How to Master Audio Mixing for Live Production and Streaming
另一方面, if you feed a mic level source into the line-level jack, you’ll find yourself cranking everything all the way up and wondering, “Why the heck am I not getting any sound out of this?“你把东西调得越大，信号路径上的嘶嘶声就越多.
坏的均衡
Next we’ll look at equalization (EQ) adjustments (图3). Let’s say you want someone to have a strong, booming presence in the room. You’ll need to increase the gain of the low frequencies, 注意，您之前设置的输入级别现在要高得多. The EQ does affect the input level, 尽管从技术上讲它不应该，因为它在音频路径的更下方. 但它确实如此，你必须回到输入电平并在设置你的EQ后重新调整它.
高频也是如此，尽管你可能不会注意到它们. 但如果你的高频均衡器太高，而你没有调整你的输入修剪来补偿，它们就会变得刺耳.
锅太高，锅错了
在混频器的底部，你会发现泛盘控制和电位器(图4), both of which are critical to getting a consistently professional mix. On smaller mixers, the potentiometers, or pots, are boring little knobs. On the mixer shown in 图4, they’re much more appealing sliders. 每当有人走到搅拌机前，他们首先要碰的总是滑块.
On audio mixers, you can see that there’s headroom above zero. That’s gain, or amplification, of the signal. 当你需要使信号比它进来时更响时，滑块就会去那里. 如果你发现你的滑块/锅总是高于零，是时候重新检查你的输入修剪了. 可能太低了.
当人们不熟悉音频混音器上的数百个旋钮时-特别是更大的混音器, with their multiple sweepable EQs, 并且在每个通道上都有多个aux发送和返回-他们看到混频器底部的“pan”旋钮，并决定它只是另一个可以忽略的旋钮. 如果有人调整了搅拌器上的平底锅，并且平底锅旋钮都以某种方式进行了调整, 你会想知道, “Why am I getting sound out of only part of the system?”
如果你只用一个搅拌器制作多个饲料，那么有效地使用锅控制就显得尤为重要. If you’re using one mixer for both streaming and house sound, you can take that main mix and split it. 左边的通道是你的流，右边的通道是你的房子. 这使得它很容易推一个滑块，并提高水平平均在你的流和在房间里. But you have to make sure the pan is set correctly, or you might find that one of your microphones is audible only in the room, 而不是在网络直播流上. Mastering the pan control is critical to avoiding those situations.
图5 shows a mixer that has separate left and right controls for the main mix. But if you have a smaller mixer, it will most likely have only one knob. You won’t be able to adjust one channel or the other independently. pan控制将是你调整每个通道对混频器的主立体声输出的贡献的地方. But even with separate Main Out sliders, 你仍然需要注意你正在处理的每个信号的锅设置.
图5. Some mixers have separate left and right main mix sliders; others have just one knob.
混频器后过调
If the final mix that you export is wrong, 实际上，您可以在放大器或流媒体设备/笔记本电脑输入上剪辑音频. One of the key reasons is that not all line levels are created equal. Professional line level is +4dB, and consumer line level is -10dB. If you’re using a professional mixer, on the back you’ll find a switch that allows you to adjust the output level; if you don’t have such a switch, you’ll need to adjust your mix to compensate.
如果你要把你的混音器输入到消费类设备中比如处理你的网络流的电脑, make sure you’re not feeding it professional line-level out. 即使你把电脑设置成线输入，声音还是太大了. And if you happen to plug the mixer into the computer’s microphone input, you’ll have to take the mixer’s output way down.
至于房子的组合, 为房间供电的功率放大器被设置为专业线路电平，因此它们期望得到更热的信号. 你的混频器的网络流输出在房间里听起来不会很响，因为放大器期望得到一个更热的信号. 你必须确保你输出的每个feed都是正确的水平.
反馈
How many times have you heard feedback during a presentation? We all know what feedback is: The room audio gets into the mic, 哪个能进房间, 哪个会进入麦克风. 图6 shows what feedback looks like on a scope. This has a spike around the 1k tone, 但这里有一个主要的反馈峰，然后你可以看到有两个泛音:一个在2k以上，一个在5k以上.
If you have a 30-band EQ, you can use it to correct room audio. Operators will often notch the feedback without notching the overtone. Those frequencies are hanging around, ready to give you some feedback. 值得庆幸的是，如今反馈很容易管理，我们可以用硬件来消除它. 在本文的几个图中出现的百灵达 Eurorack混合器具有反馈灭虫器(图7). 你要做的就是按下按钮, 数字电路一听到反馈就会设置一个缺口.
图7. The 百灵达 Eurorack mixer has a built-in feedback detector.
一般来说, 百灵达 box offers enough capabilities to handle most easy room problems. Then, of course, there’s an EQ for the room as well. 如果你发现房间的组合有点沉重，你也可以纠正它.
If you don’t have a mixer that handles feedback effectively, 你可以购买舷外设备, 例如图中的鲨鱼 图8下一页. A lot of companies make similar boxes now. The Shark goes in between the mixer and the amp. It takes the output of your mixer, 听升调, and adds a digital notch that kills it. 它也可以用来延迟音频，所以它匹配你的视频，如果有任何视频延迟, 比如通过视频混频器. 这可以加强你的流上的音频同步，是一个方便的工具，在你的工具包.
是很重要的, 虽然, 需要注意的是，您需要正确设置这些反馈灭虫器以有效地使用它们. You’ll find producers who go into a room before a big show, 把麦克风拿出来, 把它们放在桌子上, 然后慢慢提高浓度. 随着“沉默”越来越响亮, they’ll hear those frequencies that are first to produce feedback, 然后消除它们. 然后他们会把音量再抬高一点，听到第二个音符，再给它一个刻度. 从技术上讲，你可以试着继续下去，但如果你这样做了，你会得到越来越多的反馈. 这些设备所做的就是让你在房间里的声音比没有它们时大几个分贝. 在许多房间里, 会有帮助的, 但是在一个困难的房间里, a room with marble on the walls—that’s going to be tough, 因为它很反光. You might have to keep your overall audio level much lower.
我在一个主要大厅有玻璃天花板和瓷砖地板的机构工作. 那声音很响. They had big speakers set up on top that shot outward over the whole hall. The sound bounced around a bit before it came down, and without a feedback exterminator, I couldn’t create a usable mix in the room. I could never get it loud enough on the floor, especially if there was a big crowd, because there was always a percentage of the crowd not paying attention, carrying on their own conversations, 聊天, 手机响了, 等等....... In those situations, feedback exterminators are essential.
掌握混音
在现场活动制作和流媒体中获得良好音频的关键是掌握从音频源到所有预期目的地的整个信号路径. There’s much more to it than plugging in a mic and pushing up a slider. 你需要在整个过程中确保适当的音频级别, and that includes several areas before and after the mixer.
您还需要知道如何避免在此过程中不可避免地出现的许多陷阱和潜在问题. By mastering the entire audio path, you can deliver professional-quality audio on almost any production.
This article appears in the May/June 2015 issue of 流媒体 as "How to Master Audio Mixing for Live Production and Streaming.”
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