Application of technical characteristics of loudspeaker

The speaker system has a number of features that are directly related to the use of sound effects and the use of the occasion. In order to make good use of these technical characteristics, users must be aware of them.

1） Two way and three speaker system

Audio signal spectrum range is very wide, to the 20Hz-20KHz signal with a loudspeaker unit is unable to meet the whole section of the frequency response; general more than 12 inch large-diameter speaker unit, bass response is very good, little distortion, but more than 1.5khz signal, it is sent; 1-2 inches tweeter unit (treble compressed drive) replay 3kHz above the signal performance is very good, but cannot replay the tenor and bass signal. And then there are the speaker system composed of various frequency response characteristics of the unit, by bass (bass) and Soprano (ALT) composed of two units called Lu Er speaker system, composed of bass, midrange and treble three unit known for three road system.

Two way loudspeaker system structure is simple, the cost is relatively low, in order to solve the lack of the midrange frequencies, so some manufacturers used a bending failure method, namely in the crossover network to the frequency response of the woofer to move on, the treble unit remains to be seen whether the frequency characteristics is moving downward. Another problem is that the frequency crossover frequency can be set between the 500Hz-2kHz. And this area is an important part of the spectrum of vocal and music. So in the sense of hearing people left "empty" feeling and heard the distortion. Also because of this, the three speaker on the speaker unit requirements are relatively high, if the unit is not good, the entire speaker system is not smooth enough sound, or a serious phase distortion.

Of each unit of the three-way speaker system characteristics without compromise, give full play to their respective strengths, the two frequency cross points are optional in the alto voice and music spectrum is an important part of, at the lower edge, the sound without any influence, so three-way speaker system reduces the distortion of sound, so as to improve the clarity of sound, improved between low and high treble cross band performance, increase the loudspeaker system power handling capability, and therefore is best choice for theatrical performances, concert halls and opera houses of sound reinforcement system.

2） Sensitivity and maximum sound pressure level（SPL max）

Speaker unit is between an electrical signal and sound transducer, and demands that it with a relatively small input power convey replaced with a loud voice, this requires that the speaker has a higher sound pressure sensitivity, sensitivity [] is essentially is a conversion efficiency of embodied, all kinds of Yang loss of paramagnetic systems because the technology to design, selection of materials and production processes and other aspects of difference, a large difference in sensitivity.

Sensitivity refers to the input speaker unit 1 watts of electrical power, in the direction of the speaker axis 1 meters away from the sound pressure level, if the sensitivity of the two speakers to reach the same large sound pressure level output, need to increase the power of the input power, so the higher the sensitivity of the speaker can emit a loud sound.

The input power capacity of the speaker system is generally far greater than 1 watts (usually between 100 watts -2000) so the actual use can be entered into this maximum allowable power, with the maximum power, input speakers, the sound pressure level of the speaker's axial 1 meters is called the maximum sound pressure level Max SPL case, the sensitivity =100dB, 1w/1m speakers, if the maximum power of 1000W SPL, max=100dB+30dB=130dB 1m.

3）Distortion and sound quality

Speaker factories are not the nominal products they rate distortion, in fact, it is a very important technology parameter, and the sound quality is a more abstract evaluation, nor may the document nominal, can only take subjective listening competition. Usually, sensitivity and sound quality is contradictory, the producers need to make a proper balance between the two, generally speaking, low-cost products, sensitivity to play the leading role, the pursuit of performance to price ratio, and high priced products stresses quality, and at the top of the hierarchy is both.

4）[personality] and [common]

This again leads a relatively abstract and subjective performance evaluation, sound with sound, is different from the home Hi-Fi audio equipment, compatibility must be very high, because each site may show different types of programs, from opera to rock concerts, may also only is the language signal mainly report therefore, the sound system must be compatible with the different source of the program, do [average] excellent is not focused on a certain purpose, and the home Hi-Fi audio equipment, just need to take care of a person or a small group of people's taste, the product is a [] allowed to exist, but as a professional sound system is this equipment, individuality will become [limitations] or [defects].

Need for professional sound reinforcement equipment for a large group of public service, program content often transform. [common] is the basic requirements, stronger compatibility, the different nature of the program to [mean], in addition, the professional sound reinforcement equipment must be "rendering", "is not an exaggeration" and "faithful" to the reproduction of the source material that [common] or [common].

5）Pointing characteristics of speaker system

The sound of the loudspeaker is usually in the low frequency range (below 200Hz). The sound is transmitted in different directions, but in high frequency range, the sound is transmitted in a strong direction, which is used in the system design.

Pointing to the characteristics of the speaker to the sound pressure level away from the axis with the angle increases and the sound pressure level decreases gradually, while the sound pressure level increased with the increase of the propagation distance and sound wave according to the inverse square of the distance and distance attenuation, distance and azimuth in the speakers of different audiences, if these two attenuation can make the right choices, two the attenuation compensate each other, so that the sound field is more uniform, large projects need to cover relatively broad area, the only sound is usually not sufficient to cope with the multiple speakers together speakers group (Chen Lie) in Chen Lie, speaker system, constant directivity can make the acoustic sound between middle and high frequency interference not in the box, with a pair of speakers with the directional characteristics of composition of eight shaped display, as can cover a single speaker or speaker sound in front have each other Phase interference, which seriously affects the uniformity of sound field and the clarity of sound.

6）Power handling capability of speaker system

The speaker's power handling capability is an important technical parameter, which represents the speaker's ability to withstand long-term continuous safety work, understand the speaker's power handling capability. First, we must understand how the speaker driver is bad, and the driver's damage mode has two kinds:

One is the voice coil overheating damage (voice coil burned, over heat distortion, the ring breakdown, etc.), and the other is the drive of the diaphragm displacement exceeds the limit value, so that the speaker's conical diaphragm / or its surrounding elastic parts damage, usually occurs in the low frequency signal contains many large amplitude.

Sound signal is a sine wave signal, but a random, these random signals available three to numbers, effective value (RMS) also known as root mean square value, is to a measurement result of signal peak amplitude of the sinusoidal signal, which is close to the average value, basically representative of the signals of the heating energy.

The peak value (Peak) is the maximum signal level, the peak level is greater than 3dB, for the music signal, the peak value is important, the peak value is 6dB, the peak value is 4 times the effective value of AES2-1984.

The speaker power handling capability is measured the technical parameters according to pink noise signal (AES2-11984) treatment for 2 hours after permanent changes in the electrical and mechanical performances of not more than 10%.

7）The sound pressure drop (also called power compression) after loading (heating).

All product specifications on the nominal power are the manufacturers own, is the best value in the selected speaker test signals and conditions, when the speaker into the work of the state (for example after the full power is equal to or greater than 20 seconds), the heating temperature of voice coil and magnet, because they can drop to change the original characteristics the heating unit before the actual sound pressure output will decrease, conventional speakers, such as voice coil temperature rise of 60 degrees -80 degrees, common rated sound pressure level decreased 3dB for tolerance, such as voice coil cooling is excellent, temperature of 100 degrees Celsius, the actual pressure drop can reach 6 to 8dB, which is quite alarming decline the above questions and doubled the speaker only ascend 3dB SPL if the speaker sound pressure level decreased up to 6dB, to compensate for the sound pressure level of such a big drop from a speaker must be increased to four, very sorry, sound engineering The industry does not have a nominal sound pressure level, must be better to improve the thermal design of speaker unit.

8）Impedance of speaker unit

The impedance of the speaker unit includes, inductance, capacitance and resistance, inductance and capacitance are varied with frequency, although the nominal impedance of the speaker system is too large to affect the stability of the whole sound system. The new DCD JBL dual line differential drive is designed to make the whole sound system stable.