How to Master the Art of Digital Audio Mixing for Hybrid Events
Mixing audio for a venue is a well-documented practice. 在最基本的层面上, 它需要麦克风, 预先录制的音频源, 一个音板, 喇叭, 和, 最重要的是, 熟练的操作员. 现场音频的两个最常见的挑战是避免和消除反馈和地面环路嗡嗡声.
为视频录制或实时流混合音频涉及许多相同的技术和设备, 但每个都有不同的生产标准，你不必担心使用扬声器的现场扩声. 直播音频的两个最常见的挑战是获得干净的信号和在更小的范围内混合音频，如果你只是为场地混音.
Neither of these two is very complicated to explain 和 implement, 虽然, 在实践中, mixing live audio can be very challenging because of room dynamics, 电气接地问题, 和, 最重要的是, 麦克风技术.
作为直播专家, 我的观点将与现场音频技术人员处理场地音频的方式有所不同. 主要原因是我同时考虑了现场观众和直播观众.
在本文中, 我解释了我同时为这两种环境混合音频的方法. 在我的事业中, 我把既有现场观众又有现场观众的活动称为混合活动, 我们制作的大部分作品都是针对双重观众的混合活动. 随着时间的推移, we’ve found that we prefer to h和le the audio for both audiences, rather than trust part or all of this to an external A/V company. 最大的原因是，室内观众的需求与在线观看观众的需求不同, 如果音频技术人员只为房间混合音频，而不参与或监控直播流的音频, the audio levels may not be within a desirable range.
So, with that lengthy preamble out of the way, let’s start with the basics of mixing audio for a live venue.
Step 1: Connecting audio sources
将麦克风和预先录制的音源连接到音板上，最好使用XLR或¼“TRS电缆等平衡连接. 使用平衡连接有助于减少来自电磁干扰的外部噪声, which is especially an issue with longer cable runs.
Step 2: Setting the pre-amp levels
When you connect a cable to your soundboard, regardless of whether it’s a digital board or an analog one, you need to set the preamplifier levels for each input. The pre-amp levels can also be labeled as gain or trim. 有些板有电平指示灯，当你在正确的范围是绿色的，如果你的信号太热红色. 所有的音频信号，你永远不会想剪辑你的音频在任何地方在你的信号流. This is similar to protecting your highlight when shooting video.
Step 3: Confirming clean audio
You can confirm clean audio with headphones or speakers. 这是当你听明显的问题，如地面环路嗡嗡声或嘈杂或失真的音频信号. 当你将A/ c供电的音频设备连接在一起时，会发生地环路嗡嗡声. 正常情况下, equipment grounds to the A/C plug it’s directly connected to, 但有时, due to differences in grounding potential, the device chooses the path of least resistance through your audio cables, not to the ground on the plug. 这会导致地环路嗡嗡声.
This electrical interference hum needs to be eliminated. The solution is to add a direct box (aka a DI, 下面的图1) into the workflow to lift the ground 和 force the devices to ground, 按预期, 连接到各自的插头上. 当您从远程笔记本电脑连接音频时，应该自动使用DI来提升地面并将不平衡信号转换为平衡的XLR连接.
图1. A 百灵达迪
Step 4: Setting PA speaker 和 soundboard volume levels
我把扩音器的音量调到四分之一，然后把每个输入和主输出的音量调高. If your levels are set properly, 您应该在一个范围内操作，其中输入和输出的电平刚好低于电平转换器上的0的奇偶校验电平. If your fader levels are too high, then you don’t have any ability to increase the levels as needed, 和 if they have to be set too low, 这意味着你的扬声器设置太高，直播流的信号将不在一个理想的范围内.
要在扬声器的音量之间找到适当的平衡，可能需要一些来回的时间, 输入量, 主要输出量, but this is all a part of mixing professional audio. 在这一步中, you are generally getting the audio into a proper range so that you can move on to the next step; you can then return to this step to get your final show levels set.
Step 5: Equalizing your audio
一般, this step is part of Step 4 because, 大多数时候, you will find that when setting your audio levels, you get feedback before the audio gets to show levels. 当你有多个麦克风，尤其是全向麦克风，比如lavaliere麦克风时，这尤其重要. 反馈是当某些音频在房间里反弹，并以比其他频率更高的水平返回麦克风时发生的情况. This creates a feedback loop that instantly turns into a mounting squeal. It has to be terminated immediately by manually turning down the levels.
每个房间的不同之处在于哪个频率会比其他频率反弹得更厉害. Some audio technicians claim they can hear 和 identify the feedback frequencies, 但我更喜欢依靠简单的频谱分析仪来准确识别哪些频率在响. If I am using a 数字音板 like the 百灵达X18 (下面的图2), 我可以参考100波段实时分析仪(RTA)来监控和识别问题频率, then use the equalizer to turn down the levels only on those specific frequencies. This is more precise than turning down an entire range of frequencies, like you do on most analog boards, 和 is one of the reasons I prefer 数字音板s.
图2. 贝林格X18 数字音板
音频均衡(EQ)可以在单个输入或主输出作为一个整体上完成. 正常情况下, 你可以在前面提到的全向麦克风上增加一点EQ，这些麦克风更容易产生反馈，而在心形手持麦克风上则更少. 当你在做情商的时候，你也要小心不要做得太过火, or the resulting signal may sound too much like it was recorded in a fishbowl.
在模拟音板上，你可以得到的精确程度将受到限制. Most boards limit you to only three controls: high, medium, 和 low. 我觉得这个限制太大了, but this is what most small-venue operators use, 和 it reinforces my preference to manage my own audio.
My favorite line of 模拟混合机s is the 麦基ProFX V2 line (下面的图3)，因为我使用的8声道和12声道型号有一个7波段立体声图形均衡器, 这让我比传统的三通道均衡器更精确. 不幸的是，新的V3系列取消了图形均衡器，而采用了压缩器.
图3. 麦基ProFX V2 模拟混合机
Before I moved to a digital mixer with a 100- b和 graphic equalizer, I used the Behringer FBQ1502HD 15-b和 EQ. 尽管它确实具有反馈检测功能，可以点亮具有最强信号的频率, I found that there were too many false positives, 和 I got better results using an external spectrum analyzer. This might sound like a fancy piece of tech, similar to an expensive light meter for exposure, but I’m talking here about a free, downloadable cellphone app called Advanced 频谱分析仪 PRO for Android (下面的图4)，也没有广告.
图4. 先进的 频谱分析仪 PRO安卓应用
调节房间的声音就像慢慢增加音板上的音量一样简单，直到你开始听到反馈. 然后, using the RTA or a 频谱分析仪, you determine which frequency is spiking 和 causing feedback. Next on your graphic equalizer, lower that specific frequency. You can then increase the volume again to target the next-worst frequency.
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