using smarteffector with 25mm fans on my delta. did a LOT of fiddling through the last weeks to somehow decrease noise- and vibration-level. different shrouds, fans and the like.
usually i had such a lot of noise and vibrations, i always had to bring my hotend-temp below 45°C to get reliable probing.
what i tried and dismissed during the last weeks:
- most thingiverse-shrouds don't take cfm/proper air-flow into account - they brake the flow that much down it doesn't make sense to mount them
- cfm-optimized shrouds for 40mm fans are to big for smarteffector
- 40mm fans seem generally to big for smarteffector (the difference 40mm vs diameter of e3d v6 heatbreak is to big - to much static pressure)
- 40mm noctuas (20 & 10 width) don't deliver enough pressure
- 40mm ebm pabst 40x40x10 at 24v doesn't deliver enough pressure
- non-direct, but remote air via silicone-tube: axial and radial fans don't deliver enough pressure - tried several versions (the fan's outlet-diameter has to be pretty close to the tube-diameter and also outlet - which renders fans useless unless one wants to use 25-30mm tubes)
so i stepped back to the 25mm ones - using 3 25x25x10 gostimes delivered with my printer-kit since about a year
- 25x25x8 ebm pabst are totally silent, but don't create enough pressure
- 25x25x10 gostimes don't deliver enough at 12v
- they certainly deliver enough at 24v (tried filament-fans with watertest - they stamped 2 holes 2-3mm deep into water-surface; hotend with finger on fins of heatbreak)
- combined with a stepdown - buck-converter - one can limit noise and vibrations by going down from 24 to about 20v - with lot less airpressure
effective against vibrations/noise:
- good bearings
- have fan blow freely (cfm-optimized shrouds; putting the fan under to much static-pressure stress introduces force, vibrations, noise)
- soft flex-filament spacers - where applicable - might help a little bit (but fixing the cause - non-free airflow - has a much bigger effect)
what i also found out: my magballs interfere quite a lot with the heatbreak-fan-motor. infact they can brake him down to a stall. burned one fan this morning. with quite a bit of fiddling found out that the rods magnets can brake down the fan significantly on wrong polarity. one can check it by bringing the magnet from the distance towards the ball while looking at the fan. if the fan's visually and noise-wise braking, turn the rod around and try with the other end. with 2 rods mounted in one corner - 1 being wrong polarity - my fan came to a halt.
that might not directly answer the above question, but perhaps give some ideas.