Yes, people are getting confused again, but it's mostly Zoom's fault for writing false information in an important part of the F3 manual. I'm hoping this post can finally put the issue to bed, so stick with me here.
First we need to clarify our terms:
Gain is the adjustment to the analog signal level pre-ADC.
Record level adjusts the digital level being written to the file, after it's gone through ADC and anything else that might be in the signal chain. Some people are using these interchangeably and that's muddying the waters. With that out of the way...
Gain (analog preamp level) is not adjustable on the F3, nor is it on the other F-series recorders when they are set to 32FP format. (I'm not sure that the SD MixPre-II works the same way. They may still allow gain adjustment in this mode - I might ask over in that thread.)
All of the F-series still have the ability to adjust
record level in this mode. It's not just an "appearance" thing; you are in fact changing the digital level being written to the file. The F6 and F8 manuals make this very clear, but the F3 manual is a hot mess when it comes to this point.
From the F3 manual:
NOTE
- The magnification rate can be set in 11 steps: ×1 , ×2, ×4, ×8, ×16, ×32, ×64, ×128, ×256, ×512 and ×1024.
- Be careful with the volume if you are monitoring the input sound with headphones, for example.
- Changing the magnification rate, even in the middle of recording, will not affect the recording level.
As several people have reported in this thread, the third point is false! The magnification level
does adjust the recorded level.
EDIT: Thanks to the test performed by @commongrounder, we now know that adjusting the magnification setting
while recording is underway does not change the recorded level; only the monitored output level.
The second point actually reinforces the fact that you are changing the post-ADC level. Otherwise if it was only affecting a visual display, the level in your headphone output would not change without you specifically adjusting the headphone output level, and they wouldn't need to warn us about it.
We can confirm that "Waveform Magnification" is actually a "Record Level" control by looking at the block diagram at the end of the manual. We can probably assume that the engineering team was involved in this diagram and that they actually know how the unit works, unlike the people who wrote the above excerpt.
There's a symbol under Waveform Amplification (Wait, I thought it was supposed to be Magnification??) that looks like a diagonal arrow on top of a circle - this represents a variable output. Notice that it is directly in the signal path, and that symbol appears in other areas where we know for sure that signal levels are being adjusted (Line Out, Headphone Volume, Alert Tone). The Waveform Display is shown to be a tap off of the main signal path.
So what we find is that the description of how the F3 works is not how the block diagram says it works, and the two places use different terms for the same thing, and one of those terms is misleading. If it really did work the way the description said, then that variable output symbol would not be in the signal path but instead would be shown after a branch off at Waveform Display.
So, bottom line:
Gain is fixed.
Waveform Magnification is actually Amplification and is a digital level adjustment.
Manual is bad.