Is there a setting in the device that allows you to record two stereo channels using a wireless mic via XLR and then adjust the levels of one of those channels as a safety channel?
Justin Davey is correct. There is no way to adjust the levels of the two XLR inputs on the H4n independently. However, with a few accessories you can pull this off without the need for a field mixer.
First you will need a Whirlwind IMP 1x2 microphone splitter. It splits one mic-level XLR input into two. I would not suggest using a Y-cable in the place of the Whirlwind IMP 1x2. The Whirlwind has impedance transformers that correct the signal flow. A Y-cable without impedance transformers will likely degrade the audio quality. You don't want to do that.
So, you would need to plug the XLR output of your wireless receiver into the input on the Whirlwind IMP 1x2. Then you would need a short XLR cable (like a Pearstone 1.5" XLR cable) to connect the "Direct" output on the IMP 1x2 into one of the XLR inputs on the Zoom H4n.
Next you will need an accessory called an "In-Line Pad" for the other output on the IMP 1x2. An In-Line Pad is a small barrel adapter that drops the level of the audio signal that passes through it.
So for the other output on the IMP 1x2, you would plug another short XLR cable into an In-Line Pad like the Audio Technica AT8202. You would then connect yet another short XLR cable from output of the AT8202 into the other XLR input on the Zoom H4n.
With all of these things in place, you will be able to record audio from your single wireless receiver into the H4n at two levels, creating the safety channel you desire. The nice thing about the AT8202 is that it has a switch that lets you select if you want to drop the signal down -10, -20, or -30dB.
It's not the most elegant solution, but it will work well. If I were to set something like this up, I would likely use some Kino Flo Tie Wraps to fasten all of this gear together, to keep it manageable.
Thanks for posting your question at B&H Insights!
Log in Register
Your B&H Photo login also works for B&H Insights! After your first login you will be able to create a username.