Topic: 32Bit Float recording - The Technical view

[grawk]

I have not read all of the above, but as someone who has been taping since 1971, I love the 32 bit world we have entered. Why? Because I have made great recordings. I have had no issues at all. The biggest difference is that I do not have to occasionally spend a inordinate amount of time leveling the first 10 or 20 seconds of a recording because it is too hot or too low. I have a few decks and do not at all mind going 24 bit when one of those makes sense, but using the same gear I have used for years, 32 bit is my choice. For me, how the end result sounds is what matters most. That said, I respect and admire all the dialog dissecting the respective differences in how we approach our passion.

exactly.

[GLouie]

I skimmed the Sound Devices 2016 patent for 32 bit (most of which is way above me) and note that it does describe 3 and 2 converter layouts, but noting it could be any number. I did not recognize any comment about the converter handoffs and noise control, but that could be me. I note that other manufacturers have to avoid infringing on their patent, so maybe SD understands the issue better and has the secret sauce in their patent. It would be nice to know if SD uses multiple converters in 24 bit mode, I haven't heard any issues and have not done much 32 bit.

On the clutch, I just prefer manuals as more fun. Today's automatics get better gas numbers and track lap times, but on the street that's not everything for me. I like road and machine feel, although most Americans apparently prefer automatics. I also don't use the phone while driving, even hands-free (legal requirement here).

As to the anti-theft aspect, I had an Integra manual for many years with a Club steering lock that was stolen 3 times, the last time driven 100 miles away and totaled. Integras were theft targets, so the thieves certainly were not stopped by a clutch or Club.

[unidentified]

I have not read all of the above, but as someone who has been taping since 1971, I love the 32 bit world we have entered. Why? Because I have made great recordings. I have had no issues at all. The biggest difference is that I do not have to occasionally spend a inordinate amount of time leveling the first 10 or 20 seconds of a recording because it is too hot or too low. I have a few decks and do not at all mind going 24 bit when one of those makes sense, but using the same gear I have used for years, 32 bit is my choice. For me, how the end result sounds is what matters most. That said, I respect and admire all the dialog dissecting the respective differences in how we approach our passion.

exactly.

Ditto, from a guy who started taping in 1972.

[datbrad]

Every car I owned from 1979 to 2011 was a manual. By that point years of driving in stop & go traffic keeping my left foot pressing the clutch most of the time had wiped out all the romance of a manual.

As for taping, the last deck I bought from Doug Oade is the Marantz PMD-561 with concert mode and the way he set the gain stages make it "almost" set and forget. He set the preamp gain so the overload point of the analog circuit and the clipping level of the A/D are matched perfectly. This allowed me to find a sweet spot to set the gain at the same starting position for 90% of shows that I never have to adjust again, or just once at the very beginning. Not the true "set & forget" convenience of 32bit float, but for a guy who used to make a dozen unecessary micro-adustments at every show I'm now comfortable only checking that the deck is running every now and then, which for me is huge.

[unidentified]

Every car I owned from 1979 to 2011 was a manual. By that point years of driving in stop & go traffic keeping my left foot pressing the clutch most of the time had wiped out all the romance of a manual.

As for taping, the last deck I bought from Doug Oade is the Marantz PMD-561 with concert mode and the way he set the gain stages make it "almost" set and forget. He set the preamp gain so the overload point of the analog circuit and the clipping level of the A/D are matched perfectly. This allowed me to find a sweet spot to set the gain at the same starting position for 90% of shows that I never have to adjust again, or just once at the very beginning. Not the true "set & forget" convenience of 32bit float, but for a guy who used to make a dozen unecessary micro-adustments at every show I'm now comfortable only checking that the deck is running every now and then, which for me is huge.

Concur with the point of about losing the romance of shifting in traffic, especially when stopping uphill is involved.  My German-built six speed automatic is wonderful.  As for taping, yeah, my Oade-modified Sony M-10s are also great in the regard that you mention.  No need for an external pre-amp and the sweet spot always seems to be at about three on the gain wheel, except in the quietest situations.  That said,  i still prefer the total ease of 32 bit Zoom F3, along with the security of the tight XLR connections. 

[Gutbucket]

Driving a four speed manual transmission around SanFrancisco for a few years was fun. Parallel parking on the steep hills was actually made somewhat easy by gravity.  Other drivers pulling up too close behind at a light on really steep inclines was worrisome though. For I while to activate the starter I had to crawl under, so I'd almost always just park on an incline, roll out and pop the clutch. My current manual has a hill-hold feature which makes it almost too easy- if the car senses it is on an incline, the brakes remain engaged for 5 sec after releasing them or until the clutch is engaged.  Almost no hill-skills required.

Here's an idea, the next round of 32bit float recorders could implement a feature that normalizes the 32bit float file after recording and writes a 24bit file from that.  No loss, and everything fits in a smaller, standard fixed-point format file.  Sort of a 24bit hill-hold manual in comparison to a 32bit-float auto-trans?  Yeah, reaching a bit there.

[goodcooker]

My current manual has a hill-hold feature which makes it almost too easy- if the car senses it is on an incline, the brakes remain engaged for 5 sec after releasing them or until the clutch is engaged.  Almost no hill-skills required.

I know this is still off topic but my GFs current ride is a 6 speed manual Mini Cooper and it has the hill brake thing. The first time we took a road trip and I was driving I had to stop on a really steep hill so I did the hand brake with the button pushed in thing to keep me from rolling back or stalling out and she just laughed at me. I learned in a three on the tree.

[carpa]

Back on topic....Given that the drawback of ADC switching might be a rise of noise floor, the point is that for some applications it may be audible, for others not.
Whatever the final delivery might be, i.e. 24bits 48khz,  is there at your opinion a difference between recording 48, 96 or even 192 khz in order to minimize the potential issues?

[voltronic]

I just pulled up the last 32-bit float recording I had made to find out if I could see and hear the problem being described.

Short answer: See? Definitely. Hear? Absolutely not.

See the attached screenshots from RX. This recording was 32fp/96kHz using my F6.

1. Hand Claps - You can clearly see the windowing as the noisefloor increases around the louder transients.

2. A Cappella - The three transients just right of center are accented syllables in the choir. You'll also see stray moments before and after where the converters switch.

3. Noise Zoomed - As it says on the tin. This shows why the added noise is inaudible - it's only showing up above 35 kHz or so.


So, is this still a concern from a sound design standpoint when captures will be pitched down, as shown in the video? Sure.

Is it a concern for studio or live music recording? Well, the noise floor is constantly shifting with the auto-ranging ADCs, at least on a Zoom F6. It's not just on the stray loud transients; it's happening frequently. But the noise is in a place that no one can hear. While I don't like that this is happening at all, it's not causing any problems in the audible range.

If anyone has a Sound Devices MixPre-II or one of the newer Tascam recorders that have auto-ranging ADCs, it would be helpful to compare their behavior.


EDIT: A user on GS has tested a Stagetec Nexus Compact and it does not do this. Maybe it's a Zoom implementation issue?
https://gearspace.com/board/all-things-technical/1425826-problems-32-bit-float-sound-design-pitching-down-white-noise.html#post16963512

[carpa]

Thanks @voltronic for posting your results. Most probably Stagetec or others have a better implementation…it is interesting though to read that Sound Devices seems to have fixed the issue via firmware update. This means that the issue was there before and that something has been possibly done. Don’t know wether Zoom will bother finding an improvement, should it be technically possible. Given the huge number of F series users- among which probably a lot of people recording and manipulating sounds- I can expect that some of all these complaints will eventually reach them and maybe lead to a fix.
The better behaviour with a SD788 is maybe due to a better hardware? It would be interesting to try the Zoom with an external preamp to tell how the overall tone of the recording changes.

[grawk]

the 788 works in a fundamentally different way.

[carpa]

From the manual and other statements made by Zoom it seems that the F serie uses two 16 bit converters; Zooms says that both in 32 bit and 24 bit mode the dual ADC is engaged.
This leaves to think that in 1 bit mode only one is working? If so it would be interesting to compare the spectral view of a 16 bit recording with a 32 bit one.  Not to conclude it's better to go back at 16, just out of curiosity.

[voltronic]

From the manual and other statements made by Zoom it seems that the F serie uses two 16 bit converters; Zooms says that both in 32 bit and 24 bit mode the dual ADC is engaged.
This leaves to think that in 1 bit mode only one is working? If so it would be interesting to compare the spectral view of a 16 bit recording with a 32 bit one.  Not to conclude it's better to go back at 16, just out of curiosity.

I'm not sure where you got this impression, but neither of the ADCs are limited to 16-bit. One is optimized for high gain; the other for low gain.

Both ADCs are engaged no matter what recording mode is selected. You can't choose to use only one, and that's a point addressed in the video.

[carpa]

I’m sure I read it somewhere but it’s probably not true. I was maybe tricked by the fact that Zooms says that both 32 bit and 24 adopt the dual adc, but no mention about 16 bit.

[GLouie]

YouTube poster has taken his video "private" for some reason, so hard for newcomers to see what the fuss was about;

https://youtu.be/y3431uljZ2k?si=I7I7qhsKK7TUo49s