Take you to understand the subwoofer

                              Take you to understand the subwoofer

Presumably everyone knows the role of the subwoofer. As a part of the home theater system, it is responsible for regenerating the low-frequency sound effects in the movie sound effects, which are used to make up for the lack of low-frequency volume of the main speaker, or the low-frequency and extremely low-frequency areas that cannot be reached (or As a massage chair, coffee table or something).

If the subwoofer is classified by whether it has a built-in amplifier, it can be divided into two types, one is an active subwoofer, and the other is a passive subwoofer. If it is distinguished by box design, it can be roughly divided into low-frequency reflection design, bandpass design, transmission line design, etc. If it is distinguished by the direction of the sound, it can be divided into sounding toward the front, sounding toward the back, sounding toward the ground, sounding toward the top, and sounding toward the left and right sides. If it is distinguished by a single action mode, there is a push-pull type composed of two speakers. The same-phase sounding type composed of two or three, the same-phase sounding type composed of a single passive radiator. Among them, the most ideal subwoofer is designed with a set of bass equalization circuit in addition to the built-in amplifier, which can moderately attenuate the indoor medium and low frequency standing waves to a certain extent, so that the low frequency band below 100HZ or 80HZ can reach a relatively low frequency. Flat frequency response curve. Of course, the price of the gun of this design is also quite expensive.

Generally speaking, closed subwoofers and inverted (bass reflex) subwoofers are the most common types, and they are also the most commonly used subwoofer types by general users. The closed subwoofer box itself is airtight, and there are no holes or gaps communicating with the outside world. The woofer can be placed facing the front, rear, left, right, up and down. This form of subwoofer has fast transient response, can withstand high power, and the volume of the box can also be made relatively small, such as SVSound’s SB-1000 Pro, SB-2000 Pro, SB4000 and SB16-Ultra, all of which are small The figure has a representative of great energy.

The inverted (bass reflex) subwoofer box itself has one or more bass reflex holes, so that the front wave of the woofer in the box can be transmitted out of the box through the bass reflex hole, and mixed with the positive wave of the woofer. Leverage to increase the volume of low frequency. The distortion is relatively low, and the power amplifier is relatively large. Compared with the closed box, the lowest cut-off frequency of the bass reflex type can be lower, but the instantaneous response and dynamic sense are not as fast and powerful as the closed box, such as PB-1000Pro, PB-2000Pro, PB3000, PB4000 and PB16-Ultra, strong low-frequency sense and low-frequency dive depth are the characteristics of this type of subwoofer.

The other two types of subwoofers are bandpass and transmission line subwoofers. These two types are relatively rare because of their relatively high production cost. At present, there are many active subwoofers on the market. The active subwoofer has a built-in amplifier, such as SVSound’s Thor’s Hammer amplifier, which can provide strong power for the subwoofer. Since the amplifier is built-in, the subwoofer needs to be connected to the AV amplifier to obtain low-level music signals. Taking the active subwoofer as an example, most subwoofers have RCA and balanced interfaces in terms of input and output.

Function adjustment is a necessary setting for the subwoofer, generally speaking, it has volume adjustment, phase adjustment and low-pass filter adjustment. Phase adjustment is continuous or segmented adjustment from 0-180°. Why do you need phase adjustment? Simply put, when the low frequency emitted by the subwoofer is mixed with the low frequency emitted by other speakers, if the phases of the two are consistent or close, the total low frequency sense is the sum of the two additions. Conversely, if the phases of the two are opposite or nearly opposite, the overall sense of low-frequency volume will be subtracted. Theoretically, when the cannon is on the same horizontal line as the main box and the center, its low-frequency phase should be the same or close to the main box and the center. In fact, due to many factors, it is impossible to place the cannon on the same horizontal line as the main box and the center, but more in the corner or on the side. At this time, the sound phase of the cannon may be different from that of other channels, and it has a phase Adjustment can be adjusted freely.

Low pass filter adjustment, there is a filter on the subwoofer. The low-pass filter generally has a continuous or segmented adjustment range from 50Hz to 160Hz. When you adjust it to a setting of 70Hz, the low-frequency level signal will show a frequency below 70Hz on the supersonic gun. In other words, when adjusted to X Hz, the subwoofer will be able to emit sound at frequencies below XHz.