Type and performance index of the hottest speaker

Type and performance index of speakers

speakers are also known as speaker system, which is a very important link in the sound system. Because the playback quality of speakers has a great impact on the whole sound system. At present, the level of program signal source equipment and power amplifier has been comprehensively improved, and the industrial quality is very high. Therefore, the playback quality of a sound system composed of high-quality sound source, high-quality amplifier and speaker system mainly depends on the speaker

I. types of loudspeakers

there are many classification methods of loudspeakers, which are commonly classified in professional acoustics as follows:

1 According to the occasion of use: it is divided into professional speakers and household speakers. Household speakers are generally used for family playback, which is characterized by fine and soft playback sound quality, exquisite appearance, low playback sound pressure level and relatively less power. Professional speakers are generally used in song and dance halls, karaoke halls, cinemas, auditoriums, stadiums and other professional entertainment places. General professional speakers have high sensitivity, high playback sound pressure, good strength and large bearing power. Compared with household speakers, their sound quality is hard and their appearance is not very exquisite. However, the performance of monitoring speakers in professional speakers is close to that of household speakers, and their appearance is generally exquisite and small, so this kind of monitoring speakers are often used by household hi fi sound systems

2. According to the playback rate, it can be divided into full band speakers, subwoofers and subwoofers. The so-called full band speaker refers to the sound that can cover the low-frequency, intermediate frequency and high-frequency range. The lower limit frequency of full band speakers is generally 30hz-60hz, and the upper limit frequency is 15khz-20khz. In general small and medium-sized sound systems, only one or two pairs of full band speakers can fully undertake the playback task. Subwoofer and subwoofer are usually special speakers used to supplement the low-frequency and ultra-low-frequency playback of full band speakers. This kind of speaker is generally used in large and medium-sized sound systems to strengthen the strength and shock of low-frequency playback. When in use, most of them pass through an electronic frequency divider (sound divider) and send the low-frequency signal to a special bass power amplifier, and then push the bass or subwoofer

3. According to the purpose: generally, it can be divided into main playback speaker, monitoring speaker and back listening speaker, etc. The main playback speaker is generally used as the main speaker of the sound system to undertake the main playback task. The performance of the main playback speaker has a great impact on the playback quality of the whole sound system. You can also choose a full band speaker plus a subwoofer for combined playback

monitoring speakers are used for program monitoring in control rooms and recording rooms. They have the characteristics of small distortion, wide and straight frequency response, and little modification of signals, so they can most truly reproduce the original appearance of the program. Return listening speakers, also known as stage monitoring speakers, are generally used on stage or in song and dance halls for actors or band members to monitor their own singing or performance. This is because they are located behind the main playback speaker on the stage and can't hear their own voice or the band's performance clearly, so they can't cooperate well or can't find the feeling, which seriously affects the performance effect. Generally, the return speaker is made into an inclined plane shape and placed on the ground, so that it can not only be placed on the stage without affecting the overall shape of the stage, but also be heard clearly by the people on the stage during playback, and the new sound regulations are not intended to limit the negative impact of plastic bags on the environment, and the sound is fed back to the microphone to create a roar

4. According to the box structure, it can be divided into sealed speakers, inverted speakers, labyrinth speakers, acoustic tube speakers and multi cavity resonant speakers. Among the professional speakers, the inverted speaker is the most widely used one, which is characterized by wide frequency response, high efficiency and large sound pressure, and conforms to the type of professional sound system speaker. However, due to its low efficiency, it is less used in professional speakers, mainly used for household speakers, and only a few monitoring speakers adopt closed box structure. The sealed speaker has the advantages of simple debugging, wide frequency response and good low-frequency transient characteristics, but it has high requirements for the dialer unit. At present, among all kinds of speakers, the inverted speaker 283 steel structure fire retardant coating and sealed speaker account for the majority. Other types of speakers have a variety of structural forms, but account for a small proportion

second, the performance index of the loudspeaker system

1) frequency response (effective frequency range)

this index reflects the main frequency range of the loudspeaker. When a constant voltage signal source is applied to the loudspeaker and the frequency of the signal source is changed from low frequency to high frequency, the sound pressure generated by the loudspeaker will change with the change of frequency. The sound pressure frequency curve thus obtained is the frequency response curve of the loudspeaker. IEC (International Electrotechnical Commission) stipulates that the frequency limit of the sound that can be reproduced by the loudspeaker, that is, the effective frequency range, is the frequency range in which the average sound pressure level in the loudspeaker sound pressure frequency characteristic curve is 10dB lower than the average sound pressure level of one octave near the peak. The wider the range, the better the sound reproduction characteristics

generally, the minimum frequency response of the speaker box for high fidelity is Hz (+4~-8db), and it is enough to reach Hz Of course, Hz is better

2) rated impedance

it refers to the impedance value measured at the input end of the loudspeaker at a specific working frequency (intermediate frequency). It is usually indicated on the nameplate of the product trademark and given by the manufacturer. Impedance characteristics of loudspeaker. The rated impedance given by the manufacturer is usually the impedance modulus that can be expected to get the maximum work in the rated frequency range. The rated impedance is generally 4 Ω, 8 Ω, 16 Ω, 32 Ω, etc., and 3 Ω, 6 Ω, etc. are also used abroad

3) power

the power of speakers is one of the important indicators for choosing to use speakers It should be pointed out that there are great differences in the standard methods of loudspeakers at home and abroad, because the definitions and interpretations of power are different. Generally, the nominal power of speakers is the rated power

rated power or rated noise power refers to the input power when the loudspeaker can work continuously for a long time without abnormal sound. Generally, the pink noise signal is used for testing within the rated frequency range through a specific filter. According to IEC standard, the tested loudspeaker shall ensure that no abnormality occurs during 100 hours of continuous operation. Incidentally, the American EIA standard stipulates that the test time is 8 hours, and the filter is also different

the maximum noise power is different from the rated power. It indicates the ability of the loudspeaker to withstand large input power for a short time. The test time is only a few seconds or minutes. Generally, the maximum noise power is times the rated power

4) sensitivity

characteristic sensitivity refers to the sound pressure level measured at 1m in the axial direction when the speaker is added with a pink noise signal voltage equivalent to 1W power on the rated impedance. The sensitivity and efficiency of speaker box are two different concepts. Efficiency is the ratio of output sound power to input electric power, but generally speaking, the speaker box with high sensitivity has higher efficiency

the sensitivity of a loudspeaker has no decisive influence on sound reproduction, because people can obtain sufficient volume by adjusting the output of the amplifier. However, in the production of speakers, the sensitivity of speakers is a parameter worthy of attention. Because in a two division or three division speaker, the sensitivity of each speaker unit must be basically the same within the frequency band responsible for playback, so as to balance the high, medium and low tones of the whole speaker during playback. Especially for stereo speakers, the units used in the left and right channels must be strictly screened and matched. It is required that the difference between the output sound pressure levels of the units used in the left and right channels should be within plus or minus 1dB, otherwise it will affect the positioning of the sound image

for professional speakers, especially in long-distance sound reinforcement (such as large halls, sports venues, etc.), speaker sensitivity is also one of the standards that must be paid attention to. This is because to achieve the same sound pressure level, using higher sensitivity can greatly reduce the power capacity of the rate amplifier. Usually, the sensitivity of professional speakers is above 95dB/M.W, even as high as 120dB/M.W. The sensitivity of household speakers is small, and it is very large if it can have 92dB/M.W

5) directivity

directivity is used to describe the ability of speakers to radiate sound waves to all directions of space. It is generally expressed by the curve of sound pressure level changing with the degree of radiation angle to the enterprise. There are usually two ways to express directivity: one is to mark the changes of the frequency response curve at several angles, such as 0 degrees, 30 degrees and 60 degrees, on the frequency response curve of the loudspeaker, and the changes of the sound pressure level can be seen by comparing it with the frequency at 0 degrees. This frequency response curve is called directivity frequency curve. The other is expressed in polar coordinates. It takes the speaker position as the origin and draws the directivity diagram of some frequencies with polar coordinates, from which we can visually see the directivity of some frequencies. In hi fi system, we generally don't want the directivity of speakers (or speakers) to be too sharp (narrow) Otherwise, the audio effect heard by people close to the main shaft of the speaker is better, and the audio effect is worse when they deviate from the main shaft. The scenting range of uniformly hearing the sound of the whole playback band is limited. However, for the venue public address, the directivity of speakers is very important, because the use of directivity can weaken the feedback effect of speakers on microphones, so as to eliminate the roar of the public address system. In professional speakers, there are many other ways to express directivity

the directivity of loudspeaker is related to frequency, and generally there is no obvious directivity at low frequencies (such as below 300Hz). At high frequency, the directivity will become sharp due to the short sound wave length. Therefore, some speakers arrange several high-frequency units in different directions to improve directivity. Directivity is also related to the caliber of the loudspeaker. Generally, when the caliber is large, the directivity is also sharp; Small caliber and wide directivity

6) distortion

the distortion of loudspeaker system includes wipe wave distortion, intermodulation distortion and transient intermodulation distortion. The distortion characteristics of speakers are more likely to cause characteristics deterioration than a single speaker. Usually near the frequency division point, the distortion increases significantly due to improper design or debugging. Harmonic distortion mainly occurs at low frequencies, especially near resonance frequencies. For high fidelity speakers, the minimum harmonic distortion is not more than 2%

when selecting and using speakers, we must not only understand the performance indicators of speakers, but also conduct subjective listening evaluation. In addition, famous brand speakers from famous manufacturers are usually selected. At present, for professional speakers, American speakers are particularly famous, such as JBL, EV, Bose, community (brand C), Peavey, EAW, etc

difference between professional speakers and home speakers

type timbre shape sensitivity power

home speakers have fiber sound quality, clear layers, strong resolution, exquisite beauty, low sensitivity, generally less dB, mostly