Performance Comparison

　　性能比较 https://www.hdav.com.cn/play-hometheater/4430.html

超低音箱体指南（z008译）(图1)

　　Sub-30Hz Behavior

转自laowoniu.com

　　30Hz以下的表现

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　　Sealed box designs and single-reflex bandpasses are much better at controlling excursion at extremely low-frequencies (below 30Hz.) For this reason, they can usually handle more power in these frequency ranges than ported designs and dual-reflex bandpass designs which makes them less prone to low-frequency induced speaker damage. At frequencies below the tuning frequency of the port, a woofer in a ported box (or a dual-reflex bandpass) starts to de-couple. This means that the controlling function of the enclosure begins to disappear. The collapse is gradual rather than immediate, but at some point below the tuning of the port, the speaker behaves as if it were operating without an enclosure and suffers from potentially damaging over-excursion. (This is why it is a good practice to use an infrasonic filter when running a ported enclosure or a dual-reflex bandpass. JL Audio "slash series" subwoofer amplifiers offer this feature, as do many good quality active crossovers). 转载请注明出处，www.hdav.com.cn

　　密封箱设计和单反射式带通箱能更好的控制极低频(30Hz以下)范围内单元的行程。 转自老蜗牛家庭影院博客

　　因此，通常在此频率范围它们可以比导向孔设计和双反射带通箱承受更大的功率，这就是为什么后两种设计更少用于会导致喇叭单元损坏的低频范围。在低于导向孔谐振频率的的频段，导向孔箱体(或者双反射带通箱体)内的低音单元开始去耦。意味着箱体的控制功能开始消失。这个崩溃是渐进的而非即刻产生的，但是在导向孔谐振频率以下的某些频点，单元的表现就像箱体不存在一样，并且造成潜在而危险的“过行程”(注：俗称的拍边/碰底)(这就是为什么实际应用中给导向炮或者双反射带通炮加上一个次声滤波器(注：一般滤去20Hz或者以下的低频信号，截止频率由低音炮的参数而定)是一个好方法。JL的“Slash系列”低音炮功放提供此功能，许多高质量的主动分频器也有此功能) 转自laowoniu.com

　　Related to the loss of enclosure damping, ported and dual-reflex bandpass designs also exhibit higher distortion levels at very low frequencies than sealed or single-reflex bandpass designs. The importance of this is questionable, however, since little program material extends to below 30Hz. www.hdav.com.cn

　　从箱体阻尼损失来看，导向孔和双反射带通箱设计在极低频下比密封箱和单反射式带通箱设计有着更大的失真。但是这方面的重要性值得商榷，因为很少有节目素材能够延伸到30Hz以下(注：应该是指的音乐中，而非电影)。 微信号：hdavcomcn

　　Sealed enclosures and single-reflex bandpass designs have a rather shallow low-frequency roll-off rate of around 12dB/octave, whereas ported enclosures and dual-reflex bandpasses typically exhibit 18- 24dB/octave roll-off. For this reason, sealed enclosures and single-reflex bandpass boxes can have much higher -3dB points (the frequency at which the output dips 3dB below the reference efficiency of the speaker) than ported designs while still producing very good ultra-low frequency output.

　　密封箱和单反射式带通箱设计有着更小的低频滚降率，大约是12dB/OCTAVE，反之，导向孔和双反射带通箱代表性的滚降率是18- 24dB/octave。因此，尽管密封箱和单反射式带通箱有着比导向孔设计更高的-3dB频点(输出相对于参考频率下降3dB的频率)，却仍然能够产生很好的极低频输出。

　　30-80Hz Behavior

　　30-80Hz 的表现

　　This is the frequency range that is most important in that it encompasses the vast majority of low-frequency information present in music. Serious audiophiles assign much more importance to good performance in this range than in the extreme low-frequency range.

　　这是一个最重要的频段，其中包含几乎全部的音乐低频信息。严肃的高保真音响爱好者认为这个频段比极低频更能重要，更能决定低音炮的整体表现

　　At moderate power levels all of these enclosure types exhibit pretty decent manners. The ported box and the bandpass designs produce less distortion than the sealed box, but the difference is marginal.

　　在适当的功率下，所有这些箱体类型都有很好的表现。导向孔和双反射带通箱设计比密闭箱的失真更小一些，但是差别不大。

　　At higher power levels things change considerably. The dual-reflex bandpass, due to the fact that its ports control cone motion over a wider range of frequencies, produces the least distortion and exhibits the best power-handling characteristics. The ported enclosure and the single-reflex bandpass also do a very good job producing high-levels of undistorted bass output, again due to reduced cone motion in this frequency range. Bringing up the rear in this category is the sealed enclosure, which produces higher levels of distortion at high power levels. There is a common misconception that ported designs produce more distortion than sealed boxes. As you can see this is not entirely accurate; it depends on the frequency and the power level.

　　在高功率下，情况有了相当大的变化。双反射带通箱，由于它的导向孔在很大的频率范围内控制了锥盆动作，所以产生的失真最小，同时还表现出最好的功率承受特性。导向孔箱体和单反射式带通箱在产生高声压级的不失真低频输出方面也做得很好，这也是由于在这个频率范围内减少了锥盆的运动。排在最后的是密封箱，在高功率的驱动下，产生了相对较高的失真。通常的误解就是导向孔设计要比密闭箱设计产生更多的失真。如你所见，这并不完全正确。这个要取决于频率和功率级别。

　　Transient Response

　　瞬态响应

　　Transient response refers to the ability of the subwoofer system to reproduce quick changes (transients) in the program material accurately. This is often interpreted as "tightness" or "looseness" which is maybe a dangerous terminology since many people are more influenced by tonal characteristics when asked to qualify the "tightness" of the bass. Transient response is actually a function of accuracy in relation to time rather than frequency. In music, sounds like drum strikes and quick bass guitar pulses are good tests of a subwoofer system's transient performance. A system with good transient response will reproduce these sounds with clear, "tight" definition. A system with poor transient response tends to blur these sounds over time, due to the speaker's inability to stop and start quickly enough to react to the signal accurately.

　　瞬态响应是指低音炮系统准确回放节目素材中的快速变化(瞬态)的能力。这个指标经常被认为是“紧致”或者“松散”，这些可能成为危险的词汇。原因在于当人们被要求去界定低频的“紧致”时，更多的是被音调特性(注：应该指的是声音随着频率不同所表现出来的不同特性，频率越低听起来越松散，越高越紧致，这将会影响听感)所影响。瞬态响应其实是精确度与时间的函数，而不是频率的函数。在音乐中，类似于鼓声和低音吉他的快速冲击是对于低音炮系统的瞬态响应的很好测试。瞬态响应良好的系统能够清晰而“紧凑”的回放这些声音。瞬态响应差的系统往往在时间上把这些声音弄的模糊不清，因为喇叭没有能力停止和开始得足够快来准确的重现这些信号。

　　It is generally accepted that an optimized sealed enclosure exhibits the best transient response characteristics. The control provided by the air-spring in a good sealed system contribute to generally outstanding transient behavior (at very high power levels, the increased distortion can overshadow this advantage, however.)

　　通常人们接受的说法是最优化的密闭箱能表现出最好的瞬态反应特性。在良好的密封箱系统中，空气弹簧提供的控制能力通常会对优秀的瞬态反应做出贡献(然而在高功率驱动下，增加的失真会使掩盖这个优势)

　　A ported enclosure can also achieve good transient behavior but never as good as an optimized sealed enclosure. It is possible, however, for a well-designed ported enclosure to have better transient response characteristics than sealed enclosures with higher Qtc's (above 1.0.) The specific alignment of the sealed and ported enclosures plays a huge role in determining the transient characteristics of each individual subwoofer system.

　　一个导向孔箱体也能够实现好的瞬态表现，但是永远不可能赶上最优化的密闭箱体。然而一个设计良好的导向孔箱体能够比高Qtc值(大于1.0)的密闭箱体有更好的瞬态响应特性。对于密闭和导向箱体的特定调校，将会对每每个单独的低音炮系统的瞬态特性产生巨大的影响。

　　Single-Reflex bandpass designs can also have good transient characteristics if their bandwidth is fairly narrow, but again, not as good as an optimized sealed enclosure. As the bandwidth becomes wider, their transient response can degrade considerably.带宽相当窄的单反射式带通箱也有能够拥有好的瞬态特性，但是再次强调，不可能赶上最优化的密闭箱体。当带宽越来越宽的时候，瞬态响应也会有相当大的下降。

　　Dual-Reflex designs generally exhibit inferior transient response characteristics when compared to the other designs. As with single-reflex designs, narrower bandwidths produce better transient performance than wider ones.

　　双反射式带通箱一般所表现出的瞬态响应特性比其余的设计都要差。就像单反射设计一样，窄带宽比宽带宽的瞬态表现更好。

　　Efficiency

　　效率

　　The term "efficiency" refers to the ability of a speaker system to convert electrical energy (power from the amplifier) into acoustic output. Consequently, it also serves as an indication of which system will produce the loudest possible output given the same size amplifier (assuming they can all handle the power.) For the purposes of this comparison, we are looking at efficiency in the 40-80Hz octave.

　　术语“效率”是指扬声器系统将电能(功放的推力)转化为声音输出的能力。因此，这个词也作为一个指标，来表示哪个系统能够在功放大小相同(假设系统能够承受这个推力)的情况下，产生最高可能输出。

　　Generally speaking, the most efficient enclosures are the two narrow-bandwidth bandpass designs with the dual-reflex version having a slight edge. Next in line, the wide-bandwidth dual-reflex and the ported enclosure exhibit very good efficiency as well. The sealed enclosure and the wide-bandwidth single-reflex bandpass are the least efficient designs.

　　通常来说，效率最高的箱体是两种窄带宽的带通箱设计，其中双反射版本会有小小的优势。接下来，宽带双反射带通和导向孔箱体也有很好的效率。密闭箱和宽带单反射带通是效率最差的设计。

　　Midbass transition

　　中低频(注：80-160Hz?)过渡

　　For sub-bass to sound natural, the system must have good midbass capability as well. These two are interrelated because harmonic components of the sounds produced by instruments that play in the sub-bass range must be accurately reproduced in the mid-bass range for a system to sound accurate.

　　为了使低频能够听起来自然，系统必须还要有良好的中低频能力。这两个频段是互相关联的，原因在于乐器产生的低频段的声音，其谐音部分必须能够在中低频范围内被精确还原，这样的系统听起来才够精确。

　　In car audio, we normally don't have the luxury of using very large drivers to reproduce midbass. For this reason, the ability of a subwoofer system to smoothly transition to the mid-bass region becomes very important to achieving top-notch fidelity.

　　在汽车音响中，通常我们不能够奢侈地使用很大的单元去产生中低频。因此，低音炮系统平滑过渡到中低音区域的能力对于实现顶级的高保真至关重要。

　　The sealed and ported enclosures, because the speakers play directly into the listening environment usually produce the smoothest midbass transition. Wide bandwidth bandpass designs are a little more ragged, but still deliver good midbass reinforcement. The narrow bandwidth bandpass designs can create serious problems because their high-frequency roll-off can begin as low as 75-80 Hz and the amplitude of their response peaks is very high, which necessitates the use of larger, very capable midbass speakers in order to blend smoothly with the sub-bass.

　　密闭和导向孔箱体，由于扬声器直接在听音环境中播放，一般都会产生最平滑的中低频过渡。宽带带通箱设计的过渡会有些粗糙，但还是能带来好的中低频强化。窄带带通箱设计会造成严重问题，因为他们的高频滚降开始的频率会低到75-80Hz，并且频响曲线的峰值非常高，使你不得不用大而有力中低频扬声器来衔接极低频，使之过渡平滑。

　　There Is No Free Lunch

　　天下没有免费的午餐

　　As you can see by the comparison, no enclosure design is superior in all respects. They all have advantages and disadvantages. Analyzing the characteristics of each enclosure type will help you decide which enclosure type is right for your application. An informed decision involves an analysis of the following factors: the space that you want to make available in your car for the enclosure, your performance expectations (loudness, tonal qualities, etc,) the amount of amplifier power you will be using, and of course, your budget. Top-notch car audio specialists will weigh all the factors and consider all enclosure types before recommending a subwoofer system. Many will even show you specific data to support their suggestions.

　　通过比较你可以看到，没有一种箱体设计是万能的，它们都有优点和缺点。通过分析每一种箱体类型的特性，能够帮助你决定你的应用环境需要哪个类型的箱体。一个深思熟虑的决定包括如下因素的分析：你想在你的车里腾出多大的空间摆放箱体，你的性能期望(响度，音质，等)，你使用的功放功率，当然，还有你的预算。顶级的汽车音响专家会权衡所有的因素，随后才给推荐低音炮系统给你。很多甚至还会给你看特性数据来支持他们的建议。

　　Remember that the information presented here assumes that each enclosure type has been properly designed and executed. This means that the speaker and the enclosure are carefully matched as a system. The skills of a competent designer, installer and cabinet builder are every bit as important to the end result as the design of the box or the type of woofers that you buy.

　　牢记这里所有的信息都是在每种箱体类型都经过适当设计和施工的前提下。就是说单元和箱体被细心配对为一个系统。合格的设计师，组装工和箱体制造者的技能熟练度，和箱体设计或者你购买的单元类型，对最终结果都有相同的重要度。

　　Despite the very general scope of this piece, we hope it leaves you with a better understanding of subwoofer systems. At the very least, we hope that the next time you hear someone say "whatever you do, don't port the box" or "sealed boxes don't sound good," you will ask them to thoroughly explain their position. It could be amusing.

　　撇开这篇文章里的基本常识，希望能够带给你一个对于低音炮系统的更好的认识。有一点就是，希望下次听到有些人说：“随便你选什么，都不要选导向箱”或者“密闭箱听起来不好”，你会要求他们彻底解释下这个看法从何而来，这将是一件很有趣的事情!

　　原文在这里，虽然是针对汽车音响的，但是有许多东西是共通的：http://mobile.jlaudio.com/support_pages.php?page_id=147