Audio levels not matching

I am recording audio to a Sound Devices 702. If I record a test tone (-20db tone) and bring it into FCPX, it does show accurately at -20db on the meters.

If I record my voice humming at -20db, it comes into FCPX showing around -25db on the meters.

So basically all my recorded dialog ends up being several db quieter than it appears on the 702. I have tried all the ballistics metering and it's the same across the board.

Perhaps this isn't entirely an FCPX question, but can anyone guide me to where the discrepancy lies? I am not an audio pro, so I'm not 100% comfortable with all the audio tech stuff. I can get good sounding dialog, but it's driving me nuts that the signals don't match. I feel like I'm missing a few db of headroom that would be nice to have to keep that noise floor down.

Here's a little video I made to illustrate the issue:

vimeo.com/207398655/96bc78140b

My guess is that you only recorded one channel with the lav mic and are playing it back with two channels. You'll lose at least 3db when doing this. If you left the mono channel on mono (left channel only) how does it play back? Or does your device automatically lay it down on both the left and right tracks even if it's just getting input on the left channel? If that's the case then it's your device.

Mindbend.

I've noticed this as well. I use a Sound Devices 633 and even though my levels are perfect on the 633, my audio always seems to import on the quieter side. I can't remember where I saw or read about this, but it may have something to do with the difference of "meter ballistics" between our SD and the meter in FCP X. Or if on import FCP is "normalizing" the audio, and if that makes any difference. I am not an audio expert, but I hear you.

I'm hoping someone can clarify this too.

Redifer wrote: My guess is that you only recorded one channel with the lav mic and are playing it back with two channels. You'll lose at least 3db when doing this. If you left the mono channel on mono (left channel only) how does it play back? Or does your device automatically lay it down on both the left and right tracks even if it's just getting input on the left channel? If that's the case then it's your device.

Yes according to pan law 2 channels of mono audio, left & right, will sound 3dB louder than one channel if it were panned to centre.

This could have something to do with the way Sound Device monitors as well.

For all intents and purposes you can add a gain plugin to your audio to make up the difference and mathematically FCPX's summing engine will be no worse off. What does matter, however, is getting as much difference as possible between background noise and unwanted audio and the stuff you do want. This comes down to trying to capture the sound as loudly as possible without adding to your noise problem. The biggest factor there is mic choice and placement and isolating your takes from unwanted audio as much as possible.

All things being equal, it is much better to do a clean gain boost inside Final Cut or an audio editor, than it is to boost your audio with a noisy camera pre-amplifier... But hey, that's why you use the SoundDevice right!!

In my experience you can usually crank these devices up to between 2 or 3 o'clock without adding to much internal noise. The other thing I'd saddest is recording at a high bit depth as well like 24-bit. This should help provide separation between wanted and unwanted audio.

Getting back to your metering dilemma, check the settings of your device, it may have a few choices for calibrations. However, you don't have to obsess over this too much. The main thing is to record loudly as you can without clipping or without adding other noise.

Thanks, this was very helpful. I did confirm that my levels changed when changing from stereo to mono. It's still not 100% accurate to what the 702 meters showed, but it's a lot closer.