Is it really a good test to operate PWM fans under voltage though? Some bearings, such as Sunon's magnetic levitation bearings, have to operate at 12 V or near-about to get the effect.
Honestly Sunon mag levs are kinda rare and there are ones that can be run under voltage control. Usually they state it as the start up voltage. But yes mag levs can be fussy. They are kind of the exception as most either run some variation/combination of sleeve, sealed sleeve(FDB), or ball.
I know they actually bin fan motors based on the speeds they run. It's one of the reasons higher speed versions of exactly the same fan(besides max speed) tend to cost more.
Yea no use. Voltage control is not really the holy grail. He has a coincidence with lower voltage the switching noise becomes more silent too as the amplitude gets smaller obviously.
Well I have to admit that there are really badly designed motor drivers. Nidec one is trully a great one. You have to take apart the cover and measure what is really electrically happening there. Yea... it sucks.
And for example, take Sunon maglev and put a 100uF capacitor across the 12V line directly at the point where wires are soldered(I put a slim tantallum usually). I put them in power supplies, and those are voltage controlled and got noise issues at idle low RPM(Volts). And run it from 5V and up with and without the cap. It will tame down the motor noise as the shape and slope of the controlling motor PWM will get as it should be from a triangle, saw like shape to meander. Well just for the lulz... you know isolation boredom...
I was more in line with you don't always have PWM to control these fans and it's good information to have. There are many where the PWM version is superior. Guess it's a question of if it's an easy thing to test on his fan controller. On my Aquero 6, I could test minimum voltage in under a minute easily.
That's actually really interesting. It's like why they add a capacitor to the fan in those cheap and sketchy hot air stations.
Gotta pass the time somehow, right?