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Author Topic: Recording with gear using 32bit Float - The Recording Experience  (Read 4536 times)

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Offline voltronic

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Re: Recording with gear using 32bit Float - The Recording Experience
« Reply #15 on: October 29, 2019, 06:56:52 AM »
Heh, well that's peaky stuff!  Here I had to add considerable amounts of HF boost for it to sound "right" but that's probably down to my 70 year old seriously shot ears.  BTW it played just fine in "VU Player" - I wasn't sure whether the 32 bits might cause a problem.  (And right now I'm updating from version 2.49 to version 4.8!)

The highs come through pretty strongly for me on my HD650s, particularly the snares and the vibes.  It does sound like the band is a considerable distance away, because they are.  But my setup was in the place you are supposed to listen to these shows.  They are trained to play to the press box, which I was right next to.

In the past, I have used my little Naiant omnis for these shows which have a treble bump - that compensates for the HF loss at distance.  I suppose I could use my DPA 4061s which would be even better with their short boost grids, but I never want to risk losing them as I'm racing to set up on the stands.  I also would need to get much better windscreens for them - sometimes there is serious wind at these shows, particularly up high.
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Offline shijan

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Re: Recording with gear using 32bit Float - The Recording Experience
« Reply #16 on: October 29, 2019, 07:49:56 AM »
I add track gain (volume) +20 db.
Screenshot shows slightly different setup. I normalize item and add +18db gain to track. And use Limiter on final master track. Sort of extreme test, but you can do the same with 24 bit source if it was not clipped during recording.
32 bit allow to record accidental overloaded sounds, and bring clipped data back in post. Some Sound Devices tests explain that 32 bit also less noisy when you try bring back ultra quiet data, but i am afraid no one will hear differnce in real life, because that difference located lower than microphone self noise and ambient noise. In most real life situations if you adjust preamps record track without clipping 32 vs 24 will be the same.
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Offline Gordon

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Re: Recording with gear using 32bit Float - The Recording Experience
« Reply #17 on: October 29, 2019, 09:13:34 AM »
My guess shared file was unprocessed 32 bit source, it needs to be adjusted and compressed. Same goes to 24 bit recordings captured with low levels to avoid clipping.
Here is my very basic attempt to adjust file in Reaper. Source file gain was boosted +20, and Limiter was applied to Master Track. As a result - loud, but same time distortion free output.
https://i.imgur.com/jorv9zz.jpg
https://www.dropbox.com/s/3nxd6g3k4xij5qp/191026_002excerpt-processed.mp3?dl=0

Surely you mean +2, and not +20 dB?  The peak value of the excerpt I posted is between -3 and -2 (don't remember exactly, and not at that PC).

yea left channel is -2.99 peak and right is -2.04
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Offline Ozpeter

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Re: Recording with gear using 32bit Float - The Recording Experience
« Reply #18 on: October 29, 2019, 09:15:39 AM »
32 bit float will not change any of the old arguments regarding limiting.  Some take the view that any change in the overall dynamic range of an acoustic (usually classical) recording is heresy, and those that take that view will be delighted by the very lifelike dynamic range these new recorders will offer.  Others take a more pragmatic view, that most people's listening spaces have noise levels such that low level signals will disappear in the room, or that high level signals will cause the neighbours to complain. 

My own concern in days gone by was that I often came home with recordings which might have one or two peaks which were considerably higher than all the rest of the recorded material - sometimes more by accident than design.  If the recording was circulated uncompressed, it would sound pretty low level almost all the way through.  But if I did use a limiter, it would be a very fast one which only affected the smallest number of samples possible, and which would be undetectable by the listeners.  It would leave 99.99$% of the audio unchanged.

An example of the kind of "accidental" peak I'm thinking of would be where the last chord of a mighty organ work would build up in a cathedral, the level being compounded by reverberations and pressure waves bouncing around the building, although the level originating from the instrument wasn't varying.  Or when a timpany player got a bit more enthusiastic than the composer had in mind.  That kind of thing.

One thing is clear - these new devices offer a lot of choice over  levels  in post production and that enables recordists to make their own choices according to their own tastes.  Or the clients'.  That's good.

Offline voltronic

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Re: Recording with gear using 32bit Float - The Recording Experience
« Reply #19 on: November 01, 2019, 07:49:49 PM »
32 bit float will not change any of the old arguments regarding limiting.  Some take the view that any change in the overall dynamic range of an acoustic (usually classical) recording is heresy, and those that take that view will be delighted by the very lifelike dynamic range these new recorders will offer.  Others take a more pragmatic view, that most people's listening spaces have noise levels such that low level signals will disappear in the room, or that high level signals will cause the neighbours to complain. 

My own concern in days gone by was that I often came home with recordings which might have one or two peaks which were considerably higher than all the rest of the recorded material - sometimes more by accident than design.  If the recording was circulated uncompressed, it would sound pretty low level almost all the way through.  But if I did use a limiter, it would be a very fast one which only affected the smallest number of samples possible, and which would be undetectable by the listeners.  It would leave 99.99$% of the audio unchanged.

An example of the kind of "accidental" peak I'm thinking of would be where the last chord of a mighty organ work would build up in a cathedral, the level being compounded by reverberations and pressure waves bouncing around the building, although the level originating from the instrument wasn't varying.  Or when a timpany player got a bit more enthusiastic than the composer had in mind.  That kind of thing.

One thing is clear - these new devices offer a lot of choice over  levels  in post production and that enables recordists to make their own choices according to their own tastes.  Or the clients'.  That's good.

I don't have a problem with limiters in classical / acoustic recording, so long as they don't draw attention to themselves, and affects the bare minimum amount of the recording, exactly as you describe.

I have never been successful with this in my personal experience though, through a combination of my lack of skill and the limitations of the limiters in recording devices I have owned.
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Offline Ozpeter

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Re: Recording with gear using 32bit Float - The Recording Experience
« Reply #20 on: November 02, 2019, 08:54:45 AM »
Oh, I wouldn't dream of limiting at the recording stage - and of course with 32 bit float you don't need to.  I'm referring more to post-production - and to avoid putting a load of stuff here that is marginal to the topic, here's a link to something I posted way back which illustrates my personal approach and method (and the now unavailable VST I used to use).

https://www.gearslutz.com/board/showpost.php?p=5291625&postcount=32

Offline voltronic

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Re: Recording with gear using 32bit Float - The Recording Experience
« Reply #21 on: November 02, 2019, 12:17:57 PM »
Oh, I wouldn't dream of limiting at the recording stage - and of course with 32 bit float you don't need to.  I'm referring more to post-production - and to avoid putting a load of stuff here that is marginal to the topic, here's a link to something I posted way back which illustrates my personal approach and method (and the now unavailable VST I used to use).

https://www.gearslutz.com/board/showpost.php?p=5291625&postcount=32

I have often used limiting in post with classical recording; only when necessary of course.

Your procedure for testing VST limiters is very clever.

The "Soft Limiter" in Audacity is actually quite decent and simple to use.  I have often applied it to random percussive peaks that are far outside the RMS level of the concert, so that I can normalize several dB higher.
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Offline dallman

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Re: Recording with gear using 32bit Float - The Recording Experience
« Reply #22 on: November 04, 2019, 03:58:27 PM »
Observation: Zoom F6 vs SD MixPre6 II

Zoom claims that you cannot set gain on 32Bit Float, Sound Devices claims you can set gain on their MixPre6 (and other 32Bit Float models).

I am not sure if I can explain this and I am not claiming this is scientific, but my observation is that in reality they both do exactly the same thing in this regard. (I am not talking about sound, preamps or anything in that regard, just the use of gain for the MixPre6 II and Faders on the Zoom F6 on the wave form. Here is what I have observed:

On my MixPre6 II, I can set gain (pre-recorded level of sound), and there are a few ways to do this. The bottom line though is that it "feels" like there is a set sized file imprinted on my SD card that I can enlarge or shrink  in my post opened file, and it stays proportionally the same. That in essence means that the ratio of loudest to softest sound is what is being set by the MixPre, and I am enlarging or reducing that proportionally. If too big, it will distort, but then I can just reduce and it will be fine. How high or low I set my gain seems to have no (or little) effect on the final file. (we'll learn more as the samples become more prevalent, but this is what I observe)

On the Zoom F6, their claim is that Gain is preset  or predetermined and that you have fader (post recorded level of sound) control. Like the SD MixPre6 above, the file seems to have a predetermined ratio of loudest to softest sound, and the saved file on the SD card is determined by how loud or soft you set the faders. So gain is pre-set according to Zoom, but if I have my faders really low, I see a very small file when I look at it in post (I use SoundForge), and if I set my Faders high, I end up with a large (loud) file that gets printed on the SD card and observed when I open it in SoundForge. Again the ratio appears set. If it is too hot and distorted, I lower it and the wave file is fine and if it is too low, I add gain and the file proportionally gets louder.

So if I set gain on the MixPre loud and in the red, I get a huge file that may be distorted, but reducing gain (in post) brings me a wave perfect file. If I record too low, increasing gain (again in post), gives me a nice noise free clean file.

So if I set the faders on the Zoom F6 loud and in the red, I get a huge file that may be distorted, but reducing gain (in post) brings me a wave perfect file. If I record with my faders too low, increasing the gain (again in post), gives me a nice noise free clean file.

I hope this is clear, in essence they do the exact same thing. Now the ratio's between loudest and softest could be different (that is a different set of tests I suppose) but my point is that with these two 32Bit Float decks, setting the gain on the MixPre6 II or the faders on the Zoom F6 seems to do the same thing and yield the same results.
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Re: Recording with gear using 32bit Float - The Recording Experience
« Reply #23 on: November 04, 2019, 06:02:34 PM »
Intersting, thanks for the report. 
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Offline rick.lang

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Recording with gear using 32bit Float - The Recording Experience
« Reply #24 on: November 13, 2019, 02:45:15 PM »
When recording 32bit, I can set Gain using the menu controls on the MixPre-6 II.  I set it so that my level displays show me ‘normal’ looking audio volumes to monitor that I’m getting audio.  The knobs are Faders and don’t need to be used.

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Re: Recording with gear using 32bit Float - The Recording Experience
« Reply #25 on: November 13, 2019, 04:57:19 PM »
When recording 32bit, I can set Gain using the menu controls on the MixPre-6 II.  I set it so that my level displays show me ‘normal’ looking audio volumes to monitor that I’m getting audio.  The knobs are Faders and don’t need to be used.
You can set the knobs on the MixPre6, 3 or 10 II or older original MixPre 3,6 and 10 version so that the front knobs control gain. That is how I prefer it, rather than go into the menu. This has been well documented, custom setting, advanced setting for all else except gain set as basic setting. While it may be less important at 32bit, the more I use 3 2bit the more I seem to retain the habits I have always used, but with far less worry particularly at the beginning of a live set for an audience recording.
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Offline rick.lang

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Recording with gear using 32bit Float - The Recording Experience
« Reply #26 on: November 13, 2019, 05:10:29 PM »
Thanks for the tip!

Offline shijan

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Re: Recording with gear using 32bit Float - The Recording Experience
« Reply #27 on: November 24, 2019, 09:52:54 PM »
Some thoughts:

I done one more quick test with 32 bit sample files from SD website https://www.sounddevices.com/sample-32-bit-float-and-24-bit-fixed-wav-files/

1. I lower item volume to -150db (lowest possible volume in Reaper app)
2. I render one file as 24 bit and another as 32 bit.
3. I open both rendered files in Reaper and Normalize them back.

After Normalize rendered 32 bit file looked 100% like original
After Normalize rendered 24 bit file was crazy distorted.

Next i repeat test with source item volume lowered to -130db and -100db, but even so 24 bit file show very visible distortion after normalize.

Next i repeat test again and again and only with source item volume lowered somewhere to -60 -70db (at these levels waveform start to became rather visible), rendered 24 bit file starts looks more less like original after normalize. But i can still notice some tiny digital noise pattern artifacts if look very close on spectre image. Where is that truly safe limit in 24 bit file? It is fixed limit or smooth undefined limit? I don't know...

I see that 32 Bit Float allow to create really huge volume adjustments not only during recording but also during any other workflow steps and allow re-save truly lossless files 100% without any digital limits at all possible volume levels. So it seems like perfect archiving and editing format.

--------

For apps like DaVinci Resolve that can read 32 bit files but don't fully support 32 bit processing yet, the most universal compromise way is to normalize 32 bit files in Reaper, Soundforge, Izotope RX, and export with preserved Timecode in same 32 bit float depth.
In this case you can work with file in Resolve and same time you keep your actual 32 bit source data formally untouched, so it may be useful for other apps and processing plugins that operate in 32 bit float.

--------

You may notice in older Curtis Judd's videos he discover that the normalized sound character is slightly different at different gain amplification levels.
My guess it is not because A/D converters, but because analogue circuits inside microphone body itself.

In 32 bit at any gain level we always capture all possible dynamic range of microphone and so we can always digitally normalize it without any loss. So when we provide more gain to microphone we actually provide more voltage to its circuit and so internal electronic components inside microphone reacts somehow to this voltage and adds some specific character to the sound.
When we provide less gain/less voltage to its circuit, the internal electronic components inside microphone reacts somehow in different way to this voltage and adds some other character to the sound (less bass, less warm in that video example)

So probably with 32 bit recorder we can shape the sound of microphone by experimenting with different gain settings and find which gain will produce better sound on specific microphone model for specific needs.
« Last Edit: November 24, 2019, 09:55:24 PM by shijan »
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Offline jerryfreak

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Re: Recording with gear using 32bit Float - The Recording Experience
« Reply #28 on: November 25, 2019, 02:39:28 AM »
Some thoughts:

I done one more quick test with 32 bit sample files from SD website https://www.sounddevices.com/sample-32-bit-float-and-24-bit-fixed-wav-files/

1. I lower item volume to -150db (lowest possible volume in Reaper app)
2. I render one file as 24 bit and another as 32 bit.
3. I open both rendered files in Reaper and Normalize them back.

i would expect that as -150dB is below the resolution of 24-bit. same as if you rendered a file normalized to -100dB to 16 bit

Next i repeat test again and again and only with source item volume lowered somewhere to -60 -70db (at these levels waveform start to became rather visible), rendered 24 bit file starts looks more less like original after normalize. But i can still notice some tiny digital noise pattern artifacts if look very close on spectre image. Where is that truly safe limit in 24 bit file? It is fixed limit or smooth undefined limit? I don't know...

depends on the noise floor of your source recording. most mics have a self noise around 20 dB. in a studio setting its hard to get more than 80 dB of dynamic range. in a live concert its hard to get close to 50 dB over the crowd noise
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Offline rick.lang

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Recording with gear using 32bit Float - The Recording Experience
« Reply #29 on: November 26, 2019, 12:23:05 PM »
There’s nothing like experience to judge that as the ambient noise and the mic noise will vary.  I’d also appreciate some guidance on this from those who are recording indoors but not in a studio setting.

But if you don’t have the experience, this might just help.  The new MixAssist plugin for MixPre:


https://store.sounddevices.com/product/mixassist-plugin/
« Last Edit: November 26, 2019, 12:33:22 PM by rick.lang »

 

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