The gunners came over and talked about the subwoofer.

If the home theater doesn't have a subwoofer, then at least half of the fun of watching a movie can be cut in half. In reality, it is not so fun, because many people really don't have a subwoofer. So, we made some Q&A on some of the most basic problems about the subwoofer, hoping to help the readers of the Chinese home theater network.

Q: Do you have a subwoofer for multichannel systems?

A: Whether it is the early DVD built-in Dolby Digital, dts, or the current BD Dolby HD and dts True HD audio coding, there are planned independent subwoofer channels, that is to say in these regular multi-channel audio coding Under the specification, one or more active subwoofers must be combined to show the medium and low frequency bands that should be present in the audio and video software.

Q: My front left and right channels are equipped with 10 吋 woofer, so do I need to add a subwoofer to the system?

A: This is also a question that many theater multi-channel system users will have, but 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. Regular multi-channel systems will mostly be responsible for the frequency band below 80Hz or 90Hz in the response band. 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 surround amplifier menu. However, such a 5.0 channel setting is bound to impose a greater burden on the front left and right channels and the amplifying circuit of the surround amplifier itself.

Even if you use a high-efficiency surround amplifier with high-power output and high-power output, the low-frequency performance should be no better than the built-in amplifier, and the active single bass of the 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.

Q: Why do you not feel the shocking effect after adding a subwoofer to the system, or is it a low-frequency boom?

A: Really speaking, the adjustment settings of the subwoofer may be much more difficult than the surround amplifier. The surround amplifier can be set according to the instructions, especially for many new generation models. Just press the button on the microphone and you can 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 offsets or increases in space, while some frequency bands are excessive. Here we provide the adjustment methods that avstyle often uses for your reference. First of all, when we are adjusting the subwoofer, we can use the four parts of "subwoofer position and angle", "phase selection", "volume part" and "divide point adjustment" as the adjustment target. The "Volume Part" can be adjusted first, and finally the volume is adjusted. After the above problems have been improved to a certain extent, use your familiar music CD or DVD movie as a playback test. I believe that after several adjustments in this way, I believe that there will be a certain degree of improvement.

Q: What is the phase of the subwoofer? How to adjust?

A: 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 erection 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, the sound phase of the five-channel speaker is different, and the subwoofer is less likely to be placed only in front and back. Position, sometimes in order to avoid the formation of low-frequency standing waves, the subwoofer may be placed on the side wall by two-thirds of the side wall, so that the phase adjustment part of the subwoofer will complement each other. And thus 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.

Q: How to adjust the crossover point of the subwoofer?

A: Today's active subwoofers are also equipped with crossover adjustments in addition to volume and phase 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.

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