和大师对话——声学大师linkwitz对于音箱的一些结论（译文）

lanyuflyin

linkwitz是一个hifi专业领域的的大师，对于追求良好的重放效果一直在追求，推出了好几个作品，他的网站也提供了很多非常有用的知识和测试测量的工具。大师在他的网站上给出了一些结论，出于对hifi事业的爱好，我翻译了其中一部分，遂贴于此，望与坛友们共勉！
   译文采用中英对照方式，有些地方翻译实在拿不准，欢迎拍砖！
听从坛友的意见，分开发，这样容易阅读。一共三个部分，分别是扬声器，开放障板扬声器和箱式扬声器。

  Conclusions . . .
  结论
  

  Sound reproduction in domestic size living spaces has been a life-long interest to me. I have learned much from observation and from my own experimentation. Mostly they confirmed what others already had written about, such as in the many publications of the AES, or the classic texts of Olson and Beranek. But in sound reproduction there are still areas that have not been studied to the point where clear prescriptions or limits can be given as, for example, to sound distribution in acoustically small spaces, or to audibility thresholds for non-linear distortion. I have always been fascinated by the multi-disciplinary approach that has to be taken to the design of loudspeakers, if the goal is higher than another typical consumer product. That approach must include old and new understandings in the fields of mechanics, electronics, acoustics, and psycho-acoustics, as well as extensive experience with test and measurement.

我对在室内空间重放现场空间的声音效果关注很久了。从很多的观测和自己的实验中，我了解了很多东西。其中绝大部分是对于已经出现的资料的确认，比如AES的出版物，以及Olson和Beranek经典论述。但是，在声音重放领域，仍然有些领域没有达到存在清晰确定的规则和限制的水平，比如，在声学小空间上的声音辐射，以及非线性失真的的听觉阀值。我一直着迷于扬声器设计上多学科综合的方法，如果其目标要高于又一个普通的消费产品的话，这种方法将不得不被采用。这种方法包含了新的，和旧有的在机械，电子和声学，以及心理声学领域的知识，同时，包含着测试和测量。

So here are some conclusions that I have come to. I will write them in the form of statements. The background for many of them can be found on the pages of this website. Other conclusions were drawn from observations at CES, dealer show rooms and private listening venues. Many of them are obvious, but I state them since their sonic consequences seem to be underestimated. There are probably more and I might add them as I think of them.

所以，这里有一些结论。我以声明的方式写下他们。许多这些结论的背景可以在网站（指的是作者的网站http://www.linkwitzlab.com）找到。其他一些结论是通过对于CES展览，经销商的展览室，以及私人的听音室的观察得到的。很多是很明显的结论，但是我还要声明这些，因为他们的引起的后果好像被不恰当的估计了。有很多会在想起来的时候加进去。

Loudspeakers
扬声器

    •        The best one can hope for with 2-channel sound reproduction is the illusion of listening into the recording venue. Physics does not allow the accurate reproduction of the original sound field with only two speakers.
     对2声道重放扬声器的最高期望是能够再现录音场地的声像。物理学不允许使用2声道精确重放原始声场。

    •        Since sound reproduction is about creating an illusion it becomes very important to avoid or minimize any clues that would detract from the illusion. Such clues come from linear-distortions, such as frequency and polar response, and from non-linear distortions with their generation of tones and sounds that were not in the original.
     •        既然声音重放的目的是建立声像，那么就要避免或者尽量缩小有损于声像的因素，这些因素来源于线性失真，比如频率和指向性响应，或者来自于非线性失真，比如产生原来没有的声音和音调。

   •        Linear distortion - frequency response, polar response, resonance - affects primarily the timbre and clarity of a loudspeaker.
   •        线性失真-频率响应，指向性响应，共振，主要影响音色和清晰度。

   •        Non-linear distortion - intermodulation, harmonic, clipping - affects primarily the maximum tolerable sound pressure level.
   •        非线性失真-互调，谐波，削波失真，主要影响最大可承受声压。

    •        There is a level of non-linear distortion that is "good enough" relative to other flaws in the loudspeaker. Further reduction of this distortion brings no audible improvement.
    •        相对于扬声器的其他问题，存在一个“足够好”的非线性失真水平，在这个水平上的进一步降低不会带来可以听闻的提高。

    •        For accuracy it is necessary to reproduce sound at near realistic SPL so that the ear generates the correct timbre due to its own distortion. Loudness control or response shaping gives a poor approximation to the Fletcher-Munson curves.
    •        为了精确起见，有必要产生接近于真实的声压，以使得人耳能够因为其自身的失真产生正确的音色。响度控制或者或者响应曲线调整(这里应该是指的频率均衡)只能给出和等响度曲线（Fletcher-Munson curves）很差劲的近似。

    •        I have heard at the AES Convention in 2000 a 6-channel (2 front, 2 elevated side/front, 2 side speakers) Ambisonic microphone recorded (by Chesky) surround demonstration which totally excited me. My listening experiences since then with SACD and DVD-A commercial recordings have left me cold and I happily return to two channels with the ORION.
    •        我曾经在2000念得AES大会上听过6声道的Ambisonic话筒录音系统的环绕声展示，这让我很兴奋。此后，我对于SACD和DVD-A的商业录音的体验心冷了，我又高兴的回归到使用ORION的两声道系统上来。（附上Ambisonic技术的维基连接http://en.wikipedia.org/wiki/Ambisonics）

    •        There are many different loudspeaker designs available commercially. They all change electrical signals into acoustic signals. But if the goal is to reproduce sounds accurately, then a speaker must be either an acoustic point source (monopole, omni-directional) or an acoustically small bi-directional source (dipole). "Small" means that the physical dimensions are small compared to the wavelength being radiated or that the shapes do not interfere with the polar response of the point source.  
    •        有很多不同的商业扬声器产品可以获得。他们都是把电信号转换成声音信号。但是，如果目标是精确的重放声音的话，一个扬声器必须是声学上的点声源（单极点，全向响应），或者是一个声学上小的双向源（偶极）。小指的是物理维度和其辐射的声波相比很小，或者其外形不会和该点声源指向性响应发生干扰。

    •        I have not come to conclusions about a line source that extends floor-to-ceiling, is infinitely long acoustically, and thus generates a cylindrical wave. It seems that this could be an alternate approach to illuminating a room uniformly at all frequencies.
    •        从地板到天花板的线性声源，它在声学上是无限长的，所以会产生柱形波。对于这个我还没有得出结论。看起来这是一个在所有频率上一致的辐射到整个房间的可选的方法。

     •        All accurate speakers will essentially sound the same when listened to in a setup that is appropriate to their specific design.
     •        所有准确的扬声器在为他们而适当设计的设备上听起来是一样的。

     •        Since loudspeakers are listened to in closed spaces there are fundamentally only two ways in which they should illuminate the room sound-wise: Either omni-directionally or uniformly directional over the whole range from low to high frequencies. This allows the delayed, reflected sounds from the room boundaries to have the same spectral signature as the direct sound.
    •        既然扬声器是用来在封闭空间听的，那就只有两种方式能够在房间里给出良好的音乐效果：或者全向的，或者各个方向均匀的，在整个从低频到高频的范围内的声波辐射。这样是因为房间边界的反射声和延迟声和直达声具有相同的分部特征。

    •        The transition in polar radiation from 4 to 2 (baffle step) that is typical for the majority of loudspeakers guarantees non-uniform illumination of the room.
    •        从4 到 2的过渡（障板效应）使得扬声器在房间的各个方向上不会是一致的，大多数扬声器都是这样的。

    •        Reflected sounds are perceptually masked if their initial delay is >6 ms and if the reflections are full spectrum copies of the direct sound. This requires omni-directional or dipole loudspeakers that are free standing in the room.
    •        如果反射声的最初延迟大于6ms，并且和直达声的频率分布是一样的话，从感知上说，会被掩盖掉。这需要全向或者偶极扬声器自由的放置在房间中。

    •        Omni and dipole loudspeakers can sound nearly identical in any given room when properly set up. The room must approach frequency independent reflection-diffusion-absorption behavior above 100 Hz.
    •        全向和偶极扬声器如果适当的设置的话，在任何房间听起来几乎是一样的。房间应该在100hz以上具有频率无关的反射，传播和吸收特性。

    •        Conventional box speakers are always omni-directional at low frequencies and increasingly forward directional at high frequencies and thus the room reflections color the sound.
   •        传统的箱式扬声器在低频率时是全向的扬声器，频率升高时会变成向前指向。所以房间的反射对声音进行了染色。

   •        When designing a loudspeaker it is essential to perform free-space measurements to see the effects of driver directivity and baffle shape on the important polar response. This requires that any reflecting surfaces and objects are at least 10' (3 m) away from the source, that the distance to the microphone is greater than the largest dimension of the baffle, and that the source is rotated around its acoustic center axis. This setup can provide a reflection free 10 ms time record and frequency response data down to 100 Hz. At lower frequencies it is more practical to use boundary measurements, but their integration with the free-space data requires thought and experimental verification.
    •        当设计一个扬声器时，进行自由场测量以观察喇叭的指向性和障板形状对于极性响应的影响是非常重要的。这需要所有的反射面距离声源要大于3m，声源到测试麦克风的距离要大于障板的最大维度值(长宽高中最大的)，声源围绕着声学中心点旋转。这种方法能够得到10ms的不受反射声干扰的数据记录时间，所适应的频率可以低到100hz。在更低的频率时，更为实际的做法是使用边界测量，但是把这个和自由场数据的合成需要通过专业的校正才行。

    •        The 3D free-space response of tweeters and very small loudspeakers can be measured in typical domestic rooms, if the required microphone distance is small compared to the reflection path distances.
   •        如果需要的麦克风(到声源)距离和反射路径距离相比很小的话，高音单元和小扬声器的的三维自由场响应可以在通常的室内进行。

    •        In an active loudspeaker system each driver has its own power amplifier. This gives maximum control over the mechanical motion of each driver and most efficient use of amplifier power. Drivers of different sensitivities (SPL/W/m) are easily combined, while with passive crossovers the driver of lowest sensitivity determines the loudspeaker's overall sensitivity. Amplifier power has to be wasted in the process.
   •        在有源系统中，每一个喇叭都有自己的放大器。这能够对每个单元的机械运动能进行最大的控制，并且最有效的利用放大器的能量。不同灵敏度的单元能很容易的在一起使用，而在使用功率分频时，最低灵敏度的单元决定了扬声器总的灵敏度。放大器的能量被浪费了。

   •        The power amplifiers of an active loudspeaker system see a benign load (resistive, slightly inductive) over their assigned frequency range, unless it includes the mechanical resonance of the driver (highly capacitive and inductive). The single and much larger power amplifier that is required for a passive crossover loudspeaker has to drive a complex load, which places more stringent requirements on its dynamic stability and overall performance. Different amplifiers may sound different.
   •        在所分配的频率范围内，除过将单元的机械共振(很高的容性和感性)计算在内，有源扬声器系统的功率放大器看到的是很容易驱动的负载（电阻性，带有一点电感性）。而在功率分频的时候，则需要一个很大功率的功放来驱动复杂阻抗，这需要放大器有更好的性能和动态稳定性。不同的放大器听起来也不一样。

阿前

机械，电子和声学，以及心理声学领域的知识，同时，包含着测试和测量。
好文，我要学习

hya1951

PLUTO是什么?

老钟头

好贴，楼主费心了。
planar magnetic应是指以Magneppan为代表的磁平面偶极（屏风式）扬声器。

夜未央

•        要把开放障板扬声器搞砸到比你典型的箱式扬声器还难听的地步是不容易的。


冥冥之中真的有轮回

linaux

慢慢看，慢慢消化

飞驰

写得好，翻译的也好！收藏了！

6n9

慢慢消化,慢慢看

lanyuflyin

好贴，楼主费心了。
planar magnetic应是指以Magneppan为代表的磁平面偶极（屏风式）扬声器。
老钟头 发表于 2010-10-31 22:42

嗯，你说的对，谢谢。欢迎拍砖，后面还有一些内容，其中有部分关于房间声学的，翻译好了就放上来。

lanyuflyin

Open baffle loudspeakers
开放障板扬声器

   •        Open baffle speakers are inefficient in terms of the mechanical movement that is required to create a given level of sound. This not only applies to speaker cones but also to panel vibrations.
   •        开放障板扬声器就产生一定水平的声压来说的机械运动方面来说是低效的。这不但对于喇叭，对于面板震动也是如此。

   •        Open baffle loudspeakers reproduce bass with less room interaction. It is more articulate than from box speakers.
   •        开放障板扬声器产生的低音的房间干涉更少，比箱式扬声器更清晰。

   •        If dipole behavior covers the full frequency range, then the room response becomes perceptually masked by the direct sound.
   •        如果偶极扬声器被用在整个频率范围，那么房间的响应将会被从听觉上掩盖。

   •        The radiation from the rear of the cone must not be absorbed, but the distance to the nearest reflecting/diffusing surface should be at least 3' (1 m).
   •        侧面辐射的声波千万不要吸收掉，但是离它最近的反射面和传播表面至少要在1米。
   •        An open baffle circumvents the box problems of delayed radiation through cone and enclosure panels. They occur typically in the mid-frequency range and are difficult to suppress.
   •        开放障板避免了箱式扬声器的通过锥盆和各个面板的延迟辐射。这个问题主要出现在中频并且很难消除。

   •        Large panel radiators or long line radiators suffer from severe lobing at higher frequencies. It manifests in critical room and listener placement.
   •        大型面板或者长线性辐射器在高频会面临分瓣问题。这个问题在关键的房间或者听音者位置上是很清楚的。

   •        Even though a dipole requires a 6 dB/oct boost towards low frequencies, it takes little power to drive it to maximum excursion at its lowest bass frequencies. Amplifier power could be an issue as frequency increases, where it requires higher cone acceleration to reach Xmax. Thus SPL is limited by driver volume displacement at the very lowest frequencies and becomes amplifier limited as frequency increases.
    •        虽然偶极扬声器需要一个6db/oct的低频提升，但是在最低频的时候，它只需要一点能量来驱动它到最大冲程。当频率升高时，功率放大器的能量会成为一个问题。

    •        Realistic bass levels can be obtained from dynamic drivers in open baffles, not from panels. For extreme SPL requirements the number of drivers could get very large and, therefore, below 50 Hz they are more economically replaced by sealed box subwoofers.
    •        真实的低音水平可以通过开放障板上的动态驱动，而不是从面板来获得。对于极端的声压需求，需要的喇叭的数量会很大，所在，在低于50hz的时候，使用闭箱超低音是更经济的。

    •        At frequencies where a 8" driver would become directional it has wider frontal dispersion for an open baffle than if the baffle were closed in the back.
    •        在一个8寸的喇叭变得有指向性的频率上，开放障板有着比从后面封闭的障板更宽的前方扩散。

    •        Open baffle speakers reach deeper into the room and are less subject to the room response if their polar response is well behaved.

    •        如果响应极性能够很好的被运用的话，开放障板扬声器能够更深的到达房间并且更少的受制于房间的响应。

   •        ORION exemplifies open baffle loudspeaker design in terms of polar response control and dynamic range. It circumvents the limitations of large panel radiators and yields a small package.
   •        ORION 在极性响应控制和动态范围方面给出了一个开放障板扬声器的设计的例子。它避免了大面板的辐射问题，并且体积很小。
  
   •        The low masses of the moving parts in an ESL, a planar magnetic, or a ribbon driver are necessary to generate useful sound pressure levels. The force generated by an electrostatic or planar magnetic motor is weak. Since SPL is proportional to air volume acceleration, and moving parts Acceleration is Force divided by Mass, the mass has to be lower if the force is too weak to generate sufficient acceleration. Furthermore, since excursion is limited with these drivers the radiating area has to be large to move a sufficient air volume.. These relationships seem to be difficult to grasp by audiophiles. Marketing departments and even some designers like to tout low mass as an inherent benefit giving greater "speed" or frequency response to their speaker, when it is only affecting sensitivity in SPL/W.
   •        静电，平面磁体，带式扬声器中的气团的移动部分的少量气团是用来产生有用的声压水平所需要的。静电和平面磁体产生的力很小。应为SPL正比于所加速的空气的体积，而移动部分的加速度等于力除以质量，如果力很小的话，质量必须更少。进一步，既然冲程由驱动器限制了，辐射面积就必须很大以推动足够的空气。这个关系比较难于理解。市场部门甚至于一些设计师也喜欢将小质量作为给出更高速度和频率响应而产生的优点来标榜，殊不知这个参数只是在SPL/W影响灵敏度。

   •        It is difficult to screw up an open baffle speaker design to where it sounds worse than your typical box speaker.

   •        要把开放障板扬声器搞砸到比你典型的箱式扬声器还难听的地步是不容易的。

lanyuflyin

Box loudspeakers
箱式扬声器

•        Small boxes have fewer problems with panel resonances, cone re-radiation, and polar response than large boxes.
•        小箱子有更少的面板共振，锥盆再辐射，极性响应问题。

•        Box panels can radiate more sound at certain frequencies than coming from the cone.
•        箱子的面板可能在一些频率上辐射出比锥盆更多的声音。

•        When building boxes from 3/4 inch thick wood, then the un-braced areas should be less than 4 inch squares to obtain high stiffness and to push panel resonances into the kHz region and where they can be decoupled from the driver's structure and airborne vibration.
•        当使用3/4寸的木板制作一个箱子的时候，非支撑的区域的面积要小于4平方英寸以获得足够的刚性并且将面板的共振频率推到上khz的范围，在这个区域的震动能够被驱动器的结构和空气传播解除耦合。

•        The sound behind the driver cone should not come back out through the cone.
•        驱动器锥盆后面的声音不应当通过锥盆再传递回来。

•        Typical box speakers have a generic sound due to their polar response, panel resonances, re-radiation through the cone and vented bass.
•        典型的箱式扬声器由于其极性响应，面板共振，锥盆再辐射，以及开口式的低音具有一般性的声音。

•        Bass from box speakers has more "punch" than from open baffle speakers, but is less airy.
•        箱式扬声器的低音比开放障板扬声器有更多的冲击力，但是缺少空气感。

•        Vented bass speakers are resonant structures and store energy which is released over time. For accuracy, bass must be reproduced from sealed or open baffle speakers that are non-resonant.
•        开口式的低音扬声器是共振结构的，并会储存随着时间推移而释放的能量。为了准确性，低音必须由闭箱或者开放障板扬声器重放，他们是非共振结构的。

•        Closed box speakers are best listened to from very close distance to minimize masking from an uneven room response.
•        闭箱最好从很近的距离聆听以将房间的非平坦响应的掩蔽效应降到最低。

•        PLUTO is not merely another 2-way box speaker. Secondary radiation from enclosure panels and through the driver membrane from inside of the enclosure were eliminated. Being an active speaker, two drivers of very different sensitivities could be combined in order to obtain omni-directional radiation. Bass response was extended by equalization and not by a resonant vent.
•        PLUTO并不仅仅是另一种两路箱式扬声器。箱体和来自于箱内透过振膜的的二次辐射被消除了。作为一种有源扬声器，两个灵敏度差异很大的喇叭可以一起使用以获得全向辐射。低频响应通过均衡器而不是共振开口来获得。（注：PLUTO是linkwitz制作的一款两路扬声器，从结构上来讲类似于闭箱，但是其设计思想和通常的箱式扬声器有很大不同，链接：http://www.linkwitzlab.com/Pluto/intro.htm）

lf00516

先做记号，再慢慢品味品味。

okk

俺认为译得不错。

我来也

做了件好事儿

lanyuflyin

我自己顶，这些结论很有用的，怎么发起讨论的人不多呢？

chene

只有剪下慢慢看了

石头剪子布

好人好事。能够有高人讨论就更好了

kioking

好!!!好资料啊~!!!

hya1951

LZ好事做到底,干脆把http://www.linkwitzlab.com/Pluto/intro.htm）也翻译了,造福大家