Some common sense about the subwoofer

                                      Some common sense about the subwoofer

1. The function and significance of the subwoofer

Subwoofer is a common name or abbreviation for everyone. Strictly speaking, it should be: subwoofer. In terms of audio analysis that can be heard by the human ear, it consists of subwoofer, bass, low midrange, midrange, midrange, treble, superhighpitch, etc.

The low frequency is the basic framework of the sound, the middle frequency is the flesh and blood of the sound, and the high frequency is the detailed reflection of the sound.

With the development of science and technology and the development of economic base, subwoofer and broadband have entered the audio world. The subwoofer is to strengthen the structure, and the broadband is to make the sound difference clearer.

The hearing of the subwoofer is extremely limited to the human ear, but it can be felt by other human senses. This is the shocking feeling! As far as the needs of the audio program source reflected by the audio system and the home theater are concerned, the subwoofer only exists in a specific program source and needs to be restored. With it, the restoration of the program source can be made stronger. Without it, it will give people a lack of power. , The feeling of 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, whether listening to music or watching movies, subwoofer (broadband) is needed and should be ensured. The designation of 0.1CH as the subwoofer channel in the two major audio restoration standards of digital home theater also shows its significance and function. It is necessary, but it can also be compromised. 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 unit for bass reproduction should be large-diameter. In addition, driving such a large-diameter unit also requires a high-power amplifier, which will increase the cost of restoring the subwoofer.

2. Active subwoofer and passive subwoofer

Subwoofer needs 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 independently divided and integrated into one. If there is no amplifier in the subwoofer, it is a passive subwoofer.

3. The unit diameter of the subwoofer

The subwoofer should use a large-diameter unit, and it is 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. However, the market needs are multifaceted. Under certain conditions, it is impossible to place a large subwoofer. In addition, some consumers also like small and compact products, so there is a small subwoofer.

4. Description of the frequency division circuit of the subwoofer

With so many subwoofers being used in home theater systems, subwoofer designs are becoming increasingly 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, and it is possible to connect 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 wires or a pair of speaker wires is basically the same.

5. Setting of cut-off frequency

The critical point of the low-pass filter 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.

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 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 a full-band signal from a stereo signal into a subwoofer, you must first make sure that your subwoofer has a low-pass design, otherwise, the subwoofer cannot be used. In this case, any program can be enhanced with sub-bass.

Eight, positioning

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, we still strongly found that moving the subwoofer’s position has a great impact on the subwoofer’s sound transmission. The restoration of the bass has a relatively large impact. When conditions permit, we still recommend that the user 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. For the convenience of debugging, special subwoofer signals are usually provided in the test discs on the market.