Digital Cinema System (DTS)

DTS is the abbreviation of Digital Theater System, which is a digital cinema system. It is a digital surround sound system jointly launched by DTS and Universal Studios. The DTS system is similar to Dolby Digital. It is also a multi-channel compression coding technology that combines 6 or more digital soundtracks with the time specified by SMPTE (Film and Television Engineering Association). The code is synchronized and directly recorded in a movie copy or other software. The digital compression technology of the audio signal is actually a re-encoding process of the linear pulse code modulated digital signal. The DTS can perform 20-bit original sound quality on 6 channels. The audio signal is encoded and decoded. DTS uses CAC (Coherent Acoustic Coding) structure compression method different from Dolby Digital compression mode, the typical compression ratio is 3:1, only one quarter of Dolby Digital, the original signal loss is less, can be retained The original fine signal in the sound field, DTS 96KHZ sampling frequency is double that of Dolby Digital 48KHZ, and easily increase the data transmission rate to 1411Kbps, which is three times higher than Dolby Digital's 448 Kbps, so its reproduction The sound field is ideal in terms of continuity, breadth and hierarchy.

Dolby AC-3 / DTS main performance characteristics table

Category Dolby AC-3 DTS

Number of channels on the software 5.1 5.1

Number of channels after decoding 5.1 5.1

Channel composition LCR SL SR SW LCR SL SR SW

Round channel number two channel two channel

Left middle right speaker frequency response 20Hz-20KHz 20Hz-20KHz

Surround sound box frequency response 20Hz-20KHz 80Hz-20KHz

Subwoofer speaker frequency response 20HZ-120HZ 20HZ-80HZ

Dynamic range 105db 138db

Inter-channel resolution 105db >105db

Output signal to noise ratio 115db >115db

Signal recording digital mode digital mode

Everyone pays attention to the keywords: the frequency response range of each channel

Dolby AC-3

LCR SL SR SW The five channels are all 20Hz-20KHz in full range!

The frequency range of the subwoofer channel is 20HZ-120HZ!

Stage summary: According to the technical specifications of Dolby AC-3, the most ideal configuration in extreme conditions is: 5 main/middle/loop speakers capable of restoring 20HZ-20KHZ. A subwoofer capable of restoring 20HZ-120HZ.

The question arises: Is there such a main/medium/loop speaker in the world? Even if it is, its price + volume can be accepted by several people? Hahahahaha.............So Said: everything must be started from reality!

Ok, now let's pair with the most common 5.1 AV system.

Main box landing - frequency response range: 40HZ-20KHZ

Center - Frequency response range: 80HZ-20KHZ

Surround-frequency response range: 80HZ-20KHZ

Active ultra-low speaker - frequency response range: 25HZ-200HZ

Ordinary with decoding AV amplifier (without crossover adjustment function)

According to the technical specifications of Dolby AC-3, what is the problem with this system? A: The frequency band is lost!

The frequency band of LR main channel 20HZ-40HZ is lost!

The frequency band of the center/surround 20HZ-80HZ is lost!

The frequency band of the subwoofer 20HZ-25HZ is lost!

It can be seen that the subwoofer loses the least detail, and the main/medium/ring loses so much detail that you can bear it???

At this time, the little devil jumped out and said: "The world is the smartest of us, so we all call us a devil, let's solve it! Add a crossover management to the AV amplifier!" The AV function of the management function was born. It can assign the low frequency signal that can not be restored by the main/middle/ring to the subwoofer to handle it (who makes you have this ability and the most leisurely)! Hahahaha...

Stage summary: Because most of the speakers can't restore all the low-tone signals of the channel, in order not to lose or minimize the loss, the AV power amplifier's crossover management function is also brought into play, and the human ear is also utilized. The low-frequency signal below 100HZ has no sense of direction. It is actually a compromise that is forced to helplessly. It is also a kind of deceptive deception........

Ok, see if everyone understands how to set the system's crossover point?

Add a few notes:

1) The high-end AV amplifier (or the pre-decoding stage) has the independent crossover point setting function of each channel, so that different crossover points of each channel can be set according to different combinations, for example, the 5.1 system as exemplified above. You can set the crossover point of the main box to 40HZ, and the crossover point of the center/surrounding to 80HZ, which is closer to the requirements of Dolby AC-3.

2) Most AV amplifiers have only one uniform crossover point setting, so that in order not to lose the frequency band, only the center/around weakest point (the one with the highest frequency lower limit) is the best setting for the crossover point.

3) About the setting of the speaker size: If the crossover point has been set, if the main box is set to be large, then all the signals of the main channel are all given to the main box, and the subwoofer is not available at all! Unless you The main box can dive deeper than your subwoofer, otherwise the low frequency signal of the main channel will be lost more!

If the main box is set to small, the signal of the main channel above the crossover point is still replayed by the main box, and the low frequency signals below the crossover point are all handed over to the subwoofer for processing. The size of other channels is set. And so on!

4) Most AV power amplifiers have a choice of “BOTH” in the subwoofer setting. In the case where the main box is set to a large size, the sound below the power amplifier crossover point can be simultaneously output from the subwoofer and the main box.

Finally talk about the cutoff frequency setting of the subwoofer:

Most subwoofers have this setting knob on the rear panel. The general cut-off point is adjusted freely from 40HZ-120~200HZ. Which is the right button for this button?-------(Off-topic: Many people think this The cut-off point is set to be slightly higher than the crossover point of the power amplifier. In fact, it is wrong. Why do you say this? Please look down.)

First of all, to figure out what the subwoofer under 5.1 is doing? Reviewing the above, according to the technical specifications of Dolby AC-3, this ".1" should be a completely independent channel! The theoretical frequency of this channel The range is 20HZ-120HZ. But the hateful devil in order to solve the problem of loss of the main/middle/ring band, through the frequency division management of the amplifier, added the low frequency signal of other channels (please note that it is added, not independent) The subwoofer channel is also brought in for mixing.) Therefore, the subwoofer is a heart-to-heart tube, doing both the work that you should do, and helping others to work! (Oh.. no way, the upper finger is sent) Then, what is it called "cutoff point"? Simply put, this "point" determines the working frequency range of the subwoofer. It doesn't matter if it is above the point.

So how much is this "point" set up? A: 120HZ or a little higher!!!


1) Technical specifications of Dolby AC-3/DTS, the frequency response range of the subwoofer channel is 20HZ-120HZ, and the production limit is 120HZ!

2) The lower limit of the low frequency of most speakers will be below 120HZ, which means that the crossover point of the power amplifier is rarely necessary to be set above 120HZ!

Add a point: If you broadcast DTS, then the cutoff point can also be set at 80HZ (below the value of the power amplifier's crossover point), because the DTS ultra low channel frequency response range is 20HZ--80HZ, in short, it is not lost The principle is the principle!

However, switching the track once is going to the back of the subwoofer's buttocks, it seems to be troublesome, so it is still set at 120HZ! The upper limit of the frequency of the overweight subwoofer is set in the bass frequency range. Reserve 10Hz ~ 15Hz space.


I found that there is a Column Level offset setting in AudioAdjust: 0dB for watching movies and 10-15dB for listening to music. When set to 10dB, the music effect is greatly improved.

No sound pressure meter is temporarily measured by the mobile phone, and the channel level value of each speaker is set. The method is as follows:

Use the Android system phone, after the computer is downloaded, install the Tricorder5.12 address on the phone http:// After the installation, the “ACO” item is the sound pressure measurement. In addition to the subwoofer, the channel level is changed and the values ​​of the individual speakers are equal.

Next, replace the original main box crystal line, use the professional sound pressure meter to measure the sound pressure of each horn, and use the audition disc "Emperor", "Devil Tremolo", "Home Theater Technology" correction.

The influence of the placement and placement of the speakers on the sound

1. Direct-type full-range speaker tries to avoid the interface reflection direct-type speaker is the speaker that directly radiates sound directly. In theory, it is a kind of speaker directly coupled with air. In appearance, it is a kind of speaker speaker. Speakers that are directly outwardly set (such as the TAS DP series full-range box, TANBO TX series full-range box, etc.). This kind of speaker mainly relies on the radiation characteristics of sound waves, so that the speaker directly sends sound energy to the space. Under normal circumstances, the direct-radiation speaker's bass radiation angle is larger than the high-pitched radiation angle. If the speaker is placed directly on the ground, the bass is reflected on the ground and transmitted to the listener. At this time, due to the direct transmission from the speaker. The distance that the sound has traveled is shorter than the distance that the reflected sound has traveled. The direct sound of the speaker's bass reaches the human ear in advance, and the reflected sound then reaches the human ear. The phenomenon of the bass “first come and then come” will appear, resulting in a bass ghost.

As we all know, the amount of bass components has a great influence on the clarity and intelligibility of the sound, and the bass itself has a sense of turbidity. If the bass is ghosted, it will make the sound sound more turbid. Direct-type speakers are best not placed directly on the ground, or located close to the corner of the wall, otherwise the bass heard in the listening area will be aggravated, and there is a sense of ambiguity. If the floor of the room is made of a hard, smooth material that strongly reflects the sound, then the bass turbidity will become more serious. In practice, it may be found that in a low-distance room, a direct sound box (especially a full-range direct-type speaker) is used for playback, and the bass sounds turbid often, and the bass is turbid. The phenomenon is impossible to use the equalizer to attenuate the bass component in the sound. There is no bass in the sound. The sound of the bass sound is turbid. The main reason is that there are too many reflected sound components of the bass, and there is a serious ghost in the bass. phenomenon. In order to fully reduce the adverse effects of bass reflection, one of the following two measures should be taken when placing a direct-fire speaker:

First, do not place the speaker directly on the ground or in the position close to the corner of the wall. It is best to use a metal frame to raise the speaker height by more than 40cm, and place it at a distance of more than 40cm from the side wall, and the distance from the rear wall is more than 20cm. The interface is far away, so the bass reverberation is significantly reduced.

Second, if the ground in front of the speaker is a strong reflective material (hard and smooth material, such as marble floor), when the speaker is placed directly on the ground, you can also take the sound-absorbing carpet in front of the speaker to absorb the reflected sound of the bass, but the bass is not It may be fully absorbed and there is still a small amount of reflection.

2, the airflow subwoofer can use the ground reflection airflow speaker is the speaker that does not directly radiate the sound of the speaker. According to technical terms, it is a speaker that the speaker diaphragm (tray) is not directly coupled with air. In the field of professional audio, airflow speakers are generally subwoofers. The modern airflow subwoofer uses advanced aerodynamics to achieve a strong airflow change with a large diaphragm vibration that can only be produced by the bass, and this airflow change enhances the bass. The airflow subwoofer not only makes the bass farther due to aerodynamic characteristics, but also makes the bass more pleasing due to its excellent acoustic characteristics. The airflow subwoofer can be easily identified from the outside. It is a speaker with the back of the woofer facing outwards, facing inward (reverse) or not directly visible on the front of the woofer. The most common speaker is currently in the speaker. There are two types of Tibetan subwoofers and speaker reverse-type subwoofers (eg TAS DP-215B, TANBO TX-2180, DEBOS D-180). They mainly rely on the airflow characteristics of sound propagation, continuously send out a group of bass airflows to the space, and use the airflow group to propagate sound waves instead of transmitting sound energy to the air by simple wave radiation characteristics, and the bass can travel farther. Airflow subwoofers are relatively free to place and install, either hanging in the air or directly on the ground. But in general, it is better to put the airflow subwoofer on the ground. This is because the airflow subwoofer uses airflow, so the bass has a certain directivity, even if there is acoustic radiation, but even if there is acoustic radiation, The proportion of acoustic radiation is also small, so the reflected sound content after reaching the reflective interface is also small, and the bass reflection volume is moderate. The subwoofer is placed directly on the ground, which can fully exert the effect of the ground, which is equivalent to extending the ground as a bass horn. Such a large bass horn makes the sound resistance of the lower limit frequency of the speaker more closely match, and the bass sounds thicker and fuller. .

3, the listening area should fully obtain the direct sound of the speaker. The direct sound is from the speaker directly to the listener's voice. Its main feature is pure tone, that is, what kind of sound is emitted by the speaker, almost heard by the listener. What kind of voice is it. The direct sound does not pass through the wall, the ground and the top surface of the room. There is no acoustic defect caused by the reflection of the interior decoration material. It is also not affected by the indoor acoustic environment, so the sound quality is guaranteed and the sound fidelity is guaranteed. high. An important principle in modern room acoustic design is that the listening area makes full use of the direct sound from the speakers and tries to control the reflected sound. As far as a room is concerned, the method of determining whether the listening area can obtain the direct sound from all the speakers is very simple, and the visual method can be used. In the listening area, if the listener can see the whole of all the speakers, and in the area where all the speakers share the cross radiation, the speaker can be heard directly. Under normal circumstances, speaker hanging is the best way to get direct sound in the room, but sometimes due to the low floor space and limited space, hanging speakers may be subject to certain restrictions. If conditions permit, it is best to hang the speaker. hang up. Many speakers have a horn pointing angle of 60 degrees or less. The horizontal direction is large, and the vertical direction is small. If the listening area is not within the horn of the horn, the horn of the horn cannot be obtained, so the speaker is placed horizontally. The tweeter axis should be consistent with the level of the listener's ear. When the speaker is hung, adjust the tilt angle to avoid affecting the high-pitched sound. When the speaker is playing, the closer to the speaker, the greater the proportion of direct sound in the sound, and the smaller the ratio of reflected sound; the farther away from the speaker, the smaller the proportion of direct sound.

4. The speaker is placed symmetrically with the central axis of the room. The requirement for the indoor acoustic environment is that the symmetry of the building must be consistent with the acoustic symmetry of the room. The speaker should be placed at a symmetrical position on the central axis of the room. Only by achieving the consistency of architectural symmetry and acoustic symmetry can an ideal, harmonious and symmetrical sound field be provided for the interior. If the speaker is placed asymmetrically with the room, that is, the two speakers are biased to one side of the room, there are many problems in playback. Although these problems can be compensated by electroacoustic compensation, the most Well, you should try to avoid a series of problems caused by the asymmetry of placement. Some rooms themselves are asymmetric internal structures or decoration structures. The room acoustics are already asymmetrical. The speaker placement can only make the sound field symmetrical as much as possible. Then, what problems will the sound field asymmetry cause? The following analysis: When the effect adds effect to the sound, it will be found that the reverb sound effect of the speaker farther away from the wall is more obvious than that of the speaker closer to the wall, because the sound volume of the front of the speaker farther from the wall is louder. Larger, according to the theory that the larger the reverberation time is, the reverberation is stronger. The space in front of the speaker closer to the wall is smaller, and the reverberation is definitely weaker. An important requirement of the acoustic characteristics of the hall is to create a uniform sound field. That is, the volume of each position in the sound field cannot be too different. If the sound field is not uniform, the consistency of the volume and the tone of the listening area will be deteriorated. When the speaker is placed asymmetrically, it will cause less reflection of the early reflection sound of the speaker facing the larger space, smaller volume, and the effect of the early reflection sound of the speaker facing the smaller space, and the volume is large. The sound field uniformity is destroyed.

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