Weak current College】 【how to angle from technology and applications to determine the merits of sound (go)-Power By】 【China power house network.

<br> <br> In the entire audio (including PC multimedia speaker system) system, the speaker as a sound system of replay tool that is seemingly the most simple, but for the most complex equipment. Because it is responsible for the mechanical and .electrical transforming equipment, playback effects directly related to the quality of the entire system, so the speaker selection is done right, is a sound system can match, an important factor of success. To determine the merits of a pair of speakers, usually from specification .and the subjective listening on these two aspects, the author of this article describes the intermediate to simple for our friends in the formation of his own sound system. <br> <br> A Hi-Fi speaker's main, specification <br> <br .> International Electrotechnical Commission (IEC) on the home Hi-Fi speakers have of a set of minimum standards, the standard file encoded as IEC-581-7, as long as the specification from the speaker in a look at its technical parameters meets this .minimum standard, it can be more objectively determine whether qualified speakers. IEC-581-7 on home Hi-Fi speakers of some minimum standards are: <br> <br> (1) frequency characteristics: 50Hz-12500Hz, deviation in + 4 .~ 8dB; in 100Hz ~ 8kHz band, the deviation of ≤ ± 4dB; <br> <br> (2) links to features: horizontal ± 30? o, vertical ± 10? o, frequency response curve compared with positive axis deviation ≤ .± 4dB; <br> <br> (3) left and right speakers of inconsistency: 250Hz ~ 1kHz within the scope of the difference between the average sound pressure; ≥ 2dB <br> <br> (4) total harmonic distortion: 250Hz .~ 1kHz, ≤ 2%, 1Hz ~ 2kHz, ≤ 1% -2%, 2kHz ~ 6.3kHz, ≤ 1%; <br> <br> (5) impedance: 20Hz ~ 20kHz, ≥ 80% of the rated impedance; .<br> <br> (6) allows the use of power: 10W. <br> <br> From the above these standards we can see clearly that conform to the standards of IECHi-Fi (fax) the technical requirements of the speaker .is not very high, now available in the market by a formal manufacturer speakers can basically meet or exceed these standards. So in this large number of qualified products, how to go from specification to determine whether a pair of speakers for excellent? author believes speaker .is excellent? author believes the most important thing is to look at sound frequency response range, point to properties, sensitivity, power and impedance it suffered several indicators. <br> <br> Frequency response range refers to the speaker to replay sound frequency range ., Hz-kHz for general use. Since the human ear on the limits of the frequency audible range 20Hz ~ 20kHz, with age, the listening ear drops to around 25Hz ~ 16kHz. Therefore, as a pair of excellent speakers, its frequency response range .of course must meet or exceed this range. <br> <br> Point to properties indicate the speaker off when on the front axle to output sound pressure level of the changes it on sound field width and positioning has a great effect. But speakers ( .mainly refers to the high frequency range) is not the nature of the wider the better, professional product you have certain requirements, well-designed unit (mainly, drum) directivity control the scope of the provision, and the sound pressure level decline less than .6dB. General ball and cone cells you can not do it, they increase the frequency directivity and gradually narrowing. To point to a character meets the demands, on request of the unit is: If the deviation is reached in the axial direction of 30? .o does not decrease when compared on a 4dB,-n frequency f and the radius of a cone loudspeaker with equivalent to meet between f ≤ 140 / a, such as the diameter of 200mm (8 inch) speakers of crossover point must be in 1650 .. Of course, some design advanced sophisticated driver you can also set the crossover point than the theoretical values higher, but whether it is low, medium and high frequency speakers, in the options response caliber, crossover points, the power to consider this point ( .two crossover especially important), many second frequency speaker only fractional frequency taking into consideration the treble speakers and power capacity will get very high color separation point, ignore the nature of the request, such systems are often only in the speaker positive axial has good of .frequency response, and the deviation from the axis, frequency response, affect the sound field of width and positioning. <br> <br> Sensitivity refers to the speaker audio conversion efficiency, usually sound pressure dB / W / m or dB (decibels) .to indicate that the meaning of this indicator is pointing to the speaker input 1 watt of power, the left speaker 1 m as the axis of the size of the sound pressure. Hi-Fi replay requirements for maximum reach 110dB of output sound pressure, this .requires the speakers will have a higher sensitivity and some of the best power margin, so that larger than 88dB at least two benefits: first: on the amplifier and speaker of the lower power capacity requirements, while reducing both costs (on sensitivity to achieve output .of 88dB 110dB sound pressure level, to have the input power of 160W, and sensitivity to each increase 3dB 110dB sound pressure level required power to decline a times); second: you can reduce the distortion. Low sensitivity to achieve the same with high sensitivity .and output sound pressure level, more power and amplitude, but this will increase along with nonlinear distortion, and the life of the speakers will be reduced. On the other hand, a better speaker sensitivity is more than when they 86dB and rated output power amplifier .with only 50W or anything, but not the sensitivity of the speakers are not good, like foreign some classic Hi-End speaker, where LS3/5A and ATCSCM-20, sensitivity are lower than 85dB. Therefore, for the purposes of this indicator is ., of course, the bigger the better. Because of the high sensitivity of the speakers in the same power in cases of sound pressure sensitivity of lower than the speakers, on the contrary, in the same sound pressure, the amplifier's power requirements than sensitivity small .low speakers. Therefore, sensitivity is a pair of speakers is evaluated to promote important technical indicators. <br> <br> Bear power refers to the speaker can bear does not lead to undue distortion of power. If you enter more than the speaker continuously .ratedPower (RNS), the speaker will not only be distorted, and the danger of being destroyed. Therefore this indicator is, the larger the better, but in a real application, 100W RMS reaches the speakers the opportunity to have burnt down to zero, .because has not reached this target before the ear has bear its sound pressure. In the multiple frequency loudspeaker, easy burnt also greatly reduced. Therefore, when choosing speakers, in addition to speakers of power, but also pay attention to what eschew the use of .materials and manufacturing. <br> <br> Impedance is a speaker on AC resistance, resistance, capacitance and inductance, resistance to three parts is the calculation of the amplifier supply power benchmark values. Since the speaker impedance is as the frequency of changes, .so the manufacturers to speaker mark value is actually a mean value. This is used when the sound is to note that common household speaker impedance 8 ohms, there are usually 6 ohms and a 4-ohm.? the impedance of the modern speakers have a .tendency to small development, speaker impedance reduces the size of its advantages is that you can get from the amplifier to more energy, that is to say, in the enter the same power and sensitivity, more or less large, impedance small speaker sound than the .impedance large speakers sound great. when using a pair of speakers and supporting the use of an amplifier, a matching problems very small (especially the transistor machine). But when one amplifier driving two pairs of speakers, will be taken to avoid two speaker impedance .inconsistent (such as a pair of 8 ohms, 4 ohms) and two pairs of speaker impedance 4 ohm in the following, otherwise, it is easy to approximate short-circuit Burnout resulting amplifier. as regards the consistency of the left and right channels, .there is very little on the specification annotations. From experience, the most common product does not meet this requirement, but the indicators on the sound field and sound like the exact reproduction of the position. We buy, the best is to buy some reputable brand .products, preferably left and right channels by matching products, generally this product in the speaker's production numbers are specified. <br> <br> 2. subjective (listening to interested) on the evaluation <br> <br> To judge the quality of .a pair of speakers, although from specification to be sure of the answer, but people buy speakers or other audio equipment just to get a good sound rather insipid specification, there are better spec does not equal good sound, as the beginning of the CD there ., no one can deny it on the specification extends far beyond LP sing up. But because the early CD machine exists sound dry and hard, sharp, no music taste drawbacks, it brings a lot of people. In the case of the speaker, the .existence of such problems, such as the famous LS3/5A, its sensitivity only 82dB, impedance as high as 11 ohm, specification, it is a pair of very low efficiency of the speaker, but it is the most famous in the history of za ., because it is the human voice and strings have Excellences, therefore it was widely welcomed. From the above example we can see that the evaluation of the sound equipment, by relying on specification to judge its quality is one-sided, plus the audio sound .preferences, so buying speakers, especially some of the early conclusion of excellent products, listening to interested can make on their own meet seems to have become more important. <br> <br> Comments on the subjective listening to the sound of an important aspect .which is able to reproduce the original sound of accuracy. Accuracy of strictly defined is within a certain price and speaker size constraints, should as far as possible, wide frequency bands can reproduce original sound recording sound details, dynamic range and surrounded by interested, even .if there are differences should be minimal. <br> <br> In order to ensure the accuracy of listening to comment, you must seize every opportunity to listen and to compare different sound-reproducing differences, at the same time as adoption of high- .quality amplifier and high level of sound source equipment, different speakers in the same volume, the same set-up auditory assessment so as to reduce the number of listen to comment on the change factors. As a result of the use of the software subject to .hear comments on the results of the impact is very large, in the select a music recording, should not only focus on the music itself how sweetly, while also paying attention to their recording accuracy and to highlight the sound quality of certain requirements. <br .> <br> Subjective listening on time can be summarized in the following four broad criteria: <br> <br> 1, timbre uniformity <br> <br> Listen to the sound timbre uniformity is the most important in the assessment. Speakers in .the bass to treble in the whole frequency range should be uniform and real sound performance. On the whole range of overall assessment, a four-paragraph in General: <br> <br> A. bass / bass range of irregularities. The best description .of the problem is that there are no bass performance hum or weak, or have no hair dull sound of empty. <br> <br> B. vocal range of fluency. The human voice speech voice and included an actor's voice, to comment on .whether there is a noticeable phenomenon of if staining. This is easier to have the tight sound of weaknesses, performance is not constant tone, sound quality is poor, sound with serious nasal, hum or rough harsh sound, empty sound, etc. <br .> <br> C. the treble range (2500Hz ~ 13kHz left band) fluency. You should choose the large orchestral Zhu team string portion of the hearing, that there are no strings sound unnatural or sound dry or too viscous paste in place. To .do this band nominated staff quality correctly requires a relatively high, but also on the scene some string performance with a very skillful capacity to appreciate, it is best to please some experienced shaoyou help. <br> <br> D. Special treble zone ( .13kHz above band). Note to listen to jazz or rock and roll vocal effect of Eastern, Central and pull-out test of CD drives, and should contain clear and repeated playing of transient part aware should listen carefully to each speaker's expression is ambiguous character ., Brazilian-sound and a rustle rather clear metal sound, which represents a special treble zone of timbre uneven surface defects exist. <br> <br> 2. dynamic range <br> <br> Almost all speakers will make the sources of dynamic .range is compressed. Dynamic range fromRestrictions of clear-type is generated can be heard out of distortion, if the frequency is not balanced, high-frequency out of line, etc. Usually the bass and baritone hums, Brazilian-sound or too loud popping .. Dynamic range of another kind of hard to find in a restricted form of nonlinear response, manifested in the great volume of driving, part than in treble bass part to send out than low frequency output of larger volume, resulting in strong, broad-band .of the moment of impact. Because bass unit issue rumbles, not sure is speaker distortion or furniture, floors or Windows caused by vibration, likewise not sure sound enhanced phenomenon is caused by the speaker, or ear at very high volume of naturally occurring distortion, .this points to the familiar listening environment for a longer period of time, repeatedly. <br> <br> 3, bass extension capabilities <br> <br> Very few speakers can reproduce low da real 20Hz or 25Hz frequency, recording the content of .the energy is concentrated in the following band also 40Hz is very rare. With classical music in the big bass drum and popular music in bass synthesizer bass extension ability to judge the best signal source. But, if not at home in the actual environment listen, .it is difficult to determine the speaker's ultra low audio should be ability. Because the speaker's display and Interior acoustic characteristics of sound box bass performance impact than on effect of sound itself.? taking into account the above, the available period or for several very familiar .with the content of the recording on the speaker's bass extension capabilities for hearing assessment, content should contain a considerable dynamic range of percussion instruments, an easy feeling of subwoofer recording music judge speaker of low frequency sound performance. <br> <br> 4, .sound like positioning capability <br> <br> Sound like positioning refers to sound in the space arena location and depth of sound, like the ability to listen to the commentary on positioned box is the maximum variation is also the most difficult to master for an .index. <br> <br> Listen to commentary on locust, it should be noted that sound like the positioning of stability. For example, the band is an actor's position as the musical frequency raise or lower the drift and volatility. Sound stage is .filled with two speakers between or beyond the speaker distance between whether to extend the sides can only be guaranteed in buildings in the middle of the two speakers? musical instrument and vocal parts around the depth is naturally expand? is there too much exaggerated reverb phenomenon? .<br> <br> Different types of speakers for the inherent characteristics of sound like positioning. For example, dipole-and most of the static type and graphic design of loudspeaker pole type typically create enhanced depth and space at the expense of an ordinary speaker .; between the two.? understanding after listening to the commentary on the points mentioned above, should also be aware that different countries and regions of the speaker, and also due to the influence of local cultural factors and exhibit different sound characteristics. Theoretically, a .design the ideal speaker should be suitable for all genres of music, faithfully replay true Vocality, signal components do not increase or decrease, but really can do neutral sound speakers. While in theory that speaker frequency response curve, the more flat getting better, but .in fact a frequency response of flat speaker sound not necessarily beautiful, most speakers are some band curve gently, different sound curves are different, this is also a sound style. <br> <br> Such as the United States production of speakers generally has .a lively, bold and bright sound characteristics, United States sound is divided into East Coast sound and the sound of two on the West Coast, East Coast sound of representative is AR, THIEL, AVALON, Hales, Cello and Boston, and other brands, .the speaker generally more focused on the exact reproduction of the sound, a more suitable to play traditional music tendencies, and be able to create a deep, broad sound field, and the overall sound and the sound is somewhat similar to the United Kingdom, but .sounds more dynamic drive, analysis of force more powerful, these brand has become the new representative of the United States speakers. The JBL and Alter and other production of speakers is the representative of the West Coast sound, Hollywood, this speaker sound particularly bright, .bright, particularly strong, listen to often can have a strong sense of functional stimulation, whose sales are those like rock, jazz and pop music, in recent years on the West Coast sound of voices have snaps to the East Coast. ... the vast majority .of the United Kingdom has sound equipment generally sweet, warm, bass and rich music taste characteristics, it should be said that this is a very suitable for use to listen to the sound of classical music. As the United Kingdom's speaker mostly follow the BBC's standard .manufacturing, quality and more assured. In addition, small bookcase-speaker is also very good at United Kingdom of a product, a representative is ProAc, Rogers, ATC, AE, KEF, B & W, Tannoy, Mission, and other famous .brands.? over the past two years the European sound was ridiculed "Charme", European sound can be divided into two Nordic and southern Europe, Northern Europe, most of the products subject to the influence of France products, voice gives out a unique fresh .France were beautifully romantic, while in the characterization of the musical details also has its peculiarities, compare the representative brand LMLab, Dali, etc. Southern European products to Italy as representative, the sound is characterized by the amount of enthusiasm has charm, with adequate .representative products are famous Sonusfaber, Germany, Sweden and Denmark's speakers you have a straight, bass less sound characteristics, representative products has Jamo Dynaudio, etc. <br> <br> Early Japan speakers tend to follow the United States West Coast products, much .to emphasize the high contrast, low frequency sounds will find it very early, but long time listening to easily make people feel tired. As Japan speakers manufacturing technology continues to progress and the world sound market pattern changes, now Japan small and medium-sized speakers .like victories (Victor), JVC's SX-V1, SX-V7, pioneer of the DS-A5 Diatone S-LH5 and at the cost performance is good, the sound gradually to the high-analysis, energy is abundant and accurate reproduction of the .sound characteristics of the direction of change. <br> <br>.