Topic: New Zoom HxEssential recorders

[Ozpeter]

Just by way of updating the archive, and noting that a lot of assumptions were made in this thread about the 32 bit functionality of Zoom Hxe series recorders, here's the list of which ones are 'true' 32 bit float with dual converters, and those which are single 24 bit ADC devices feeding 24 bits into 32 bit float files.

H1essential - single ADC
H2essential - single ADC
H1 XLR - dual ADC (maybe the cheapest you can buy?)
H4essential - dual ADC for inputs 1 & 2, single for other inputs. 
H6essential - fully dual ADC

The "MicTrack" M series of devices are fully dual ADC

The F series configurations are well known already.

[rastasean]

Big thanks to you, Peter, for consolidating all this information and updating threads with the information you've been able to uncover.

Thanks for the reddit thread as well. You way to consider cross linking to /r/fieldrecording to expose the folks over there to your discoveries.
Many of those people buy recorders for recording nature and often look for newer recorders to get.
I think your discoveries will help people realize 32 bit float recorders need more detailed honest specifications published on them before buying them.

[Ozpeter]

Yes, I did wonder about linking in the field recorder people.  I'll do that shortly.  While I'm passing through here I should add that in the Reddit thread, one poster who seemed to know of what he spoke said that there is a way in which one ADC might be used to improve dynamic range captured, and that involved reducing the level in the preamp if clipping was about to happen, then raise it in the output from the ADC to compensate - I imagine very rapidly to ensure the manipulation could not be heard.  Well, if something clever is being done with one ADC I would have thought the manufacturers should be telling us about it in proud fashion.  Hmmm.

[Gutbucket]

See my post about compansion over in the 32-bit float thread this morning.

I suspect manufacturer's don't trumpet it's use in these recorders because it is essentially a cost saving work around to avoid the need for multiple switching ADCs, but will tend to be associated in user's minds with noise reduction schemes for analog tape and older analog wireless microphone systems that were not necessarily of the highest fidelity.

[Chilly Brioschi]

Yes, I did wonder about linking in the field recorder people.  I'll do that shortly.  While I'm passing through here I should add that in the Reddit thread, one poster who seemed to know of what he spoke said that there is a way in which one ADC might be used to improve dynamic range captured, and that involved reducing the level in the preamp if clipping was about to happen, then raise it in the output from the ADC to compensate - I imagine very rapidly to ensure the manipulation could not be heard.  Well, if something clever is being done with one ADC I would have thought the manufacturers should be telling us about it in proud fashion.  Hmmm.

ALC, aka Automatic Level Control, aka slow-response compression doesn't seem like a way to improve dynamic range at all.
Am I missing something?

Wait, what if we used dynamic, frequency-banded compression-expansion?     

[TheJez]

I suspect manufacturer's don't trumpet it's use in these recorders because it is essentially a cost saving work around to avoid the need for multiple switching ADCs

I'm not convinced that this approach would actually save costs, as it likely puts stricter tolerances and/or calibration work on the analog components. Such things increase production costs.

...but will tend to be associated in user's minds with noise reduction schemes for analog tape and older analog wireless microphone systems that were not necessarily of the highest fidelity.

You may be right about that. However, I don't think there is any proof or confirmation that this compansion technique is actually being used, right? So far, I don't think any manufacturer has been caught lying about their 32bfp products. They just smartly have been using the 32bfp hype to launch and sell new product lines. It was many of 'us customers' assuming 32bfp meant multi-adc... I'm glad that assumption is now out of the way.

[Gutbucket]

Just speculation.

The use of companding is one way to achieve extended dynamic range through a single ADC, using well understood and established tech.

ALC is another, if combined with a matching inverse ALC stage after the ADC that is aware of what the ALC is doing..

ALC, aka Automatic Level Control, aka slow-response compression doesn't seem like a way to improve dynamic range at all.
Am I missing something?

It doesn't have to be slow.  Long ago I wondered about an implementation which automatically placed a marker whenever the user made a change in gain, and also noted the value of the change.  That would allow for making an inverse manual or automatic level adjustment by the same amount at the marked points afterward on the computer, compensating for the gain adjustments made while recording.  The idea was simply to allow for manual gain adjustments as needed without that change in level effecting the resulting recording.  And as used that way it would be extending dynamic range, even if that was not the original intent.  But if automated, with the inverse correction being made digitally in the recorder itself after the ADC but before writing the data to memory, it could be used as a scheme for intentionally extending dynamic range through a less than state of the art, inexpensive ADC.   Conceptually, it is ALC combined with automatic correction for whatever changes in gain the ALC makes.

[Gutbucket]

^ A compansion scheme essentially achieves the same end result.  The difference is that a compansion scheme is constantly working in a way like an analog compressor and inverse expander. Whereas the "gain marker" scheme is discrete, noting each stepped change in gain.  I suppose a multiple switching ADC scheme might be made to work either way, with the essential difference being the difference in "integration time".