B&H First Look: DN 101

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The proliferation of hybrid photo/video systems is gaining ground in almost all video markets. From weddings, to independent and broadcast production, the technology is ubiquitous. If you're shooting HD with any of today's video-enabled DSLRs, it's easy to see why. Large sensors, high ISO sensitivity, and lens selection are just a few of the draws to this new wave of content creation. However, these camera systems are just beginning to develop a series of standards, and are not without their challenges. From the Canon EOS-1D Mark IV to the Pentax K-7, the proper capture of usable audio is one such challenge.

 Many professional and prosumer DSLR cameras offer a 3.5mm audio input. This is good. The mini-jack allows shooters to connect a microphone or other audio equipment directly to the camera. What's notably missing, however, is the ability to monitor and control the levels of the sound being recorded. No current body from a major manufacturer offers an audio meter, headphone jack, or manual means of setting recording levels. To address this issue, the California-based company juicedLink offers a low-cost audio workaround with their CX series preamps and the new DN101 accessory.

       

The juicedLink CX231 (right) looks identical to the CX211 (left) but offers phantom power for XLR mics

By providing an affordable means of connecting balanced XLR inputs to camcorders with a standard 3.5mm stereo input jack, the juicedLink CX series has been quite popular with budget-conscious video shooters. The CX line-up is available in 2 and 4 XLR input versions with audio pan controls and optional phantom power and audio level metering. In theory, any member of the CX family could be attached to the 3.5mm input of a DSLR, but this wouldn't resolve AGC issues.

AGC, or Automatic Gain Control, is the primary problem in recording quality audio directly to a DSLR. Essentially, AGC changes audio recording sensitivity on the fly--lowering recording levels in loud situations and raising them in quiet ones. This is fine for grabbing quick clips for social networking content, but can be a real deal-breaker with a more professional production. This is where the new DN101 accessory comes in. By disabling Automatic Gain Control, the unit allows shooters to take advantage of the manual controls of a juicedLink preamp.

The juicedLink DN101 connected to the CX431 4-Channel Preamp

The DN101 bolts to the side of any CX unit. Using a standard ¼"-20 stud, the preamp is connected to the camera body via the tripod socket. The DN101 offers a levels meter, headphone jack, and a manual switch to disable AGC--a lot of features for an accessory that's about the size of a pack of matches. The preamp outputs to the DN101 input, and the DN101 outputs to the DSLR audio input jack. Both connections require male-to-male 3.5mm stereo audio cables.

To disable AGC, the DN101 ports a signal to the DSLR that reduces the sensitivity of the camera's audio recording amplifiers. This signal is not an audio tone, and therefore is not perceptible in the final sound recording. To overcome the low audio levels forced by the DN101 signal, audio gain is increased on the CX preamp. This creates a quality, controllable means of recording audio directly to a DSLR.

I tested the DN101 accessory with the CX231 preamp on both the Canon 7D and 5D Mark II. The results were impressive, and certainly improved my level of control over the recorded audio. I've used juicedLink preamps in the past and have always been satisfied by their dollar to value ratio. All juicedLink products feature durable, black metal casings that can stand up to the rigor of regular use. The base of the preamps has an etched "cheat sheet" for the main controls along with input/output requirements. The underside of all CX preamp cases feature a female threaded tripod hole and video guide pin adapter. This makes it easy to attach your set up to a tripod or shoulder mounted rig.

The switches and dials have a certain hobby store 'je ne sais quoi'. Although certainly capable of performing their job, these are the most delicate components of the juicedLink system. I recommend using a small piece of electrical tape to protect these controls during transport.

While there's plenty to like about the juicedLink DN101, there are also a few things that users should be aware of. First off, the headphone amp is not low-noise. The audio that you hear through your monitor headphones is not exactly the same audio that's being recorded by your camera. In AGC defeat mode, you can only hear the left channel. More on that in a moment. Using the non-AGC defeat mode, sound is monitored in mono. All of this is fine for down-and-dirty fieldwork, but discerning sound professionals would do better to record audio separately and sync in post.

Back to the AGC defeat mode. The DN101 beats Automatic Gain Control by injecting a strong signal into the right channel of the camera. The left channel is then used to record the clean "balanced" audio. This is why you can only hear the left channel through headphones in AGC defeat mode. To provide some sense of normalcy, the left channel is present in both the left and right ear cups. When setting up the preamp, make sure to set the Pan switches to the left position.

The AGC defeat method also has some implications on the editing of your project. Since the right channel is being blown out with a strong signal, you'll want to remove it from your timeline. Most non-linear editing software makes this easy to do. Just remember to do it. You want to edit with audio from the left channel only.

It's also important to note that attaching the DN101 to a CX preamp requires a bit of modification. There's nothing too drastic to be done, but you'll have to cut out a hole in the preamp battery door, remove a spring, attach some screws, and perform a few other little hobby shop mods. I understand that this isn't for everyone, but it's a requirement if you want to use the juicedLink system.

The DN101 and CX preamp combo seat well with any video-enabled DSLR with an audio input. However, the more you accessorize your rig, the more cumbersome the set up becomes. If you use a follow focus, matte box, or other cinema style accessories, managing the audio cables from the juicedLink system requires a bit of attention. I crossed wires with a follow focus whip a few times. The unintentional contact caused some interference with the sound recording.

As with customizing any accessory kit, it's important to prioritize based on need. The juicedLink system can be a bit cumbersome--especially considering all of the required cables. Being mindful and using the equipment properly yields some incredible results--none greater than having quality audio captured directly to your camera.

While several software hacks have popped up giving greater audio control to DSLRs, the juicedLink system is certainly worth considering. Hacked software doesn't address the needs of every DSLR model on the market, and damage caused by installing it on your camera could violate the terms of your manufacturer's warranty.

The DN101 and CX preamp combination stops short of providing a full solution to video DSLR audio issues. But the combo is a safe hardware workaround that provides shooters with the audio control they need, while keeping them in good standing with camera makers. It is my strong contention that this issue will eventually be resolved with software/next generation camera models. Some can afford to wait patiently. For those who need something now, the DN101 + CX preamp combo is one of the best workarounds on the market.

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Interesting. I didn't realize the AGC defeat mode consumed an entire track on the camera.

Very good blog post. So a good topic for a next blog entry is if you record the audio separtely using the Zoom H4 or similar device, how hard is it to synch the audio with video in post production without time code.

A co-worker of mine had a great idea. Use the Zoom H4 to record the audio separtely, but also use the line out of the Zoom H4 to connect to the mic input of the DSLR. In post production, use the audio that is recorded  with the video as a marker to help synch the audio from the zoom h4. Once the audio is synched delete the audio that was recorded with the camera and only use the zoom h4 audio in the final product.

I hear ya, Daniel. Ideally you want the audio recorded into the camera to be as close as possible to the audio recorded externally. However, plugging a line-level signal into a mic-level input is a severe mismatch. It's like plugging a drinking straw into a fire hydrant. Instead of recording a nice waveform of audio into the camera, you'll be recording a big distorted brick of sound that PluralEyes software won't be able to make heads or tails of.

I'm hearing rumors of manual gain control for the 5D Mark II in mid-March. Guess the writer was right.