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What is optimal audio recording strategy?
Old 1 week ago
  #1
Here for the gear
 

What is optimal audio recording strategy?

I came from photography world where we use "expose to right" strategy. It basically means, getting maximum light to sensor for maximum bits in RAW file.

It makes me wonder if digital audio recording (from analog mic source) is same.

Max. input gain at expense of some noise.

Or keeping audio recording at "natural" levels.

I do not know how to exactly explain. At the moment, I do record at max. allowable input gain and later on bring everything back to natural level. In hope it records all faint sounds in nature.

Any suggestions, please?
Old 1 week ago
  #2
Gear Guru
 

What are you recording and for what purpose?

Normally you'll see that people with experience do not recommend recording "at max" levels. There's simply nothing to gain by doing so and you run the risk of clipping by getting close to 0dBFS. Instead analog audio devices tend to have a level that is "nominal" according to the manufacturer and at that point they should be working more or less optimally, and it won't be close to 0dBFS. The space between that average nominal operating level and 0dBFS is the headroom for any one given signal. So, your "natural level" is likely closer to their "nominal operating level", and that is fine.

Record at 24-bits and you should be fine.

- caveat -

If you're doing production sound recording for film/tv there's a chance you're using one of the newer devices that records to 32-bit float, and in those cases you can push levels higher, though I maintain it's still not good practice to do so.
Old 1 week ago
  #3
Here for the gear
 

Quote:
Originally Posted by mattiasnyc View Post
What are you recording and for what purpose?

Normally you'll see that people with experience do not recommend recording "at max" levels. There's simply nothing to gain by doing so and you run the risk of clipping by getting close to 0dBFS. Instead analog audio devices tend to have a level that is "nominal" according to the manufacturer and at that point they should be working more or less optimally, and it won't be close to 0dBFS. The space between that average nominal operating level and 0dBFS is the headroom for any one given signal. So, your "natural level" is likely closer to their "nominal operating level", and that is fine.

Record at 24-bits and you should be fine.

- caveat -

If you're doing production sound recording for film/tv there's a chance you're using one of the newer devices that records to 32-bit float, and in those cases you can push levels higher, though I maintain it's still not good practice to do so.
I document beauty of nature till humanoids destroy everything. I used to record at -6 to -12dB but I record 32b float nowadays so clipping doesn't bother me anymore.

I simply set something universal...go away...sometimes comes bird too close and it clips recording (I simply bring it down). It seems to work with this 32b float theory.

What I meant, if you record too low gain and then increase gain in post-processing...I guess it simply interpolates/guesses data and it can distort something. What is not there is hard to reproduce (at least in photography)

But optimal input gain can be reduce with no losses because it simply recalculate real data...if I understood all correctly
Old 1 week ago
  #4
Quote:
Originally Posted by sn1p3r29a View Post
Max. input gain at expense of some noise.

Or keeping audio recording at "natural" levels.
Sorry, but I think it's hard to understand what you mean with those statements.
Max input gain typically results in lowest possible noise, if you mean white noise, "hiss". Or do you gain so much that the noise you refer to is distorsion?

And what does "natural levels" mean? The word level typically just means volume. And changing volume doesn't change the nature of the sound, it just makes it louder or less loud.

Maybe it would be useful if you explain your setup a little bit more.
Old 1 week ago
  #5
Gear Guru
 

Quote:
Originally Posted by sn1p3r29a View Post
I document beauty of nature till humanoids destroy everything. I used to record at -6 to -12dB but I record 32b float nowadays so clipping doesn't bother me anymore.

I simply set something universal...go away...sometimes comes bird too close and it clips recording (I simply bring it down). It seems to work with this 32b float theory.
Yeah that actually seems like a pretty textbook example of the benefits of recording to 32-bit float and just lowering the "overs" in post. Seeing your use-case I probably wouldn't change that.

(please always state what you're referring to when you write "-6" though - average or peak)

Quote:
Originally Posted by sn1p3r29a View Post
What I meant, if you record too low gain and then increase gain in post-processing...I guess it simply interpolates/guesses data and it can distort something. What is not there is hard to reproduce (at least in photography)

But optimal input gain can be reduce with no losses because it simply recalculate real data...if I understood all correctly
Honestly I think you're overthinking this a bit. The best answer is going to be to contact the manufacturer of your recording device and ask them this question (unless it's in the manual).

The reason I'm saying this is because Sound Devices for example has their own way of 'mapping' the input signal within that 32-bit float. So I don't really know what that means in practical terms specifically for that device.

Generally speaking I don't think thinking about it the way you do is the right way to understand digital audio since there are some differences between image and audio that make what seems like intuitive comparisons actually not really that great.

If you actually record "too low" then what can happen is that the input signal is too low relative to the self-noise of your equipment, and so when you raise it in post you raise that noise. I don't think it's so much about "interpolation" or "guessing" or something. The sound is sort of there, but covered by noise, and you can't really extract it easily... if it's "too low".
Old 1 week ago
  #6
Quote:
Originally Posted by sn1p3r29a View Post
I document beauty of nature till humanoids destroy everything. I used to record at -6 to -12dB but I record 32b float nowadays so clipping doesn't bother me anymore.

I simply set something universal...go away...sometimes comes bird too close and it clips recording (I simply bring it down). It seems to work with this 32b float theory.

What I meant, if you record too low gain and then increase gain in post-processing...I guess it simply interpolates/guesses data and it can distort something. What is not there is hard to reproduce (at least in photography)

But optimal input gain can be reduce with no losses because it simply recalculate real data...if I understood all correctly
Maybe disregard my last post. What you wrote now explains it a bit.

Increasing gain inside a DAW does not change the nature of the sound at all. It's just about adding values equally to every sample point in the waveform. Really, really simple maths .

But (and maybe stating the obvious):
It also adds values to the inherent noise that comes from you microphone and preeamp. So noise will increase as well.

My guess is that capturing nature like that always will be a compromise. The dynamic range of nature sounds is probably larger than that of most analog equipment.

Best of luck in your endeavour!
Old 1 week ago
  #7
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Quote:
Originally Posted by thedberg View Post
Sorry, but I think it's hard to understand what you mean with those statements.
Max input gain typically results in lowest possible noise, if you mean white noise, "hiss". Or do you gain so much that the noise you refer to is distorsion?

And what does "natural levels" mean? The word level typically just means volume. And changing volume doesn't change the nature of the sound, it just makes it louder or less loud.

Maybe it would be useful if you explain your setup a little bit more.
What I meant is that waking up forest starts with barely 30dB ambient sound level and gradually goes to peaks at 60dB.

It means that audio recorder gain is almost every time +76dB

Of course it brings up all the device natural noise and picks up also some unwanted civilization noises. But when you go to "natural" volume with some EQ post-processing...it all disappears
Old 1 week ago
  #8
Here for the gear
 

Thanks guys,

I understand concept of optimal signal to noise ratio. I have noticed that it is usual issues with cheap mics and "silent" nature.

I started with Lom MikroUsi Pro mics. They have 20dB self-noise and annoying high frequency noise. On other hand, my "binaural" rig with two Audio Technica AT4021 cardidoids is another level...they have 14dB self-noise.

I have heard from my master that there is some hardcore mics with so low self-noise...they cost around 6000USD and need own 110V power supply.
Old 1 week ago
  #9
Well. I don't do nature recordings so I think any more comments from me would be just adding misinformation.

But good luck!
Old 1 week ago
  #10
Gear Nut
 
MandoBastardo's Avatar
Might get better answers by asking over in the Remote Forum (All Things Technical).

Sennheiser's MKH 20/30 are RF condenser mics that are much more immune to humidity than normal condenser and are exceptionally quiet - rated at 10dB self noise. Well regarded for outdoor/location recording. Under $1400 each.
Old 1 week ago
  #11
Gear Guru
 

Quote:
Originally Posted by sn1p3r29a View Post
I came from photography world where we use "expose to right" strategy. It basically means, getting maximum light to sensor for maximum bits in RAW file.

It makes me wonder if digital audio recording (from analog mic source) is same.
In the days of tape, there was systemic noise from the recording media itself. Even if you did not plug in a mic - if you recorded "nothing" - there was still X amount of noise on the playback. That made maximizing the recording levels a useful strategy. But a modern digital recording system is about as quiet as it gets. "Maximum bits" is a concept that went out with 16 bit ADAT recorders. Or should have.

The preamps - the analog components in your equipment - will be straining to produce a "maximum" level in your digital recorder. This may create harshness or even distortion. Yet it won't help 'drown out' the noise, because the noise is not coming from the recording system. It's already present in the mic and preamp.
Quote:
What I meant, if you record too low gain and then increase gain in post-processing...I guess it simply interpolates/guesses data and it can distort something. What is not there is hard to reproduce (at least in photography)
You guess? You would have to be recording insanely low to have that as a problem. With 32 bits, and a 'natural' level, you have plenty of resolution to turn it up later.

Quote:
Originally Posted by sn1p3r29a View Post
I understand concept of optimal signal to noise ratio. I have noticed that it is usual issues with cheap mics and "silent" nature.
Yes, blame the mics, not the "bits". The preamps are also a factor in the noise content of your recording.
Quote:
I have heard from my master that there is some hardcore mics with so low self-noise...they cost around 6000USD and need own 110V power supply
There are mics that are very quiet that are much more affordable. The Lewitt 540 is reportedly one of the quietest mics ever made and it costs about a tenth of that amount. Gets some good reviews as well.

You may need to do some research on the preamps. The preamps built into your recording device may not be the quietest around. You might get something outboard, but that may require a power source. I don't know who makes a portable recorder with the quietest included preamps but that's something Gearslutz is good resource for.
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