How to use a home theater subwoofer?

                              How to use a home theater subwoofer?

1. The function and significance of the subwoofer (the soul of the home theater!)

Subwoofer is a common name or abbreviation for everyone. Strictly speaking, it should be: subwoofer. For example, if the entire sound range is a flesh and blood person, then [low frequency is the basic skeleton of the sound, intermediate frequency is the flesh and blood of the sound, and high frequency is the modification of the sound, that is, the reflection of details.

The audibility of the subwoofer to the human ear is extremely limited, but other senses of the human being can feel it. What exists in the program source and needs to be restored, with it, can make the restoration of the program source more solid, without it, it will give people a feeling of lack of strength and energy. For example, in a movie theater or in reality, we can feel the shock of power and energy when an airplane takes off, but if our home theater is not equipped with a subwoofer or the configuration is unreasonable, we will not be able to feel this shock. That's all.

As far as the audio environment is concerned, in addition to listening to HIFI, whether watching movies or listening to concerts, subwoofer is needed and should be guaranteed. The designation of 0.1CH as an independent subwoofer channel in the two major audio restoration standards of digital home theater also explains its significance and function, which is a must. But it is also possible to compromise. The reason for compromise. Because of the restoration of the subwoofer, as a standard drafter, of course, it is difficult to popularize it, because the cost is huge. Without the help of other technologies, the bass reproduction unit should be a large-diameter unit. In addition, driving such a large-diameter unit also requires a high-power amplifier, which will increase the cost of restoring the subwoofer.

Of course, we can also buy subwoofers with low sales prices in the market. This is actually another kind of compromise. Technically speaking, it is just a fake subwoofer, but from the perspective of the commodity and consumer market, this is also a market preference. need.

But please keep in mind that the subwoofer is the soul of the entire home theater audio system, and the entire magnificent scene is realized by the subwoofer, so if you want to improve the effect of the home theater, starting with the subwoofer is the fastest way to achieve results.

2. Active subwoofer and passive subwoofer

As mentioned above, the subwoofer requires powerful power to drive, so most subwoofers on the market have built-in amplifiers, that is to say, the speakers and amplifiers of the subwoofer are separated and integrated into one.

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

3. The unit diameter of the subwoofer

Strictly speaking, the subwoofer should use a large-diameter unit, and generally a specially designed unit. According to the actual listening comparison of various subwoofers at home and abroad that have participated in the evaluation, the effect of this large-diameter subwoofer is the best.

But the market needs are multi-faceted. Under certain conditions, it is not possible to place a large subwoofer. In addition, some consumers also like small and compact products, so there are small subwoofers. This kind of subwoofer is usually obtained by technical means, such as Boss and Yamaha. The former is the technology of box design, and the latter is the technology of circuit design. But no matter how shocking this kind of subwoofer is, the "fake" in it is difficult to conceal. Please understand the "fake" I said accurately, and don't spread it, so as not to cause unnecessary misunderstandings and misunderstandings.

4. Description of the frequency division circuit of the subwoofer

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

In the digital home theater audio decoding specification, the output 0.1CH signal itself is already a subwoofer signal. Therefore, for newer systems, whether the subwoofer has a low-pass filter or not has no effect on the operation of the subwoofer.

For those who try to use the subwoofer in the two-channel music system, because the usual signal source or power amplifier does not have a separate subwoofer signal output, it is necessary to extract the subwoofer signal on the basis of the existing system. Therefore, it is not necessary In order to achieve multi-purpose and multi-purpose or competition needs, a low-pass filter is designed in the subwoofer, and two extraction methods are designed:

1. It is extracted from the low-level signal output of the signal source, usually an RCA input port, which can be connected with a pair of signal lines or a single signal line.

2. To extract high-level signals from the left and right speakers, generally use the same terminals as the speaker terminals on the power amplifier. As above, the effect of using two pairs of thinner speaker cables or a pair of speaker cables is basically the same.

5. Setting of cut-off frequency

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

The setting of this cutoff frequency is an important debugging environment for playing subwoofers. It is used to debug the frequency connection between the subwoofer and the speakers. If the connection is good, the system performance will be perfect. If the connection is not good, some signals will be lost or the signal will be destroyed. It's changed.

Generally speaking, for bookshelf boxes and small-diameter speakers, the cutoff frequency should be higher, and for floor-standing speakers, the setting should be lower. It usually depends on the lower limit of the low frequency restoration of the speaker.

For example, if the lower limit of the low frequency of a speaker is 60Hz, it is more reasonable to set the cutoff frequency of the subwoofer at 60-80Hz. If it is too high, the bass at 60Hz will be too much. If it is too low, the sense of energy of the 60Hz signal will be lost.

For digital home theater power amplifiers, the power amplifier itself has bass management settings, and the cut-off frequency settings of the subwoofer are adjusted in combination with the size settings of the speakers.

Six: Phase (English phase)

Most subwoofers are designed with a phase adjustment switch, and the phase adjustment of advanced subwoofers is still continuous.

Phase adjustment is relatively simple, normal phase or reverse phase. The correct setting should be that the sound of the subwoofer is relatively solid and shocking. If the sound becomes ethereal after the subwoofer, then the phase switch should be changed immediately.

7. Connection

For home theater systems, it is recommended to use low-level signal input for subwoofer signals. Usually there are 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 connecting it from the AV amplifier, which can be The subwoofer volume is controlled synchronously by the AV power amplifier. If it is taken from a disc player, when the system volume is changed, the volume of the subwoofer needs to be adjusted at the same time. This kind of connection, usually in stereo mode, the subwoofer can't get the signal, so it doesn't help or improve the system much, this needs to be paid attention to.

If you are trying to get the full-band signal from the stereo signal to the subwoofer, you must first make sure that your subwoofer has a low-pass design, otherwise, the subwoofer cannot be used. In this case, the subwoofer of any program can be enhanced.

Eight, positioning

Strictly speaking, the subwoofer lacks directionality, so it can be placed anywhere in the listening room, but considering the huge impact of the environment on sound transmission, in practice we still strongly find that moving the subwoofer's pendulum Positioning has a great influence on the reproduction of the subwoofer. Generally, the subwoofer is placed at one-third of the front wall, but when conditions permit, we still recommend users to adjust the placement of the subwoofer to obtain the best effect.

Finally, it should be noted that the subwoofer does not always exist in the program source, so don't misunderstand it when listening or debugging. Because of habits, people will inevitably use their ears to hear whether the subwoofer is working or whether it is shocking when debugging. In fact, it is unnecessary, and it is enough to feel it with the body. In order to facilitate debugging, special subwoofer signals are usually provided in the test discs on the market.