Exhaust Fan Silencer that was inspired by the Flowmaster muffler design. I know that it looks kind of hokey, but it's hard to argue with the results. The folks at Flowmaster really know what they are doing with muffler design.

This Fan Silencer is designed to maximize air flow while providing special baffling to trap the compression waves coming off of the fan.

Sound Reduction

This fan reduces the noise by around 7-20 decibels (depending upon measuring techniques). Please remember that decibels are not linear. In many cases this silencer provides a perceived noise reduction of 50%. WARNING: I am using a simple decibel app from my phone for measurements and mine, my friends' ears, and your comments for the perceived reduction.

Use on exhaust fans only

For those looking for an Intake Fan try https://www.thingiverse.com/thing:5177333

The design appears to have negligible negative effect on the PSU fan's ability to cool. Please carefully choose which model that you use. You do NOT want the exhaust air from the silencer pointing toward the air intake of your PSU.

Compatibility

This should be compatible with the Ender3/Ender3Pro/Elegoo Neptune series/Tronxy X5SA or any number of other clones using a 60mm exhaust fan.

Printing

Orient the model so the internal baffles are facing up. Use supports “Touching Buildplate”.

Installation

Remove the upper screw on your exhaust fan. Align the upper screw hole on the Flowmaster Silencer and reinsert and tighten the exhaust fan screw. Slightly rotate the Flowmaster Silencer so you can see and reach the lower exhaust fan screw. Remove the lower exhaust fan screw. Rotate the Flowmaster silencer so the final screw hole properly aligns and then insert and tighten the lower exhaust fan screw. WARNING: do not over tighten the screws or you may strip them out [and I know what I'm talking about].

HINT: use some electricians (or similar) tape to seal around the edges to really make it quiet. Make sure that you leave the exhaust hole open.

The Decibel Ranking of my Fan Silencers are as follows (lower score is better). Please keep in mind that the decibel scale is logarithmic and NOT linear.

Score 36

Fan Silencer Flowmaster

Score 38

Fan Silencer Muffler

Score 40

Fan Silencer v10:

Score 43

Fan Silencer v6

Score 65

Raw fan

As I lack sophisticated sound testing equipment, I'm using a Decibel measuring app on my cellphone. The cellphone was placed on top of the PSU with the microphone facing the side of the exhaust fan.