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Connecting a DSLR or Camcorder to an External Mic

If you want to produce high-quality audio to go along with your video, you need to know how to connect a microphone or soundboard to your camcorder. This tutorial will show you, first for a traditional camcorder with XLR connectors and then for a DSLR with a 1/8" jack.

Connecting a Mic to a DSLR or Camera With a 3.5mm Connector

Although there are adapters that you can buy to convert XLR input to 3.5mm output, they don’t supply phantom power to the microphone. In addition, if you’re using a wireless audio system with a battery-powered receiver and mics, the receiver typically includes both 3.5mm and XLR output to work with a range of cameras. You don’t always need a unit like the Comica CVM-AX3 shown in Figure 10 (on the previous page) to work with professional audio gear. However, if you need phantom power, you’ll find such a device indispensable.

As you can see in Figure 10 (below), the CVM-AX3 supports both XLR (Input 1) and 3.5mm connectors (Input 2) and can supply both phantom power and 3V plug-in power. Note the Feelworld 4K monitor on the right in Figure 10, which is made absolutely essential by the lack of a headphone jack on the Sony a6300.


Figure 10. The Comica CVM-AX3 supplies phantom and plug-in power with a 3.5mm output for my Sony a6300.

To get everything set up and connected, turn on the adapter (Figure 11, below), plug in the microphone (Figure 10), enable phantom power (Figure 10), and connect the adapter to the camcorder via the supplied cable on the left in Figure 11.

Figure 11. Setting levels in the Sony a6300

Next, adjust the outbound levels of the adapter and the incoming levels on the camcorder to produce adequate audio. During normal conversation, your audio should peak at the -3 dB level shown in Figure 11.

Technically, what we’re doing when setting levels is boosting the microphone input so that it’s clearly audible, which is an operation that a high-quality pre-amp can accomplish better than a poor-quality pre-amp. I’ve watched tutorials advising that since the pre-amp on an inexpensive DSLR might produce lower quality than that on an audio device like the Comica, you should set levels as low as possible in the camcorder and boost the signal in the adapter. That’s why the Audio Rec Level in the a6300 is set to 4 in Figure 11, and the Comica’s volume controls are set close to the max.

I experimented both ways—low in the camcorder and high in the adapter (and vice versa)—and didn’t notice any difference. Still, particularly if you’re pulling audio from a high-quality soundboard, it’s best to keep levels low in the camcorder and increase the volume in the external device.

Connecting to a Soundboard

If you’re shooting an event with audio routed through a soundboard, you’ll want to input that audio into your camcorder for live streaming or recording if at all possible. With the workflow you’ve learned in this tutorial, connecting to a soundboard should be straightforward; just make sure your inputs are set to Line power, and go through the steps. However, there are typically three things to consider when connecting to a board:

  1. Location, location, location. Make sure the soundboard is proximate to where you want to set up your camera. If not, run a cable from the soundboard to your camera. This is best done early so you can tape the cable. You should use a balanced cable, such as an XLR or 1/4" TRS (tip, ring, and sleeve) cable. I don’t have time to go into balanced versus unbalanced here, but if you have a long cable run from the soundboard to your camcorder, you’d better study up on this.
  2. Make sure there’s a spare output for you. Soundboards have multiple outputs, but in a live event, many are used to feed speakers, recorders, and other devices. So ensure that there’s a spare output—preferably, two outputs for a stereo signal.
  3. You’ll probably need to buy a cable or adapter(s). Once you know what output is available, you have to figure out how to connect it to your camcorder. As an example, 1/4" plugs are popular with soundboards, so you’ll likely need a 1/4"-to-XLR adapter and perhaps a 1/4" stereo adapter to separate XLR signals.

All of this means that you should contact the soundboard operator as soon as possible before an event to iron out these issues. You should also try to connect to the soundboard before the event, while you still have time to swap out cables, plugs, or adapters, if necessary.