[Home Theater Network HDAV.com.cn] Before we emphasized the importance of many subwoofers ("Old Snail: Several Frequently Asked Questions for Gunners"), in view of many users asking about subwoofer related issues, Xiaobian finishing Here is a knowledge quiz about home theater, I hope to help you:

First, the role and significance of the subwoofer

The subwoofer is a common name or a short name for everyone. Strictly speaking, it should be: a subwoofer. In terms of audio analysis that is audible to the human ear, it consists of subwoofer, bass, low midrange, midrange, mid-high, high, and super-high.

Simply put, low frequency is the basic framework of sound, medium frequency is the flesh and blood of sound, high frequency is the detailed reflection of sound.

With the development of technology and the development of the economic base, super bass and broadband have entered the audio world. The subwoofer is to strengthen the architecture, and broadband is to make the difference in sound more clear.

This time we specialize in talking about super bass. The audible smell of the subwoofer is limited, but the other senses of the person will feel it. This is the shocking feeling! In terms of the audio and the source of the home theater, the super bass is only in the specific The source of the program exists and needs to be restored. With it, the restoration of the program source can be made more robust. Without it, it gives people a feeling of lack of power and energy. For example, in the cinema or in reality, we can feel the power and energy of the aircraft when it takes off, but if our home theater is not equipped with a subwoofer or the configuration is unreasonable, we can not feel this shock, but also That's it.

In the audio environment, whether it is listening to music or watching movies, subwoofer (broadband) is needed and should be ensured. This 0.1CH as the subwoofer channel in the two major audio reproduction standards of the digital home theater also illustrates its significance and role, which is necessary, but it can also be compromised.

Why compromise?

Because of the reduction of the subwoofer, as a standard planner, of course, it is difficult to popularize because it is costly. Without the aid of other technologies, the bass playback unit should be large-caliber. In addition, driving such a large-caliber unit also requires a high-power amplifier, which will increase the cost of restoring the subwoofer.

Of course, we can also buy subwoofers that are not very expensive in the market. This is actually another kind of compromise. It is technically a pseudo-subwoofer, but from the perspective of commodities and consumer markets, this is also the market. need.

Second, active subwoofer and passive subwoofer

As mentioned earlier, the subwoofer needs to be powered by powerful power, so most subwoofers on the market are built-in amplifiers, that is, the subwoofer's speakers and amplifiers are independently divided and integrated.

If there is no amplifier in the subwoofer, it is a passive subwoofer.

Third, the unit diameter of the subwoofer

Strictly speaking, subwoofers should use large-diameter units and are generally specially designed units. Compared with the actual audition of various subwoofers at home and abroad, the effect of this large-caliber subwoofer is the best.

However, the market needs to be multi-faceted. Under certain conditions, it is impossible to place a subwoofer with a large volume. In addition, some consumers also like small products, so there is a small subwoofer. Such subwoofers are usually acquired by technical means, such as Dr., Yamaha, the former is the technology of the box design, and the latter is the technology of circuit design. But no matter how shocked the subwoofer, but the "fake" is difficult to cover up, please understand the "fake" that I said accurately, do not spread, so as not to cause unnecessary misunderstandings and misunderstandings.

Fourth, the subwoofer's crossover circuit description

With a large number of subwoofers for home theater systems, the current subwoofer design is becoming more and more simplistic, and this simplicity seems reasonable. Strictly speaking, the subwoofer can only restore the subwoofer signal, so in the early subwoofer design, the front end usually also designed a low-pass filter crossover circuit, which is to filter out the signal higher than the subwoofer so that it does not enter. The rear amplifier interferes with the operation of the subwoofer unit.

In the digital home theater audio decoding specification, the output 0.1CH signal itself is already a subwoofer signal, so for newer systems, the presence or absence of a low-pass filter for the subwoofer has no effect on the subwoofer's operation.

For those who try to use the subwoofer in a two-channel music system, since the usual source or amplifier does not have a separate subwoofer output, it is necessary to extract the subwoofer signal based on the existing system, so no In order to achieve versatility, multi-purpose or competitive needs, low-pass filters are designed in the subwoofer, and two extraction methods are designed:

1. Extract from the low-level signal output of the signal source, generally the RCA input port. It is possible to use a pair of signal lines or a signal line link.

2. The high-level signal is extracted from the left and right speakers. Generally, the same terminal as the speaker terminal on the power amplifier is used. Same as above, the effect is basically the same with two pairs of thin speaker wires or one speaker cable.

Fifth, the setting of the cutoff frequency

The critical point of the low-pass filter mentioned above is the cutoff frequency of the subwoofer. In order to increase the adaptability of the subwoofer, the cutoff frequency of many subwoofers is adjustable.

This cutoff frequency setting is an important debugging environment for playing the subwoofer. It is used to debug the frequency connection between the subwoofer and the speaker. The connection is good, the system performance is perfect, the connection is not good, and it is not the loss of some signals or the destruction of the signal. It is true.

Generally speaking, for bookshelf boxes and small-caliber speakers, the cutoff frequency is higher. For floor-standing speakers, the setting is lower. It is usually necessary to look at the low frequency reduction limit of the speaker.

For example, the lower limit of the low frequency of a speaker is 60Hz, then the cutoff frequency of the subwoofer is set at 60-80Hz. It is reasonable. If it is too high, the bass of the 60Hz part will be excessive. If it is too low, the energy of the 60Hz signal will be lost.

For digital home theater amplifiers, the amplifier itself has a bass management setting that combines the speaker size settings to debug the subwoofer's cutoff frequency setting.

Six: phase (English phase)

Most subwoofers are designed with phase adjustment switches, and the phase adjustment of the advanced subwoofer is continuous.

Phase adjustment is simple, positive or negative. The correct setting should be that the subwoofer sound is more powerful and shocking. If the sound becomes illusory after the subwoofer, you should immediately change the phase switch.

Seven, the connection

For home theater systems, the subwoofer signal is recommended to be input with a low level signal. Usually faced with two choices, one is the multi-channel output from the disc player, and the other is the subwoofer output from the AV amplifier. Unless the amplifier has no subwoofer output terminal, we recommend that the connection be taken from the AV amplifier, so that The subwoofer volume is controlled synchronously by the AV amplifier. If taken from the player, when the system volume changes, you need to adjust the volume of the subwoofer at the same time. This connection, usually in the stereo mode subwoofer is unable to obtain the signal, so there is not much help or improvement for the system, this needs attention.

For attempting to input a full-band signal from a stereo signal into the subwoofer, first make sure that your subwoofer has a low-pass design, otherwise the gun will not work. In this case, the super bass of any program can be enhanced.

Eight, position

Strictly speaking, the subwoofer is lack of directionality, so it can be placed anywhere in the listening room, but considering the huge influence of the environment on the sound transmission, in practice we still strongly find that the pendulum of the subwoofer is moved. The effect of the reduction on the subwoofer is relatively large. When conditions permit, we still recommend that the user adjust the position of the subwoofer to get the best results.

Last but not least, the subwoofer is not always present in the source, so don't misunderstand it while listening or debugging. Because of the habit, in the debugging, people inevitably use the ear to listen to the subwoofer. Does it work or is it shocking? In fact, it is not necessary to use the body to feel it. In order to facilitate debugging, special subwoofer signals are usually also provided in the test discs on the market.

More fresh and fun home theater information, please pay attention to home theater network (WeChat: cnhifi) http://, the country's most influential home theater audio player interactive media website.

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