Connecting a DSLR or Camcorder to an External Mic

All camcorders include an internal microphone, but you should never use it to capture audio for actual production. If you’re shooting a meeting or webinar, lavalier microphones will deliver better quality, whether they’re connected through the soundboard or directly to the camera. For a concert or similar event, you’ll almost always want to take audio from the soundboard.

So, 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.

Audio Basics

Let’s start with some basics.

XLR vs. 1/8" (3.5mm)

Most microphone connectors are either XLR connectors, shown on the left in Figure 1 (below), or 3.5mm connectors (also called 1/8" connectors), shown on the right. The majority of professional microphones use XLR connectors, which is why most professional camcorders have XLR plugs, while consumer camcorders and DSLRs have 3.5mm plugs. Although there are some high-quality mics with 3.5mm connectors, I think it’s best to work with XLR equipment whenever possible. If your camcorder has 3.5mm plugs, use an adapter or device like the Comica audio mixer (which I’ll discuss later in the article) to input the XLR audio and output a 3.5mm connector.

Figure 1. XLR (left) and 3.5mm (1/8”) connectors

Note that all XLR connectors are mono, while the two black lines in the 3.5mm connector transmit the left and right signals. If you need true stereo, you’ll need two XLR connectors, one for each channel. However, for most talking-head audio, stereo doesn’t really matter, so you can input a mono signal as long as you route it to both channels in your camera. You’ll learn how to do that here.

Powering Your Mics

There are two types of microphones: condenser and dynamic. Condenser microphones are generally more sensitive and can be encased in a much smaller package. For this reason, most lavalier (lapel) microphones use condenser mics. Note that condenser microphones need electric power to operate. So, if you’re connecting a lavalier microphone directly to your camcorder, chances are that you’ll have to power it.

Specifically, if you’re working with an unpowered XLR microphone, you’ll need to supply 48V phantom power, which most professional camcorders can provide. Figure 2 (below) shows the audio controls from my Panasonic camcorder; on the right are the selector switches that supply 48V phantom power to an unpowered microphone.

Figure 2. Audio controls for supplying phantom power

However, if you’re working with a battery-powered microphone like many on-camera mics, you don’t need to supply external power; that’s what the battery does. In these cases, you would turn phantom power off.

Note that condenser microphones with 3.5mm connectors require “plug-in” power, which is about 2.5V–5V. Many, but not all, 3.5mm plugs on camcorders and computers supply plug-in power; for example, the plug on my Sony a6300 does, while the plug on my old Canon Vixia does not.

Line vs. Mic Inputs

When connecting audio gear to a camcorder, note that there are two input levels, as shown in Figure 3 (below): Line and Mic. Powered devices like soundboards typically output Line-level outputs, which are approximately 1V in power. In contrast, microphones output just a few thousandths of a volt and require amplification circuits in your camcorder to boost the signal to a useful level.

Figure 3. Choosing between Line and Mic input

If you plug in a microphone and your input is set to Line, you likely won’t hear anything because the levels will be too low. If you plug in a soundboard with the input set to Mic, the signal will usually be loud and distorted. As you can see in Figure 3, professional camcorders let you switch inputs via a control on the camera body.

Most DLSR and consumer camcorders input Mic-level only, so you can’t directly connect a Line-level output to the 3.5mm plug. Instead, you’d have to use an adapter like the Kopul ACH4-25MON Line-to-Mic Attenuator Cable or a mixer like the Comica unit I’ll discuss later.

With this as our background, let’s jump to the first task: connecting a lavalier microphone directly to a camcorder.

Connecting a Lavalier Microphone to a Camcorder

Figure 4 (below) shows the Shure SM93 condenser lavalier microphone that I’m connecting to my Panasonic camcorder. The following are the discrete steps of connecting and setting up the microphone. Note that controls will vary from camcorder to camcorder, with some accomplished via the menu system rather than via the camera body. But you need to touch all of the bases to ensure connection and control.

Figure 4. Connecting the Shure SM93 condenser lavalier microphone to my Panasonic camcorder

Step 1—Connect the microphone to the camcorder. I’m using Input 2 for reasons that will become clear in a moment.

Step 2—Enable phantom power by clicking Input 2 to On (Figure 5, below).

Figure 5. Enabling phantom power

Step 3—Switch to the external microphone, and select Input 2 for both channels. On this camcorder, you switch off the internal microphone via the controls shown in Figure 6 (below). As previously mentioned, the XLR input is a mono signal, which is why I’m routing Input 2 to both the left and right tracks. This is the reason I plugged the microphone into Input 2; it’s the only input that I can route to both tracks.

Figure 6. Switching to the external microphone and routing Input 2 to both left and right audio tracks

Step 4—Select the Mic input for Input 2 (see Figure 3).

Step 5—Set the Mic levels. The Panasonic camcorder I’m using in this tutorial allows you to adjust Mic levels to either -50 dB or -60 dB, the latter of which is more sensitive and will boost the mic signal by an additional 10 dB. This may be essential if you can’t get adequate levels from the microphone (Figure 7, below).

Figure 7. Adjusting Mic gain

Other camcorders I’ve shot with have an attenuator switch that lets you cut 20 dB from the incoming signal when it’s too hot. Also common is the ability to add gain to the incoming microphone signal, which boosts the volume but can create noise. The bottom line is that your camcorder probably has multiple audio-related controls that you should get familiar with long before your first professional shoot or live event.

Step 6—Choose manual or automatic gain control (AGC). On most camcorders, you can either manually control the volume (Figure 8, below) or let the camcorder control it via AGC. Typically, in a talking-head scenario in which volumes don’t fluctuate all that much, you’re better off setting levels manually.

Figure 8. Going manual to set audio volume

Step 7—Adjust the volume to the target. This step is complicated by the fact that different camcorders use different level markers. For example, the Panasonic volume meter shown twice in Figure 9 sets a -12 dB target where most of your spoken audio should peak. If you hit the red, as you see on top of Figure 9 (below), the audio will “clip” and sound distorted.

Figure 9. The volume is too high on top as indicated by the red line. Instead, try to keep above -12 dB, but below the red.

You should also check to make sure the audio is relatively noise-free when no one is talking. If you see levels in the meter when everything is quiet, this means you either have some noise in the audio or you’re shooting in a noisy room. This would be a good time to remind you to record in a quiet room whenever possible. This means shutting off all computers and peripherals, phones, heating, and air conditioning, if possible, as well as putting a sign on the door to keep visitors away.

Never work with audio unless you have headphones to monitor it. Meters are fabulous, but you never know exactly what you’re capturing unless you hear it with your own ears.