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Recording low to avoid noise
We’re using a Zoom H5 with a boom mic to record interviews during an exhibit. For conferences, we connect the H5 directly to the venue’s mixing board. I hired an audio guy who recorded in -18 telling me that it will reduce picking up of ambient noise and mic’s self noise. But when I normalize it in post (bring up the levels) and compare it to my recordings at -12, I can hear no difference in ambient noise and/or hiss (I’m not an expert so there may be subtle differences that I’m not hearing). The -18db recording is still noisy when normalized in post. Is there a benefit in recording really low, like -18db instead of between -12 to -6? The only benefit I can think of is avoiding clipping.
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4 Replies
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Hello Clyde and welcome to the Cow Audio Forum.
Peaking on your recorder at -10 (with a few exceptions going up to -6 or so is what I shoot for.
If I’m feeding a camera with my mixer, I will calibrate the two. Set the camera for line level input. Set the mixer for line level output. Send tone to the camera and adjust the level on the camera to -20. My mixer goes up to +20 before clipping, so, in effect, I’m calibrating so that +20 on my mixer is 0dB on the camera.
I use a limiter on the mixer. It’s set to hold back any audio over +12. That leaves me 8 dB of headroom in case something unexpectedly LOUD happens and pushes through the limiter too quickly.
The camera meters show -8 + or – and that’s what you see on the file when you bring it in to edit.
My mixer to camera cable has a headphone return. I plug it into the camera headphone jack and adjust it for a good output. I flip a switch on the mixer and ALWAYS, ALWAYS, ALWAYS listen to the camera return when shooting. That way I don’t get surprised if something gets out of alignment; like you decide to shoot some b-roll between interviews and switch to your camera mic, then forget to connect the cable to the mixer when you do the next interview. Hey, how come it’s dead? Oh, I forgot to reconnect the cable! How come the levels are stupid? Oh, I readjusted them for the on-camera mic! I have to recalibrate the mixer and camera.
Any questions?
Regards,
Ty Ford
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[clyde villegas] “recorded in -18 telling me that it will reduce picking up of ambient noise and mic’s self noise. “
Simply no. The recording level has NO impact on the pickup of ambient or mic self-noise.Only using a microphone closer and/or more directional will reduce ambient noise by increasing the SNR (signal-to-noise Ratio) of the desired signal vs. the ambient noise. It is tedious, fiddly, and typical inordanitely expensive to artifically improve the signal-to-noise ratio after the signal has been recorded. Which is why appropriate microphone selection and proper application are MUCH more important than many people realize. It is always recommended to avoid reliance on “fixing it in the mix”.
Only the selection of a microphone with lower self-noise will affect the self-noise. The self-noise is “baked into” the design of the microphone. There is nothing you can do externally to affect self-noise. Except to feed an acoustically louder signal into the microphone to increase the overall SNR (signal-to-noise ratio)
The record level setting WILL affect the headroom you have while recording. If you are recording something with a predictable level, you can get away with a higher average peak level (perhaps -10dBFS). But if you are recording something that can be expected to have a wider dynamic range, then a lower average recording level will give you more protection against clipping from hitting full-scale.
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Recording audio without metering and monitoring is exactly like framing and focusing without looking at the viewfinder. -
Thanks Richard. Now I have more confidence to tell the audio guy that I’m right and he’s wrong 🙂
ut in omnibus glorificetur Deus
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Thanks for the advice Ty.
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