I finally received my DJI Mic after pre-ordering it more than a month ago, and at first, I was disappointed. When I did the initial test with the DJI Receiver connected to my Canon R5, the audio I recorded was much noisier than what I was used to from my old setup, for which I used a Zoom H1 with a Rode Lavalier GO. But there's a solution to this problem, and in this article, I share it with you.
First thing's first: this is not a full review of the microphone. I didn't have it long enough. When I buy new equipment, I make sure with a set of initial tests that it works properly and does what I want it to do. If it does not, I send it back within the return period. And to be honest, that's what I thought I might have to do with the DJI Mic after listening to the first recording. But as you'll soon learn, the noise resulted from the wrong settings in both microphone and camera. The DJI Mic can provide very good audio quality if used correctly.
Recording a Backup Track
The first thing I did to identify the problem was record a backup track directly to one of the transmitters. It's a handy feature that I will use a lot. The transmitter has a dedicated record button that starts the backup recording independently of the camera recording. With it, I can either record a backup track in addition to the audio that goes into the camera via the receiver, or I can use it as my stand-alone audio recording solution when filming with the GoPro.
So how did the backup recording sound? I'm glad to say that there was no audible noise present, which tells me that the noise in my previous recording was introduced somewhere in the transmission chain between the transmitter, the receiver, and the camera. You can listen to this much improved audio signal in the second section of the feature video.
Once I opened the WAV file of the backup track in DaVinci Resolve, I noticed a low audio level. I had to intensify it by more than 16db to align it with the audio I had recorded on camera before. Because this backup audio signal is very clean, intensifying it in post-production didn't introduce any noise.
It tells me that during my first test, the audio signal must have been intensified by a similar amount inside the camera because I had not applied any other gains in the DJI Mic. Since the audio signal going into the camera is already a decoded analog signal, any noise that's introduced now is intensified as the camera boosts the audio signal.
Applying Gain in Transmitter and Receiver
In the DJI Mic, you can set the gain in both receiver and transmitter independently to values between -12db and +12db. You should adjust the transmitter gain to a value, which results in a strong audio signal that does not clip. On the receiver, there's a level indicator, which helps to fine-tune this setting. You can also boost the audio signal in the receiver itself by applying an additional gain before it goes into the camera. While having the microphone connected to the Canon R5 and my Dell XPS, I found that I must boost the signal significantly to avoid noise.
The later in the audio chain the audio signal is intensified, the more noise you get. The worst thing you can do is set the audio levels in the camera to auto and the gains in the DJI Mic to a low value. The camera will then increase the audio level with all the noise that's introduced along the way. That's what happened in my first test when I had everything set to default. You can hear it in the first section of the feature video.
I'm still experimenting with different settings, but what works for me now in an office setup without any ambient noise are the following settings:
I set the gain in the transmitter to +6db
In the receiver, I apply +3db
I control the audio level in the camera manually and set it to a value of 50% or less
It results in an audio signal of similar intensity as in my first test but with much less noise.
Now, I encourage you to do your tests and fine-tune those settings to what works for you. I will also try to further improve the audio by experimenting with the gains. But I felt that it's important to share this now so the information is out there and you're not as confused as I was in the beginning. If you film a lot, this is surely nothing new for you. But for me, there's still a lot to learn when it comes to audio and video recording.
How to Synchronize Audio and Video
Since the backup recording sounds so good, you might want to always record it in addition to the audio you record on camera. If you somehow mess up the gain settings, and the audio signal recorded with the video gets too noisy or clips, you can exchange it against the backup track.
In modern video editing software, synchronizing audio and video is easy. As an example, I want to share how to do it in the free software DaVinci Resolve. Before dragging the video and audio clips into the timeline, select both in DaVinci's file explorer, right-click on one of the files, and select "Auto Sync Audio - Based on Waveform". It will work perfectly for the backup track because the audio source is identical to the audio in the video file. The only differences are intensity and noise level.
To avoid confusion as you record many video and audio clips, ensure that the time and date settings in both the camera and the DJI Mic are the same. In DaVinci Resolve, you can then order the files based on their creation time, which will make it much easier to find corresponding tracks.
Finally, let's hear your experiences. Do you also have a DJI Mic or a similar microphone? What settings work best for you?