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Tutorial: Making the Right Audio Connections for Live and Corporate Video

In this article we'll walk through the process of connecting a camcorder to an external microphone or soundboard for optimum, clean, balanced audio capture--critical skills for any videographer or online video producer doing corporate video or live events.

Step 5.  Select line or microphone input

Microphone input is weaker than the input from an soundboard or other similar device. To handle both, cameras have microphone/line switches that let you choose the input. In this case, since I’m connecting to a microphone, I’ll choose Mic (Figure 4, below). Note that if you’re connecting to a microphone and don’t hear anything in the headphones, it may be because you’ve got this switch configured to Line. If you’re connecting to a powered device like a soundboard, choose Line input. 

Canon XH A1
Figure 4. Choosing between Line and Mic inputs.

Step 6. Enable attenuation, if needed

Sometimes in either Line or Mic mode, the signal is too powerful for the camcorder to handle without distortion or too much ambient sound. This is the case with the Azden shotgun microphone, so I’ve enabled attenuation (Figure 5, below), which reduces the incoming audio levels by 20 dB. How do you know when the signal is too hot? After you enable manual gain control and set the volume controls at mid-level, if the volume is bumping against the top of the volume meter, you should try attenuation.

Canon XH A1
Figure 5. Attenuating the signal from the Line and Mic inputs.

Step 7. Choose your gain control strategy: manual or auto

The switch at the bottom of Figure 6 (below) controls whether I use automatic gain control, where the camera controls the volume, or manual, where I use the two dials above the switch to control volume. Typically, if I’m driving only one camera in a fairly static setting, like a seminar or speech, I’ll use manual gain control. On the other hand, in dynamic setting like a concert where I have continually try to follow the action and adjust exposure, I’ll usually go auto.

Canon XH A1
Figure 6. Choosing between auto and manual volume  controls.

Note that the old complaint about auto gain control was that the camera would boost gain during silent periods, creating audible noise when it’s supposed to be quiet. However, this isn’t a behavior I’ve noticed with any of my prosumer camcorders. If anything, the camcorders are much faster to adjust to changing levels than I am, and are always paying close attention.

When you’re pulling audio from a soundboard, the board jockey is making almost continual adjustments to volume which are nearly impossible to respond to, particularly if you’re trying to follow the action with your camcorder. Auto will make sure you don’t clip at the high end, or record too faintly at the low end.