Re: Print fan wine noise at lower than full speed
There is an open pull request for this here https://github.com/prusa3d/Prusa-Firmware/pull/1193
It sounds from the comments like it's not trivial to merge because going above 325hz affects the quality of the fan RPM measurement and might lead to issues detecting a stalled fan.
Maybe lowering the pwm would be another alternative? I think it would be less annoying if it was down in the 30-50hz range.
After I upgraded the extruder as part of my MMU 2.0 installation the fan PWM setting for PETG is unbearably loud, I never noticed it before the upgrade so I wonder if it purely a mechanical resonance difference or if the PWM got louder in firmware 3.5 too.
Re: Print fan wine noise at lower than full speed
https://github.com/prusa3d/Prusa-Firmware/issues/460
The link is nearly at the end of the discussion and titled "Firmware 3.5.1 with 1193 merge MK3.zip"
I just applied the updated firmware. The high pitched whine is gone, it is now a much more silent low-frequency rattling. Though I'm not sure if that might be a mechanical problem of the fan and not related to PWM at all.