Many friends who have installed a home theater, do not understand why a subwoofer is added? Is the subwoofer bigger and better? What should I do with low frequency paste? How to adjust the phase of the subwoofer? For practical purposes, don't talk too much theory. The technical problems are directly explained by the doubts or problems encountered by friends.
â–ŒIn order to restore realistic multi-channel sound, the subwoofer is essential.
Whether it is the early DVD built-in Dolby Digital, dts, or the current Dolby Atmos, Dolby HD, dts True HD audio coding, there are planned independent subwoofer channels, that is to say in these regular multi-channel audio coding Under the norm, it is necessary to cooperate with one or more active subwoofers to display the medium and low frequency bands that should be present in the audio and video software.
▌ Do not judge the quality of the subwoofer by the size of the subwoofer.
Many users believe that the size of the unit equipped with the subwoofer must be as large as possible. In fact, this problem involves the driving power of the subwoofer itself, the type of the box, the efficiency of the unit and the instantaneous performance. Large-size monomers can push the air in a larger area, resulting in a more low-frequency, but the large monomer has a much heavier cone weight than the small-sized monomer, and wants to push it out to a stronger low frequency. In the amplifier circuit, the first step is to have a stronger output power.
In addition, the instantaneous performance of large-sized monomers is often no smaller than that of small-diameter cells. Therefore, the speed-sensing part of low-frequency transmission is often not fast enough compared with smaller-caliber monomers, and even produces a "tailing" of sound. The phenomenon. Therefore, most of the subwoofers that use large-size monomers provide only a larger amount of low-frequency parts, and in the sense of speed, they cannot be as light and agile as small-caliber singles.
According to such a single characteristic, there have been manufacturers on a speaker, using a plurality of small-diameter woofer to arrange a subwoofer with the same or even larger area as a large-diameter unit, which is better by a small-sized monomer. Control and transient performance, plus a number of cells arranged in the same air drive area as the bulk, forming a perfect subwoofer that is fast and capable of producing the same energy as a large diameter cell. However, such a subwoofer is quite elegant in terms of a single unit, a box and an AV power amplifier. Regardless of the actual effect, it may not be acceptable to the general consumer at the price part.
▌ Left and right channel woofer to force, do you still need to add a subwoofer?
The AV system can not determine whether the middle and low range (especially the low frequency part) of the whole set is sufficient by the size of the single speaker. The reason is that the regular multi-channel system will mostly pay the frequency band below 80Hz or 90Hz in the response band. Responsible for the subwoofer. Of course, if you don't have a subwoofer, you can also set the front left and right channels to the full range from the AV amplifier menu.
However, such a 5.0 channel, 7.0 channel setting is bound to impose a greater burden on the front left and right channels and the amplification circuit of the AV power amplifier itself. Even if you use high-efficiency AV amplifiers with high-power left and right channels and high-power output, the low-frequency performance should be no better than the built-in AV amplifier, and the active single bass of individual units should be better. In addition, the exclusive dedicated active subwoofer can independently adjust the volume, crossover point and phase. The individual cabinets can be freely selected according to the space and the speaker position. For the mid-low range of the whole multi-channel system. The adjustment part is also more flexible than the 5.0 channel.
Although the bass has no direction, the subwoofer is phase-oriented.
Phase is a measure of the change in signal waveform, usually in degrees. When a complete waveform is from the peak to the valley and then return to the origin, the positive and negative sine waves are 360 ​​degrees, which means that when the waveform is halfway to 180 degrees, it is exactly opposite to 0 and 360 degrees. Wave type. To put it simply, in the adjustment of the subwoofer, when the subwoofer and the left and right channel speakers both sound in the same direction, the vocal phase of the two should be close to the same phase.
If the subwoofer is placed in a "hedged" position with the horn, the subwoofer will be 180 degrees out of phase with the left and right horns. At this time, if the phase of the subwoofer backplane is not set at 180 degrees (inverted) position, not only will the subwoofer low frequency always be emitted from the back of the sound field, or some frequency bands between the subwoofer and the speaker will be It will cause phase inconsistency, even because of the overlap or offset of the phase, which will increase or disappear some of the low frequency bands.
There are many reasons for the offset or overlap of the phase from the environment and space. In addition, since the sound phase of the five-channel speaker is different, it is impossible for the subwoofer to select only the front and rear positions. Sometimes, in order to avoid the formation of low-frequency standing waves, the subwoofer may be placed at two-thirds of the side wall to the oblique side. As a result, the phase adjustment part of the subwoofer will complement each other. It has become very complicated.
In the face of the above complex factors, when we adjust the positive and negative phases of the subwoofer, we can follow the low frequency sense heard at the listening position. In other words, when we play a low-frequency drum sound or electro-dance music, you can sit in the listening position, then switch the front and back phases of the subwoofer in turn, as long as you can feel at the listening position. To a strong low-frequency effect, such a phase can make you feel the phase of the low frequency.
Because of this, there are many subwoofers that will be equipped with only the positive and negative (0/180 degree) phase switching function, and upgrade to a mode with 0-180 degrees continuous adjustment or 0-360 degree multi-segment selection. In order to provide the sound system users do not have to bend to the position of the subwoofer, but also to adjust the appropriate phase angle.
▌ About adjusting the crossover point of the subwoofer
Active subwoofers are also generally equipped with crossover point adjustment. Due to the crossover adjustment built into the super bass, it is basically a low-pass filter that can pass the fixed band below the adjustable LPF (Low Pass Filter), that is, if the knob is set to 80Hz, the LPF The input signal below 80 Hz will pass, and the frequency band above 80 Hz will be filtered out.
After figuring out the crossover point of the subwoofer, when we set the crossover point of the subwoofer, we can use it as a reference for adjusting the subwoofer crossover point according to the low frequency extension of the speaker. For example, the low-frequency response of a pair of speakers is indicated as 60Hz. The buckled speaker may have a gradual attenuation characteristic below 80Hz. When adjusting, we can preset the subwoofer crossover point to about 70Hz.
For example, many of the AV power amplifiers set to the front left and right channels are mostly in the frequency band above 80 Hz. At this time, the signal below 80 Hz will be transferred to the signal output terminal connected to the subwoofer, then we can Set the crossover point of the subwoofer at 80Hz. This will not only make the amplifier circuit inside the subwoofer work easier, but also the low frequency sound produced by the subwoofer.
I don’t feel the shock of the subwoofer, even the low frequency is a mess.
Really speaking, the adjustment settings of the subwoofer may be much more difficult than the AV amplifier. AV amplifiers can be set according to the instructions, especially for many new generation models. Just plug in the microphone and press the button, it will help you adjust the system settings in a few minutes. But the adjustment of the subwoofer can't make the user so lazy. In addition to several high-end subwoofer models available on the market equipped with detection microphones, most subwoofers still rely on the user's repeated adjustments from the position, phase, volume and crossover points to get the natural Unobtrusive low frequency effects.
In general, subwoofers often cause some frequency bands to disappear due to frequency bands, phase cancellations or increases in space, while some frequency bands are excessive. Here are some adjustments that most people often use for your reference. First of all, when we are adjusting the subwoofer, we can use the four parts of the subwoofer position and angle, phase selection, volume and crossover point as adjustments.
At this point, you can adjust the volume first, and finally adjust the appropriate volume. After the above problems have been improved to some extent, the familiar music and movies are used as the playback detection. After several adjustments in this way, the subwoofer will be improved to some extent.
Of course, some enthusiasts who love DIY even try to connect the subwoofer to the stereo system. This is a more troublesome proposition and requires sufficient experience and technology to elaborate. Xiaobian is not discussed in detail here. When you grasp the above six points, you basically have a clear understanding of the subwoofer. 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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