What is the role of the subwoofer of the speaker?

In many cases of home theater system construction, the selection and adjustment of subwoofer speakers are the most easily overlooked.

Many users don't even understand why a home theater system must have a subwoofer speakers? Can't the main speaker replace the subwoofer speaker? Or is there no clue when choosing a product. Is the larger the subwoofer speaker size, the better the effect? How to adjust the phase of the subwoofer speaker? For practical purposes, interpret the doubts or problems encountered.

1. Subwoofer is essential

Whether it is the Dolby Digital, DTS built in early DVD, or the current sound encoding such as Dolby Atmos, Dolby HD, DTS True HD, etc., there are independent subwoofer speaker channels.

That is to say, under the standard of these formal multi-channel sound effects encoding, one or more active subwoofer speakers must be matched to show the midrange, bass and even subwoofer speaker that should be in the audio. frequency band.

2. Don't judge the quality by the size of the subwoofer

The size of the subwoofer speaker involves factors such as the driving power of the  subwoofer speaker itself, the type of the box, the efficiency and instantaneous performance of the single unit.

Although a large-sized subwoofer speaker can push the air with a larger area, thereby producing a more component low frequency, but it has a much heavier cone weight than a small-sized subwoofer speaker. If you want to push it out for a stronger low frequency, In the amplifier circuit part, it is necessary to have stronger output power first.

In addition, the instantaneous performance of large-sized subwoofer speaker is often not as good as that of small-caliber subwoofer speakers, so the speed of low-frequency transmission is often not fast enough, and even the phenomenon of sound "smearing" occurs. Therefore, the use of large-sized subwoofer speakers mostly only provides larger low-frequency components, and it may not be as light and agile as small-sized subwoofer speakers in the sense of speed.

3. Main speakers instead of subwoofer speakers? Sound effects at a discount

The home theater system cannot determine whether the mid- and low-frequency range (especially the low-frequency part) of the entire combination is sufficient by the size of the speaker alone, because the normal multi-channel system will most likely cross the frequency band below 80Hz or 90Hz of the response frequency band. Take responsibility for the subwoofer speaker. For users who do not consider buying a subwoofer speaker, the main speaker can also be set to full frequency through settings.

But this setting is bound to cause a greater burden on the amplifier circuit of the main speaker and the cinema power amplifier itself. In addition, the subwoofer speaker can independently adjust the volume, crossover point and phase, and can also adjust the placement according to the size of the space. Home theater systems with subwoofer speakers have more flexibility in overall debugging.

4. Subwoofers are phase-sensitive

Simply put, in the placement adjustment of the subwoofer speaker, when the subwoofer speaker and the left and right channel speakers both sound in the same direction, the sounding phase of the two should be close to the same phase angle.

If the subwoofer speaker is placed in a "hedged" position with the speaker, the subwoofer speaker will form a 180-degree anti-phase state with the left and right speakers. At this time, if the phase of the subwoofer speaker backplane is not set to 180 degrees (reverse phase), 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 emitted. Causes the phase to be inconsistent, and even because of the overlap or cancellation of the phase, the increase or disappearance of some low-frequency frequency bands is formed.

When we adjust the positive and negative phase of the subwoofer speaker, we can follow the low-frequency volume heard at the listening position. That is to say, when we play a song with a full sense of low frequency, you can sit in the listening position, and then switch the positive and negative phases of the subwoofer speaker in turn, as long as you can feel the strong low frequency effect in the listening position, then The phase is even the one that makes you feel the low frequencies.

5. The low frequency is a mess, how should we debug it?

Generally speaking, subwoofer speakers often cause some frequency bands to disappear, but some frequency bands to be excessive because of the frequency band, phase cancellation or increase in space.

First of all, when we are adjusting the subwoofer speaker, we can start from the four parts of the subwoofer placement and angle, phase selection, volume and crossover point as adjustment items. During the initial debugging, we can adjust the volume first, and finally adjust the appropriate volume. After the problem of low frequency confusion is improved to a certain extent, use the music and movies that you are familiar with as playback detection. After adjusting the settings several times in this way, the effect of the subwoofer speaker will be improved to a certain extent.