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【HAA声学知识】调试低音炮不仅是音量大小
Calibrating a Sub Means More Than Adjusting the Volume
低音炮的调试仅仅就是音量的调大调小么？
I sometimes joke in my classes that many consumers very carefully adjust sub level by incrementally turning it up bit by bit until, the exact moment, it won’t play any louder. In those cases they get what they are asking for; pant-leg moving bass pulsating through the room for explosions and heavy metal music. Meanwhile, the more subtlety oriented folks in the room (commonly the consumer’s wife) flee from the carnage swearing to never return. The final chapter in such a saga often includes a slow emotional withdrawal from the theater after the realization that “High End” bass just isn’t as cool as they thought. This intro begs the question, “What does calibrating a sub really mean?”
有时我会在HAA的培训课堂上面打趣说，许多客户会非常认真地调试他们的低音炮，他们会非常仔细地一点一点地将音量调大，直到再也不能继续调大为止。
在这类案例当中他们也发现了问题：每当播放到爆炸声和重金属音乐时，有规律的低音都会穿透房间引发震动。同时，房间里原本惬意的人们（通常都会是该客户的妻子）都会因为受不了如此的折磨飞快逃离并且发誓再也不踏进此房间。
在诸如此类“传说”的最终篇章总是以不愉快收场。我们这位富有激情的客户会缓慢地经历这样的情感纠结：或许这样“高端”的超低音扬声器并非自己想象当中的那么酷。由此而产生如下问题：“低音炮调试到底真正意味着什么？”
(找炮位是个费时费力的苦差事，但依然有人乐此不疲)
A better question to ask is, “What does a well calibrated sub sound like?” How do you know a sub is tuned in versus not. This question is raised to a new level given the rapid improvement in technology available to the consumer over recent years. The advent of equalizers and sophisticated measurement gear has released the calibration of home sound systems to a new state of the art. Gone are the subjective notions of tuning sub location by ear and guessing at the frequency of booms by playing your favorite pipe organ tunes. Mind you, I am still committed to the role of critical listening in the calibration of systems, but only as a performance check. Critical listening tells us if we succeeded but is not as efficient for diagnosing the cure for problems as making measurements.
这个疑问或许这样来问更好：“一只经过成功调试的超低音扬声器听起来到底是什么样的？你如何得知这台超低音是经过调试的还是没有？”随着近几年来科技的进步，客户对于这个疑问也已经提高到一个新的级别。均衡器和精细测量设备的出现推动了家庭声学系统调试上升到一个新的艺术台阶。
以前那种依靠人耳主观听音来调整超低音扬声器位置，或是播放最熟悉的管风琴音乐来猜测低音频率的那种时代已经一去不复返了。你要知道，在调试过程当中，我虽然也会采用人耳聆听的方式，但那也仅仅作为现场效果的检查而已。主观听音可以告诉我们调试是否准确，但是远远没有使用设备来得高效，因为设备可以进行精密测量并分析问题，最终帮助你解决问题，这一切依靠主观听音是无法做到的。
（如何找到合适的炮位更加考验调试工程师的功力）
The primary calibration issue with subwoofers is how low frequency sounds resonate inside your room. These resonances create the characteristic boom and bloom sounds which seem to emanate from everywhere except the soundstage. Such blooming or ringing pulls our minds eye from the focused imaging created by the Left, Center, and Right speakers (LCRs). This often exposes the sub as a localizable source. You see the first sign of a poorly calibrated sub is the listener’s ability to localize the subwoofer when it plays. A well behaved sub will seem as if it’s quietly doing nothing meanwhile all focused images appear to have loads of bass flowing from them.
超低音调试的首要目标就在于了解低音频率在你的房间里面是如何共振的。这些共振会在房间里面产生很特别的共鸣效应，你会感觉臃肿不堪的低音来自四面八方，而不是从正前方的声场处传过来。这种拖泥带水、臃肿不堪的低频效果会将你的注意力从前方LCR所形成的精准定位声场分散开去。这样的效果往往使得超低音扬声器变成一个定位感明显的声源。
超低音调试效果的好坏就取决于听者能否一下就听出来超低音位于哪个位置。而一只表现优异的超低音是完全让人感觉不到，但同时所有的声学结像都完美呈现，你只会感觉舒适悦耳的低音静静地流淌在整个房间里。
（HAA一级理论课关于房间共振）
What does a calibrator do to make a subwoofer sound good? 1) Set Subwoofer level preferably using a real time analyzer not just an SPL meter, 2) Set subwoofer phase by precisely tuning the sub time delay, 3) Smoothing the response of the subwoofer by a combination of mechanical repositioning and equalization. One needs to be prepared to move the sub because frankly there’snot better way to precisely combat resonances. In order to accomplish the same result with an equalizer, a calibrator must carefully tune each filter using a high resolution spectrum analyzer. Such a feat is not so easily accomplished by even the most sophisticated automatic equalizer system. It takes a trained and experienced calibrator to tackle the job. The results though, are well worth it. Perhaps even bringing even the most bass shy wife back into the theater.
那么我们的调试工程师具体该如何做才能让超低音发出如此美妙的低音呢？在此我有一些建议如下：
1）设置超低音电平最好是使用实时频谱分析仪而不仅仅用声压分贝仪就行了，要知道专业的工具可以更高效而准确；
2）超低音相位需要精确调整超低音的延迟时间；
3）超低音的频响平整度结合了机械定位和均衡器共同的作用而成。
假设你想要调试你的超低音，你确实需要充足的准备才可以。因为坦白地说，想要精确地减轻共振也没有其他捷径。假如你想要通过使用均衡器来实现同样的效果，那么你必须使用高分辨率的频谱分析仪来非常仔细的调试每滤波器设置参数，而且即使是最先进的自动均衡系统也很难达到如此效果。这需要一位训练有素且经验丰富的调试工程师通过手动调试来完成这项工作。
尽管调试过程稍显复杂，但是为了能听到最好的低音效果还是非常值得一试的。也许经过这样的调试以后，先前那位对低音产生恐惧感的美女太太或许愿意再次踏入您的家庭影院，与您共享美妙的音乐或是相互依偎一同观看最新的大片呢。
你必须知道的低音炮七问！
http://www.mottu.cn/?p=15086
（Sandy编译）
如果你觉得这篇文章对你有用，请分享出去，让更多的人知道高水平音频调试的重要价值 
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发表于 22-5-2014 07:58 AM
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