A very useful accessory for people using DSLRs and Mirror-Free cameras to produce video. This is a low cost favorite.

BeachTek DXA-2T. A tough little box.

The three different cameras types I have all allow for shooting decent video. The D810 has the best look to the images while the OMD EM5.2 is a great handheld, ENG camera. The image stabilization is nothing short of amazing. In an ambiguous third place is my inexpensive, Nikon D610 which has decent looking video (not as nice as the D810) but no real image stabilization. The one thing all three of these camera have is the ability to manually adjust sound levels. All three also have microphone inputs on the camera as well as headphone jacks for monitoring audio. 

The other thing all three camera types have is not so good. All of them use menu driven (not physical knob controlled) audio level controls. This makes adjusting sound levels during recording a more complicated undertaking. For the lazy filmmaker it may be just the thing to push us into using auto level controls instead of working a little harder to get the audio just right. 

I cheat. I use the little box you see under the camera (above) to do three different things for me when I make video that has to have good sound.

1. I run any external microphones through this box because it has a hard knob (with detents) for each channel (left and right) so this allows me to set a middle level on the camera, say minus 12 dB, and then have the ability to adjust the levels downward via the knobs on the box. The DXA-2T is passive and won't amplify signals but it's a clean way to manually prevent overload into the camera's audio circuits without resorting to ALC and heavy handed limiters. And it beats trying to open up menus on the screen while shooting... 

2. I can run unbalanced stereo mics in through a 3.5mm plug or I can plug in real, balanced mics to the XLR plugs on the box. The advantage here is that the box has internal transformers that match the input characteristics (resistance, etc.) of professional microphones to what the camera's little, pixie pre-amp circuits are expecting. The best match is to microphones like the Rode NTG-2 which has the option of running its own internal pre-amp via a double A battery instead of requiring phantom power (which this box does NOT provide).  The transformers seems to have the effect of reducing noise and matching output and input more efficiently which translates into a stronger, richer signal delivered to the camera.  Being able to adjust the knobs on the box during recording in order to reduce overall volume is a big plus. The only time you'll need to go into the menus are when you need to boost the signal.

3. Sometimes I want to use a Zoom H4n digital audio recorder to record the audio but I also want to run that audio into the camera at the same time. The only way to do that on an H4n is via the "line out" port into the camera's microphone input. But the line out is about 35 dB stronger than what the camera expects (or is designed for) from a microphone and the sound in camera is quickly and sometimes massively overloaded. Unlike the newer digital audio recorders there's no switch on the H4n to drop the signal to match the camera's inputs. But there is such a switch for each channel on the DXA-2T. That means I have the option to run back-up sound right into the camera where I can also monitor it with headphones. 

I could also use the "line in" setting on the box to accept balanced inputs from a mixer like the big one they use at Zach Theatre. Then I can pull clean sound into the camera sound track if I am recording a musical performance without worrying about overloaded signal circuits.

The DXA-2T is a totally passive device which means no batteries and less chance of device generated noise. It's a sturdy little beast and it fits just about anywhere. I carry it in my microphone case along with duplicate cables for everything. It's wonderful not to have to go menu diving to make quick, small adjustments.  I've forgotten what I paid for it which basically means that it's so practical and useful that it's paid for itself many times over. The only issues I have with this box are the times when I forget to pack it and end up leaving it at the studio.