Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)
are you using a condenser microphone of dynamic? The original audio board was sometimes guilty of introducing a high pitched (constant) tone / interference on the audio with phantom power engaged. If you are using a dynamic mic, you can disable phantom power and this may alleviate your issue. If you are using a condenser, you may be able to utilize and external battery powered phantom power supply and then turn of the phantom in the camera. I really would recommend using an external mic pre, though. Sound Devices MM-1 or MP-1 would be a vast improvement over the built in preamps. As far as setting levels, because you are not using a mixer, you need to be extremely wary of hot levels that could lead to clipping, so would use relative conservative values. Equipment, setup, and situation could make this figure vary drastically, but average levels from around -24dB to -18dB would probably be ok with peaks at -12. (all of these dB values are dBFs references) When I mix, since I'm constantly monitoring audio and ride faders, I'll go a bit more aggressive and shoot for -6 to -8dB peaks, but your guaranteed to clip if you just set and forget this way. (you'll probably want to check levels with a few tests and do a qualitative evaluation in a DAW or NLE before doing anything mission critical)
There are also other sources of interference such as stray RF. Some microphones are more prone to picking up interference than others. Make sure your cables are well shielded and properly terminated. Don't let anyone bring a cell phone within 12 feet or so of the mic, etc...
