【 Weak current College 】 speaker type and performance indicators

Type a, speakers

Speakers of many classification methods, common in professional audio as follows:

1. use the occasion to share: divided into professional speakers and home speakers. Home speakers generally used family playback, it features playback sound quality and smooth soft, beautiful appearance, more refined would, playback sound pressure level is not too high, the bear with a relatively small amount of power. Professional speakers generally used to dance halls would karaoke Hall would cinema halls and stadiums, and so would the professional entertainment venues. General professional sound sensitivity is high, the playback sound pressure is high, the intensity of the good bear power, and household compared to its quality sound too hard, but also not very elegant appearance. But in professional speakers in za, its performance and home speakers more close, exquisite appearance, generally small, so would the za also often been home Hi-Fi sound system.

2. press the playback frequency: can be divided into full-band speakers would sub-woofer and subwoofer. The so-called full-band sound box refers to cover low frequency and high frequency range would-if the audio playback. All the lower frequency bands speakers generally 30Hz-60Hz, ceiling at 15KHz-20KHz. In General, small and medium-sized audio system with only one or two full bands to fully assume the playback sound. Bass speakers and subwoofer is commonly used to add full-band low-frequency and low frequency sound playback of dedicated speaker. The speaker generally used in large-sized audio system would, to enhance the low frequency playback and shock. When used, mostly through an electronic divider (divide the damper) frequency, low frequency signal into a dedicated Bass Amplifier, and promote the bass or subwoofer.

3. Press uses to points: generally can be classified as primary playback speaker. za and back to listen to speakers, etc. Main playback speaker generally used as a main speaker sound system, assume the main playback tasks. Main playback sound performance for the entire sound system's playback quality impact is very large, or you can choose the whole band speakers with subwoofer combination play.

Za for control room, Studio for program monitoring, it has low distortion, wide and flat frequency response, signal very little modification, and other characteristics, therefore most faithfully reproduce the program back to its original state. Back to listen to the speaker also referred to as stage monitor speaker, generally used on the stage or dancing for the actors or members of the band listens to his singing or playing a sound. This is because they are located on the back of the main playback sound box, you cannot hear their own voice or sound of the band's performance, it is not a good fit or find no feeling, severely affect performance. Return to hear speakers into General, slope shape, on the ground, so that both can be placed on the stage before it impacts the overall shape of the stage, but also in playback when a person on the stage, you will not hear the sound back into the microphone and squealing voice.

4. press the to: box structure can be divided into sealed enclosure, inverted phase-speakers, loudspeaker, acoustic labyrinth tube speaker and multiple-cavity resonator speaker, etc. In professional speakers using the most be inverted phase-speaker, which is characterized by wide frequency response, high efficiency, high sound pressure, consistent with the professional sound system speaker, but due to its low efficiency, professional speaker in fewer applications, mainly for household speaker, only a minority of za use a sealed box structure. Sealed box with a simple design and production of debugging, a wide frequency response and low frequency transient characteristics of good, but the dial tone with more demanding of the cell. At present, various speakers, inverted phase-speaker and sealed the proportion accounted for the majority of the speakers, other type of sound, but the structure of the proportion of very small.
Second, the speaker system of performance indicators
1) frequency response (effective frequency range)
This indicator reflects the main speakers working frequency range. When the speakers are constant pressure signal source and low frequency to high frequency by changing the frequency of the signal source, the sound pressure of the speakers will be the frequency of changes. The resulting sound pressure-frequency curve that speaker frequency response curve. IEC (International Electrotechnical Commission) require speakers to replay sound frequency limit, that is a valid frequency range, taking the speakers sound pressure frequency characteristic curve than peak near a multiplier of the average sound pressure level lower 10dB frequency range. This range is wide, the burst feature, the better
General high-fidelity speakers box minimum frequency response is 50-12500HZ (+ 4 ~-8dB), can achieve 50-16000Hz is enough of course 30-20000Hz is better.

2) rated impedance
It refers to the speaker in a specific frequency (MF) in the input-side measured impedance value. Usually that is marked on the product nameplate trademark, given by the manufacturer. Speaker impedance characteristics. The production plant for rated impedance usually rated frequency range should expect a maximum power of impedance mode value. Rated impedance General provisions 4 euro, 8-Europe, 16-, 32-, and also abroad in Europe, with 3 6 Europe, etc.

3) power
Speaker power size is choosing to use one of the key indicators of the speakers. it should be pointed out that domestic and foreign speakers of standard method is very different, this is because the interpretation of the power of definition. General speaker of the nominal power rating.
Rated power or rated noise power refers to the speaker cannot long continuous work without raising an exception when the powerinput of the sound. Generic tests using pink noise signal, through a particular filter, rated frequency range to be tested. According to IEC standards, test your speakers should be guaranteed to 100 hours of continuous work does not generate an exception. By the way, pointed out that the United States standard EIA provides test time of 8 hours, and filters.
Maximum noise power and rated power is different, it indicates that the speaker stand short large input power capacity, its test time of only a few seconds or several minutes. General maximum noise power is the rated power of 2-4 times.

4) sensitivity
Characteristic sensitivity refers to when a speaker plus the equivalent of a rated impedance of 1W power on a pink noise signal voltage, in axial 1m Office measured sound pressure level。 Speaker box of sensitivity and efficiency are two different concepts, efficiency is the output sound power ratio of the input power, but generally high sensitivity of the efficiency of the loudspeaker cabinet is also relatively high.
A speaker's sensitivity level for sound playback is not decisive because people can regulate the output of the amplifier to obtain sufficient volume. However, the speaker, speaker's sensitivity is an important parameter. Because the second frequency or three frequency loudspeaker, speaker unit in the respective responsible for replaying the band, their sensitivity must be basically the same, so that the entire replay sound when the high, mid, bass and balance. In particular, on the left and right channels of a stereo speaker, use of the units must undergo a rigorous screening and matching. Requirements for left and right channels used by the unit's output sound pressure level difference should be within plus or minus 1dB, otherwise affect sound like positioning.
For professional speakers, special sound reinforcement for long-distance (e.g. large halls, sports Jan Museum, etc), sound sensitivity is also the standard must be valued. This is because you want to achieve the same size on the sound pressure level, with higher sensitivity can greatly reduce the rate of amplifier power capacity. Typically, professional sound sensitivity is more than 95dB/m.w, even up to 120dB/m.w. While home speaker sensitivity small, 92dB/m.w even if it is still very large.

5) directivity
Directivity is used to describe the speakers will all acoustic radiation into space direction. It is commonly used for sound pressure level with radiation angle of the curve. Directivity usually has two methods: one is in speaker frequency response curve superscript some perspective as 0 °, 30 °, 60 ° frequency response curve changes through it and 0 degrees when the frequency of sound pressure level changes can be seen. The frequency response curve known as directional frequency of curves. Another way to polar coordinates. It is the location for the origins, the speakers with polar coordinates draw some frequency directivity diagram from which you can graphically see certain frequency directivity. The Hi-Fi system, generally do not want the speakers (or speaker) directivity too sharp (narrow)-otherwise a person close to the speakers spindle hear audio effects, deviate from the spindle is audio effect is worse. Make even hear the entire replay band sound of the inspection scope be limited. But on the venue PA occasions, speaker directivity is very important, because the use of directional microphone reduces speakers on feedback, so you can eliminate whistling sound amplifying system. In professional speakers, nature there are many other representation.
Speaker directivity and frequency, low frequency generally (such as 300Hz) there is no clear direction. High-frequency sound waves, because of the shorter the wavelength, nature becomes acute, therefore some of the speakers are arranged in different directions on a few high-frequency range, to improve the directivity. Directivity also and speaker diameter. General diameterlarge, sharp also directed; diameter is small, the directivity wide.

6) distortion
Speaker system distortion including arrangements wave distortion, intermodulation distortion and transient intermodulation distortion, etc. Speaker of distortion characteristics than a single speaker more easily lead to a deterioration in performance. Usually in the crossover point, due to improper design or debugging, distortion significantly increased. Harmonic distortion usually resulting in low frequency, especially near the resonance frequency. For high-fidelity loudspeakers of minimum requirements for the harmonic distortion is not greater than 2%.
In the selection and use of the speaker, but you must understand the speaker's performance specifications, but also for subjective listening evaluation. In addition, usually choose the famous manufacturers of brand-name speakers. At present, professional speakers, particularly in United States, such as the famous speakers JBL, EV and BOSE, WESLIVECOMMUNITY (C licence), PEAVEY (Budweiser), EAW, etc. are all famous brand speakers.