【 Weak current College 】 speaker system performance indicators

Speaker system 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, was characteristic of 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 power input 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 characteristics of sensitivity is defined when the 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 diameter large, 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, such as JBL, EV and BOSE, NEXO, RCF, MARTIN, MEYERSOUND, COMMUNITY (CBrand), PEAVEY (Budweiser), EAW, etc. are all famous brand speakers.