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Author Topic: Zoom F6 (32-bit float equipped)  (Read 15145 times)

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Offline EmRR

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Re: Zoom F6 (32-bit float equipped)
« Reply #15 on: April 14, 2019, 11:14:56 AM »
I expect 32 bit to be useful at low levels, not really for high level gain setting.  32 bit does unchain you from any gain change constraints in post, you can crank up -50dBFS signals with little/no penalty. 

If you’ve got some imaginary input with supersonic specs. Just because you’re recording at-50 dB  doesn’t mean the noise floor is not still around 115. No advantage over 24 bit

You are right the analog noise floor remains the same regardless of 24 or 32, and it may be poor/average in this product.  If they are deriving a pretty clean 32 bit word (remains to be seen), the bottom bits are so far down that you can set gain after the fact, which may be better than what the onboard preamp contributes if cranked up.  Digital gain on a low level signal at 32 bit float with a 32 bit word may contribute less noise than a Zoom preamp cranked way up.  It may be the same, but more free of dither noise artifacts for dialog production in film/TV.  It's apples to oranges in lots of ways, but it may give a bit of commercial advantage over the production costs of quieter analog input stages while easing the requirement to worry so much about input levels. 

Typical ambience in a quiet room with most microphones is generally enough to mask most analog noise floor anyway, unless that noise floor is significant.   Most new recorders have pretty respectable noise floors. 

My MOTU 16A converter (24 bit with 32 bit output bus, +24dBu max input = 0dBFS) shows a noise floor no worse than -137dBFS (-113dBu) at 16kHz in an analog wired loop test from DA to AD, -143dBFS (-119dBu) at 4kHz where the ear is generally most sensitive.  It appears to be defined by the dither curve, when you look at various sampling rates up to 192kHz.  That compared to the Zoom F8n at least is a much bigger difference, and easily trumps 24 versus 32 for practical purposes, and that basically agrees with your point. 

I had an F8n (interface mode) and the 16A connected as an aggregate device into a DAW, and used a Sytek MPX-4Aii driving the 16A, set the Sytek for max gain and matched the F8n gain to it.   Then looking at the noise floors, the F8n was 2.5dB to 1.2dB noisier from 1kHz to 16kHz, but 4.5dB at 250Hz, 7.5dB at 100Hz, and 10.5dB at 30Hz. 

What I haven't done yet is measure noise comparisons at minimum gains, will have to do that. 

Anyway, spitballing here, lots of contradictory 'what ifs' and unknowns.  I definitely don't feel any need to upgrade, but it may be something to look forward to when the time comes.   
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Offline Paul Isaacs

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Re: Zoom F6 (32-bit float equipped)
« Reply #16 on: April 16, 2019, 02:34:39 AM »
FWIW... Microphone self noise and mic preamp noise make the 32-bit v 24-bit debate sort of irrelevant. 24-bit is more than big enough a container to handle the dynamic range of any real world sound and provides all the resolution and accuracy you need even when capturing extremely low level analog signals. If you have a low self-noise microphone plus a high quality mic preamp, record something at low level e.g. peaking to about -50dBFS and normalize to -0.1dBFS. The difference between 32-bit and 24-bit will be negligible. The only difference is that with 32-bit, you've recorded 30% more data for no additional quality.

Offline jerryfreak

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Re: Zoom F6 (32-bit float equipped)
« Reply #17 on: April 16, 2019, 04:12:12 AM »
FWIW, this show was recorded 10 years ago without a preamp... schoeps CMR>battery box>AD2K @ 24/96 (AD2K is a great design, but 20-year old tech at this point. 117 dBA dynamic range with it 'wide open' at +14dbU=0 dBFS)

levels peaked around -30 dBFS and was normalized in post with no other processing, EQ, or noise reduction

https://www.youtube.com/watch?v=vcACDQv2x9I&feature=youtu.be&t=548

if you need to record at levels lower than that maybe time to rethink your setup. that setup above was designed to be minimalist and bypass additional components, but realistically, when you get to signal levels lower than that, the self noise of components starts to creep in and become significant, regardless of the word depth you end up capturing at the end.

conceptually with the dual ADCs they can tune to a wider gain range (one mic level, one line level), but in reality thats still somewhat automating the level setting process

there are tons of pres from 20 years ago that had 70 dB or more of clean gain, as paul said when recording at levels that quiet, the mic noise becomes real apparent

maybe theres something im missing, i get the benefit of a wider input range but dont see it as a practical feature id use
« Last Edit: April 16, 2019, 04:30:11 AM by jerryfreak »
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Offline EmRR

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Re: Zoom F6 (32-bit float equipped)
« Reply #18 on: April 16, 2019, 10:56:17 AM »
I don't really see anyone here needing this 'feature'.  I'll be curious to see some real data showing practical benefits. 
Mics: DPA 4060 w/MPS 6030 PSU/DAD6001/DAD4099, Neumann KM 131, KMR 81i, Oktava MK 012, Sennheiser MKH 105, MKH 20, MKH 30, MKH 40, MKH 800 TWIN, lots of other studio appropriate choices
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Offline heathen

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Re: Zoom F6 (32-bit float equipped)
« Reply #19 on: April 16, 2019, 11:58:01 AM »
Speaking from the perspective of someone who mostly records loud concerts where the noise from the crowd alone is probably 60-70 dB, I think a feature that's more important than 32-bit is the number of channels, and this has two less channels than the F8/F8n.  While eight channels is likely overkill for most, I sometimes use that many (particularly when using the dual record function).

That said, I'm glad Zoom is pushing things.

If they really want to dazzle those of us here who comprise about 0.01% of their target audience, they could come out with a M10/R-05 size recorder that can serve as a true digital bit bucket.  Now that would be something.
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Offline Ozpeter

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Re: Zoom F6 (32-bit float equipped)
« Reply #20 on: April 17, 2019, 10:59:02 AM »
As I understand it, 32 bits or even 48 bits come in handy when digitally processing audio.  For instance, you can sum 8 channels together when each channel is peaking to zero, and the mix doesn't distort in the digital realm, though you might have to lower the master fader to avoid D/A distortion at the output.  On an anolog mixer you'd have to have each channel fader down somewhat to avoid distortion happening long before it gets to the master.  Maybe the mixer element of this recorder is working in 32 bits and they took the logical step of recording the 32 bits of each channel, rather than be dealing with say 24 bits for recording and 32 bits for mixing.  Guesswork...

Offline jerryfreak

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Re: Zoom F6 (32-bit float equipped)
« Reply #21 on: April 17, 2019, 09:36:25 PM »
almost all DAW software uses 32bit float for intermediate processing, as it reduces rounding errors in the final rendered product when multiple processing steps are involved
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Offline IronFilm

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Re: Zoom F6 (32-bit float equipped)
« Reply #22 on: April 17, 2019, 11:31:06 PM »
Speaking from the perspective of someone who mostly records loud concerts where the noise from the crowd alone is probably 60-70 dB, I think a feature that's more important than 32-bit is the number of channels, and this has two less channels than the F8/F8n.  While eight channels is likely overkill for most, I sometimes use that many (particularly when using the dual record function).

That said, I'm glad Zoom is pushing things.

If they really want to dazzle those of us here who comprise about 0.01% of their target audience, they could come out with a M10/R-05 size recorder that can serve as a true digital bit bucket.  Now that would be something.

Good point about needing more channels when using dual record.

Wish Zoom would push a firmware update for the Zoom F8n which allows it to do 18 track recording!

Thus then you'd have all eight channels recorded plus all eight at a safety level (at a pre defined level you could select in the menu) plus a stereo mix down. (which adds up to 18 channels in total)

Offline aaronji

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Re: Zoom F6 (32-bit float equipped)
« Reply #23 on: April 18, 2019, 10:55:26 AM »
Quote from: Dan Lavry in Tape Op #64
One should make a distinction between the "number of bits" and the "number of real bits." Take a 12-cylinder car where only 8 cylinders are connected to the drive shaft. Is it a 12-cylinder car or an 8- cylinder car? You can say it has 8 "real cylinders" plus 4 useless cylinders. Similarly, you can have 24 bits but how many of them are "connected" to the sound? There is no such thing as true 24-bit conversion and there won't be in my lifetime. I'm talking conversion bits here, which is different from processing bits. That's a big distinction. When you do processing you need more bits. Why? If each channel has a range from 0 to 1 million, then the sum of all the channels will range from 0 to 16 million, (requiring 4 more bits). Say you want to attenuate the range of a channel by 2. The "steps" are no longer whole integer. The smaller steps (quantization levels) also call for more bits. So for processing we want more bits to express both bigger numbers and smaller numbers. But at the end we scale back the number of bits. The extra bits served their purpose during processing, but the engine can never yield more dynamic range or less distortion than what was fed to it by the converters.

Mr. Lavry said that more than a decade ago, so maybe he has changed his opinion since then.  I kind of doubt it, though...

Offline WiFiJeff

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Re: Zoom F6 (32-bit float equipped)
« Reply #24 on: May 15, 2019, 08:37:57 PM »
YouTube discussion of what may be going on in the Zoom F6:

https://www.youtube.com/watch?v=NTuJ1fk3PsY

Julian Krause makes a very sensible guess at what may be in the F6 (if not, it's what should be!).

Waiting to hear more.

Offline voltronic

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Re: Zoom F6 (32-bit float equipped)
« Reply #25 on: May 19, 2019, 02:43:37 PM »
This NAB video from Gotham Sound with the Zoom rep has an interesting explanation on the benefits of recording direct from dual ADCs to 32-bit floating.  Skip to 2:20 for the part focused on that.
https://www.youtube.com/watch?v=VR-kvI7Gbl0

So the big deal isn't so much the 8 additional bits; it is the floating-point math, which means you don't reduce your resolution at the bottom end of the dynamic range.  You're not just looking at 8 more bits above 24-bit, as you would be if it were fixed point; the floating-point allows the full resolution at all volume levels. 

Here is a good explanation on floating-point numbers:
http://steve.hollasch.net/cgindex/coding/ieeefloat.html


A lot of the arguments I am reading here and elsewhere that say there is no benefit to recording in 32-bit float seem to make one or more of the following assumptions:

1. The 8 additional bits in a 32-bit audio file are useless, because 24-bit already exceeds the dynamic range of any mic, preamp, or ADC.

This is true when talking about the overall dynamic range, but how many bits of resolution are you able to actually use for the quietest sounds in your recording within a fixed-point file?  Also, once you introduce dual ADCs, that dynamic range widens significantly.


2. There are no native 32-bit ADC chips, so you have to quantize to 24-bit anyway which makes 32-bit float good for processing, but pointless for recording.

This was true until recently, but 32-bit ADCs are now available.


3. No one needs such ridiculously huge dynamic range, even if the hardware and software can do it.

Again, we're not just talking about the overall dynamic range, we are talking about the resolution available to the loudest and softest sounds in your recording.  Why would all of the DAW programs use 32-bit float (or 64-bit) for internal processing if there wasn't a benefit?
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Offline vwmule

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Re: Zoom F6 (32-bit float equipped)
« Reply #26 on: May 22, 2019, 01:24:26 PM »
« Last Edit: May 22, 2019, 01:32:31 PM by vwmule »

Offline lsd2525

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Re: Zoom F6 (32-bit float equipped)
« Reply #27 on: May 22, 2019, 02:16:20 PM »
Thing looks small
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Re: Zoom F6 (32-bit float equipped)
« Reply #28 on: May 22, 2019, 03:15:14 PM »
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Offline WiFiJeff

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Re: Zoom F6 (32-bit float equipped)
« Reply #29 on: May 22, 2019, 11:27:38 PM »
If you follow the "buy now" link on the Zoom US site to B&H, you see an pre-order price of $649 for the F6.

 

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