Friday, February 27, 2015

Zoom H1 Automatic Safety Track Adapter

I've always liked the idea of the recording a safety track when recording dialogue. This is the practice of sending your mono mic to one stereo channel, and a slightly lower version of the same mic to another. If your actors yell or otherwise clip the main channel, the safety channel is perfectly useable and saves the audio.

While all (that I know of) XLR recorders have this feature built-in, 1/8" recorders such as the Zoom H1 don't even allow you to individually control both stereo channels, only both at the same time. Even if you can get your mono mic into both channels (using a mono-to-stereo adapter), you can't bring one of them lower than the other. In the past I've worked around this, but it requires a mixer of some kind. What I wanted was an adapter that would automatically drop that second channel about -12db for safety.

I'm an electronics amateur at best and was unsure how to do this, so I poked around on YouTube and came across this video about a DIY attenuator that did just what I was looking for. It sent me in the direction of creating my own cable, even if my wiring ended up a bit different.

I can see a lot of applications for this, a big one being body mics. Putting a mic on a groom is a common practice, but there is no way to monitor his sound once you set him free to get married. The Safety Track Adapter could help set your mind at ease knowing that your chances of recoverable sound are good, even when he gets loud.

The best things about this project is that it's very affordable, looks professional, and only requires beginning soldering skills. This adapter can easily built in an hour if you know your way around a soldering iron. Please let me know how yours turns out and if it helps.

1' male to male stereo audio cable
1/8" (3.5mm) female adapter plug
2 resistors (depends on mic impedance and voltage)
electrical tape

soldering iron
rosin core solder
wire cutters/strippers
"helping hands" device (optional, but you'll want it)

1 comment:

Dan said...

Great! This is exactly what I was hoping for. Thanks for explaining how to calculate the values of the resistors.


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