Never underestimate the value of audio. Often times the audio is overlooked on a video shoot, yet depending on your project the audio may convey half of the content or more. The new wave of DSLR cameras has revolutionized shooting video in a lot of ways. Indie filmmakers and amateurs alike are now able to achieve a cinematic look on a relatively affordable budget. These cameras however, lack high-end audio to match. The cameras themselves do not come equipped with adequate microphones, and the cameras are limited in their audio inputs. This leaves you with a couple options; use a small mixer, a mic designed for a DSLR, or a separate audio recording device.
Mic, Mixer, or Recorder
Having a mic specifically designed for a DSLR can be the most affordable; nevertheless it is the most limiting and not always the best quality. Though a separate audio recorder might achieve better audio, it would also require double the button pushing during recording and extra work syncing during editing.
Often times, carrying a mixer around with you on a video shoot is not practical or affordable. Azden’s FMX-DSLR mini mixer solves that issue. This handy little mixer mounts directly to the bottom of the camera and to the tripod head at the same time, acting as an in-between device to your camera-tripod setup. This is a natural location for the mixer. While there are few mounting options, at least the form of your camera is still capable of being handheld operated. There is a nice professional build to the device and it seems solid, however the specific design of the FMX-DSLR is slightly quirky since it is slightly longer on the front side, causing it to protrude out from beneath the lens of most cameras.
The mixer itself has two XLR inputs, with volume control for each. XLR inputs are a big plus and leave your options open for lapel mics or condenser mics of your choice. Ultimately, the most professional mics will make used of the XLR inputs, and you are resisting the addition of adapters to your video setup. The mixer has an 1/8-inch headphone jack and audio monitoring is easy enough on the FMX-DSLR. One drawback to be aware of, is that most DSLR cameras do not have an audio out for you to hear what the camera is recording. Playback of the video clip becomes necessary to be sure the audio recorded properly, which would become a big issue at live events such as weddings where you only get one take.
When monitoring your audio, there are no audio level meters on the FMX-DSLR mixer. That is tough. Since you can only hear what the mixer is hearing, not what the camera is recording and without levels it becomes fairly difficult to adjust the audio properly. You’ll be relying on your attention to audio to get it just right, In addition, Nikon and Canon cameras have an AGC (Auto Gain Control) causing the camera to automatically readjust your incoming audio. By default, there is no way to disable the AGC on most Canon or Nikon DSLR cameras; meaning unless you install a third party firmware, you are limited to auto controls on all your audio despite the fact that the mixer has volume controls.
Not only do most DSLRs default to AGC, but the Azden FMX-DSLR mixer also has an AGC switch. Azden claims the AGC creates “noiseless operation.” In our test, the AGC produced a loud high pitch noise during recording, making the recorded clips unusable. When the AGC was switched off the mixer preformed well and delivered good audio with fairly little noise. Switching off the AGC is a trick! The switch is hidden on the bottom, opposite of the volume dials. Unless you take the mixer off the tripod and search the mixer, the switch is easy to overlook. While the recessed switch allows for flush mounting, the AGC can only be switched on or off with the camera detached.
In the Field
In our field test, the Azden FMX-DSLR mixer preformed rather well. The battery life was substantial. Azden claims a 15-hour run time on four AA batteries. In our test the mixer lasted more than 15 hours of interviews and four hours of live event performances, a welcome surpassing expectation. A nice touch is that the AA batteries are very easy to switch out; so often do small electronics tuck away batteries seemingly forever – the FMX-DSLR slides out a carriage for all four batteries with open borders to easily handle both sides of the battery. For a video interview with a decent pro lapel mic, we were able to get good clear audio with little noise. We discovered that in order to get a condenser mic to work you must switch the appropriate channel (L or R) DC48V to “on” and these two crucial switches are found near the AGC switch.
All in all, the Azden FMX-DSLR mixer performs well. The mixer is small and compact and fits right under the camera. The mixer comes with a coiled 1/8-inch cable, and there is no extra mounting gear needed to make this mixer work and you can utilize it handheld or on a tripod. The battery life surpassed the manufacturer’s claim. The overall audio quality is good. It’s priced affordably and looks professional.
Main and Unbalanced Output: 20-20,000Hz (+0/-1dB)
Monitor Output: 50-20,000Hz (-1dB)
Left & Right Channel: -110dB
T.H.D.: less than 0.01% @ 1 KHk
Line/Aux Low setting: Max Input Level +22dBu Max Gain -22dB
Line/Aux Hi setting: Max Input Level +6dBu Max Gain -6dB
MIC1/MIC2 Low setting: Max Input Level 0dBu Max Gain 0dB
MIC1/MIC2 Hi setting: Max Input Level -16dBu Max Gain +16dB
1/8″ (3.5mm) Stereo: -3.5dBu (32 ohm load)
Maximum Output Level (unbalanced): (3.5mm) +0dBu (2K ohms)
Battery Type/Life: AA (4) Alkaline 15+ hours with phantom power off
Current Drain: 40mA nominal (Phantom Power Off) 80mA maximum (Phantom Power On)
Phantom Power Voltage: 48VDC (+/- 2VDC)
Size (HxWxD): (1.75″ x 4.2″ x 4.2″) (44x105x105mm)
Weight w/o Batteries: 16.6oz. (470 grams)
- XLR inputs
- Volume control knobs
- Long battery life
- Slightly larger than a DSLR camera base
- Limited by camera’s audio quality and AGC
This is the perfect camera for the shooters on the go that love to show off what they did in the moment.
Luke Scherba is a video producer and production studio owner.