Thu Sep 05, 2019 4:12 am
Dimitri - thank you for posting that comment from Mr. Satz. He knows far more than I do, but he concludes with the same thing I have been thinking about with this new generation of relatively low-cost recorders: "But it all comes down to the actual implementation." (and the pre-amps!)
But one thing I notice in his comment is that he is talking about "gain-ranging A/D converters" rather than the dual A/D converters that I think both Zoom (in the F6) and Sound Devices (in the Mixpre Mk II units) are putting out. I can see how an auto gain-ranging device would "pump" noise up and down with the overall signal - it's acting as what it is called and auto-gain device. But if I am understanding what Zoom and SD are releasing, they have dual A/D converters for each pre-amp/channel - so one handles the low volume and the other the high volume with some sort of digital cross over where they overlap.
Just like dual-native-ISO light sensors, the upper range A/D converter will add some of its own noise to the signal, but just like dual-native-ISO sensors, the end result should be much better overall noise performance. (Plus, the A/D converters contribute much less noise than the camera sensor in my comparison, or for that matter the mic, cable, or pre-amp.)
As Mr Satz wrote, it's all down to implementation. If I understand correctly, the dual range A/D converters will work better than the auto-ranging systems for noise, but all the other links' limits will come into play. The mic has a dynamic range limit (though this is likely to be the strongest link in the chain.) And the pre-amp has its own upper and lower limits. I suspect it will be down to the quality of the preamp - the lower range A/D converter will capture the pre-amp noise along with the faint signals, while the upper range A/D converter will capture the pre-amp clipping without it's own digital clipping (assuming the mic doesn't clip first.)
Zoom has made the more bold claim, if I recall correctly - that the system in their recorder will always exceed the dynamic range of essentially any mic. I'm skeptical given the range of mics out there. If we don't have any control over pre-amp gain at all, then that makes me suspect they're running it at pretty low gain, so that no one will ever claim the pre-amp clipped. That means a trade off at the low end, particularly for less sensitive mics.
But at this point, all I'm doing is speculating. I look forward to both companies releasing their products, explaining in more detail how they actually work, and most of all, testers who know a heck of a lot more than I do actually testing them and telling us what they think.