Subwoofer

Bass speaker

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synonym Subwoofer (Electronic equipment) generally refers to subwoofer (subwoofer)

Subwoofer is a common name or abbreviation of everyone. Strictly speaking, it should be: subwoofer. Bass In English, it means super bass, which means the bass with heat and energy. As the name implies, the function of bass is to strengthen bass band , that is to improve the long wave Some (below 100HZ, even including Infrasonic wave , although people can't hear it, it is still effective), because ordinary speakers are limited in size and cannot emit longer wavelength Low frequency sound, so a larger subwoofer is needed to produce low frequency sound warm The effect of.

The concept of "subwoofer" was innovatively developed for the first time, while the term "subwoofer" with local characteristics was developed by Mai Lan (now Maibo ）Pioneering. This is a comparison down to earth , because its playback effect is like Spring Festival Time release firecrackers equally warm Cheerful , full enthusiasm , which is called "subwoofer". In the enthusiastic and cheerful dance, the subwoofer is also indispensable, because the music it plays can make the dance more passionate and dynamic, hot, lively and dynamic.

As far as an audio analysis is concerned, it is composed of subwoofer, bass, mid bass, midrange, alto, treble, and ultrahigh. They have the effect of forming and strengthening the rhythm of syllables. And the bass speaker has the longest sound wave, which can make your heart produce exciting sounds, so that your heart can jump crazily with the beat. In a nutshell, bass (long wave) is the vitality and vitality of sound（ Medium wave ）It is the flesh and blood of sound, and the treble (short wave) is the detail reflection of sound.

Chinese name: Bass speaker
Foreign name: subwoofer

Commonly known as: Subwoofer
Classification: Entertainment equipment

catalog

principle

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The subwoofer is a subwoofer, which specializes in the longest sound wave wavelength At the longest, it sounds very obvious to people. The psychological feeling will be very warm, and people's other senses will also feel it. This is an exciting feeling! On audio and Home theater As far as the needs of the audio program source are concerned, bass exists in a specific program source and needs to be restored. With it, the restoration of the program source can be more cheerful and full of enthusiasm. Without it, people will feel lack of enthusiasm and energy. For example, in the cinema or in reality, the bass is very hot, so we can feel the hot when the plane takes off passion However, if our home theater is not equipped with a bass speaker or the configuration is unreasonable, we cannot feel this passion 。 To put it bluntly, it can make your heart produce exciting sounds, and your heart can jump wildly with the beat.

The internal power amplifier circuit divides the sound into several wavelength segments through the wave divider. The output of the short and medium wave bands (mid treble) is sent to the satellite speaker, and the output of the long and medium wave bands (mid bass) is sent to the subwoofer. Generally, the subwoofer sends 20-200 HZ The long wave sound is easy to hear, but because of its wavelength Long, it is difficult to distinguish the direction of sound source, such long wave sound passes through Inversion hole Outgoing, it resonates with the satellite speaker speaker. The weak bass produced by the longwave speaker and the satellite speaker speaker is combined, and the satellite speaker speaker will re perform the speaker to release the bass. Therefore, the bass effect is very warm, and it makes people feel like it is emitted from the satellite speaker speaker. Here you should basically understand the principle of the speaker, as to why to use it Ultralong wave Horn and long wave Resonant horn It needs to be understood with physical knowledge: satellites are weak bass, although they can be heard by people, their waveform amplitude Very small, that is, the energy is not enough. If the long wave technology is used, when the ultra long wave generated by the speaker overlaps with it, their phase is consistent due to passing through the inverted hole, then the ultra long wave will be loaded onto the waveform of the satellite bass. Because the speaker has a very powerful power, the energy will increase sharply after loading, which makes you feel very excited.

type

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Generally speaking, subwoofers can be divided into active subwoofers and Passive subwoofer Two types. An active subwoofer is a subwoofer with a built-in power amplifier. It does not need to add another power amplifier when in use. It is usually cylindrical in shape. This kind of subwoofer deficiencies The reason is that the heat dissipation is not ideal, the power is not very large, and the barrel shape usually produces unnecessary resonance Phenomenon that causes the subwoofer's Controllability Down. In contrast, the passive subwoofer requires an external power amplifier to work. The shape and power selection of this subwoofer can be more flexible, and the effect is naturally more ideal. In addition, active speakers can be divided into Sealing box The playing effect of the former is magnificent and warm, but there are subtle differences between the former and the perforated box. The former is more suitable for the magnificent military music The latter is more suitable for enthusiastic and surging pop music.

It seems that the use of subwoofer is very high. It often appears around young people who like high music. They like pop music Rock music A must for dance music owners. In principle, the subwoofer and speaker The working mode of is exactly the same, except that the diameter of the diaphragm is larger, usually 8-10 inches, and the speaker for resonance is added.

evaluating indicator The subwoofer is basically the same as the loudspeaker, but the specific contents will not be introduced here, just the numerical requirements. The wavelength response is generally below 200 Hz, that is, above 1.7 m, the rated impedance is also about 4 Ω, and the sensitivity is generally greater than 90 dB/W/m.

texture of material

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Low grade plastic speakers cannot be overcome due to their thin box material resonance , there is no sound quality to speak of. The wooden speaker reduces the noise caused by box resonance Phonogram The sound quality is generally better than that of plastic speakers. usually Multimedia speaker Both are of dual unit two wave design. One smaller speaker is responsible for the output of medium and high tones (medium and short waves), while the other larger speaker is responsible for the output of medium and low tones (medium and long waves).

The materials of these two speakers should be considered when selecting speakers: multimedia Active Speaker The tweeter of is mainly soft dome (in addition, it is also used for Analog sound source Titanium film dome, etc.), which can reduce the High frequency signal The stiff feeling gives people a cool and comfortable feeling. Multimedia speakers are now of good quality Filamentous membrane And low cost PV membrane. Bass unit determines the sound characteristics of speakers, and is relatively important to choose. The most common ones are as follows: Paper basin , adhesive paper basin Paper-based Wool basin, compact pressing basin, etc. Paper basin has natural sound, low price, good rigidity, light material and high sensitivity. Its disadvantage is poor moisture-proof, and it is difficult to control the consistency during manufacturing HiFi Paper pots are used everywhere in the system because the sound output is very average, Reducibility Good; Bulletproof cloth, with wide wave sound and low distortion, is the first choice for those who love warm bass. Its disadvantages are high cost, complex production process, low sensitivity and poor music effect; Wool woven basin, soft in texture Soft music The performance of soft music is very excellent, but the bass effect is poor, lacking heat and passion; PP( polypropylene ）Basin, it is widely popular in high-end speakers, good consistency and low distortion, and all aspects of performance are commendable. In addition, fiber like diaphragm and compound material Due to the high price, diaphragm is rarely used in popular speakers, so we will not talk about it.

The speaker size is naturally the larger the better, large caliber Woofer It can perform better in the long wave part, which can be selected during shopping. The speaker made of high-performance speakers means lower transient distortion and better sound quality. The loudspeakers of ordinary multimedia speakers are mostly 3-5 inches. The speaker made of high-performance speakers also means lower transient distortion and better sound quality.

structure

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From the structural form, speakers can be divided into bookcase type and floor type. The former is small, so its power is limited, and the wavelength limit of long wave band is insufficient, which is suitable for appreciation High Fidelity Music The main music lovers are also our first choice for entry-level multimedia enthusiasts; The latter is large in size and power, strong in intensity and enthusiasm of long wave, and good at expressing torrential enthusiasm and strong passion.

For different music lovers, this is also an important content to understand before purchasing. Since few PC users have the conditions to place large floor boxes, smaller desktop bookshelf speakers should be the first choice for multimedia active speakers. In general: as long as the power amplifier Module design Reasonable. The bigger the box, the bigger the horn, and the more pleasant the sound.

Circuit composition

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In terms of the composition of the subwoofer circuit, it is generally composed of the front amplifier and the long pass wave filtering , phase adjustment, power amplification, protection and power supply. As far as its function is concerned, the former stage amplification is to AV power amplifier Output Bass The signal is further amplified enough Drive power Enlarged part is full power output Because the voltage of the subwoofer signal provided by various brands of AV power amplifiers is different, generally ranging from 0.3-1 V, the front stage amplification is necessary. The front stage circuit also plays an important role in isolation and buffering. Because the subwoofer signal output by various brands of power amplifiers is different, some manufacturers steal materials in design, resulting in their output internal resistance Very high, if direct drive The power amplifier unit of the subwoofer may have very poor effect; Long pass filtering is a subwoofer Internal circuit Part is an important unit, which is used to mix the power amplifier output long wave The signal below the long wave in the signal is further filtered out, and the general design will be 80-180Hz (many high-end products will wave filter Long end Cut-off wavelength It is designed to be continuously adjustable). If it is a fixed wavelength filter, the value is generally about 110-150Hz; There is no uniform regulation on whether the subwoofer signal output by AV power amplifiers of various brands is in reverse or in positive phase. Therefore, phase adjustment is to use the subwoofer in positive or negative phase according to the needs of system connection when placing the subwoofer, depending on the effect, which is generally necessary; The power amplifier unit doesn't need to be wordy, yes Active The core of the subwoofer is. Similarly, in order to protect the subwoofer from safe operation and protect the equipment from damage to valuable parts or expansion of faults in case of abnormalities, protection circuit It is generally necessary; The power supply is the power of each circuit unit and the basic component. What needs to be added is that some subwoofers have also designed an automatic power control function, so that the subwoofer can automatically turn off the main power supply of the subwoofer when there is no signal.

function

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extend

It refers to whether the speaker supports Multichannel Input at the same time, whether there is passive connection Surround speaker Of Output interface , Yes No USB Input function, etc. The number of subwoofers that can be connected to external surround speakers is also one of the criteria to measure the expansion performance. The interfaces of ordinary multimedia speakers mainly include analog interface and USB interface Two, others such as Optical fiber interface There are also not many digital interfaces dedicated to innovation, so no introduction will be given.

Sound effects

Hardware 3D sound effect Common technologies are SRS , APX, Spatializer 3D, Q-SOUND, Virtaul Dolby and Ymersion, although they have different implementation methods, can make people feel obvious 3D sound field effects, of which the first three are more common. They all apply extensions stereo (Extended Stereo) theory, which is to make the listener feel that the audio-visual orientation extends to the outside of the two speakers by additional processing of the sound signal through the circuit, so as to expand the audio-visual and make people have Sense of space and Stereoscopic feeling To produce a wider stereo effect. In addition, there are two sound enhancement technologies: active electromechanical servo technology (essentially using Helmholtz resonance principle) BBE High definition plateau intensity discharge System technology And "phase fax" technology, which also has a certain effect on improving the sound quality. For multimedia speakers, SRS and BBE technologies are relatively easy to implement and have a good effect, which can effectively improve the performance of speakers.

tone

It refers to a signal with a specific and usually stable wavelength (pitch), which is generally the tone of sound. It mainly depends on the wavelength. For sound with short wavelength, the human ear responds with high pitch, while for sound with long wavelength, the human ear responds with low pitch. Tone changes with wavelength basically logarithm Relationship. Different instruments play the same note. Although their timbre is different, their tone is the same, that is, they play the same sound Fundamental wave Is the same.

timbre

The feeling of sound quality is also the characteristic quality that distinguishes one voice from another. When different musical instruments pronounce the same tone, their timbre can be different. This is because although their fundamental waves are the same harmonic The composition varies greatly. Therefore, the timbre not only depends on the fundamental wave, but also is closely related to the harmonics that form an integral part of the fundamental wave, which makes each instrument and each person have different timbres. However, the actual description of the timbre is more subjective and may feel more mysterious.

dynamic

The ratio of the strongest to the weakest in sound, expressed in dB. For example, a band's dynamic range 90dB, which means that the power of the weakest part is 90dB lower than that of the loudest part. The dynamic range is the ratio of power, independent of the absolute level of sound. As mentioned earlier, the dynamic range of various sounds in nature varies greatly. The general language signal is only about 20-45dB, some Symphony Its dynamic range can reach 30~130dB or higher. However, due to some factors, Audio system The dynamic range of the band can rarely reach the dynamic range of the band. The internal noise of the recording device determines the weakest sound that can be recorded, while the maximum signal capacity (distortion level) of the system limits the strongest sound. Generally, the dynamic range of sound signal is set as 100dB, so hi-fi equipment The dynamic range of 100 dB is very good.

Total harmonic

Refers to audio signal source adopt power amplifier Because Nonlinear element Caused by output signal than Input signal Additional harmonic components. Harmonic distortion Because the system is not completely linear, we use the new total harmonic component Root mean square With the original signal Valid values Of percentage To represent. For example, when an amplifier outputs 10V 250Hz plus Lv 500Hz, there will be 10% second harmonic distortion. All additional harmonics level The sum is called Total harmonic distortion 。 Generally speaking, the total harmonic distortion at 500Hz is the smallest, so many products take the distortion of this wavelength as its index. However, the total harmonic distortion is related to the wavelength, so Federal Trade Commission In 1974, it was stipulated that the total harmonic distortion must be measured in the full band of 20~20000Hz, and the amplifier's maximum power It must be measured under the condition that the load is 8 Ω loudspeaker and the total harmonic distortion is less than 1%. International Electrotechnical Commission The minimum required total harmonic distortion is 0.5% for the front amplifier and 0.5% for the combined amplifier Less than or equal to 0.7%, but in fact, it can reach below 0.1%: FM stereo tuner Less than or equal to 1.5%, actually less than 0.5%; The CD player can achieve less than 0.01%.

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