Adventures in Ender 3 Pro Noise Reduction (plus a Review)

I recently acquired an Ender 3 Pro. I was immediately impressed with how nicely organized everything is with it. Granted, the last printer I actually bought was one of the very first MakerBot kits. Anyway, I love my little Ender 3 Pro. As someone who’s done a lot of custom printer work, I couldn’t help but make changes, as much as I bought this machine specifically with the intent of changing nothing.

In my case, I decided to try to keep the machine looking fairly stock. I like mods that are subtle but high-impact.

Here’s a video I’ve made to largely convey the same noise reduction info that’s in this post, plus a bit of an overall review:

Here’s a quick list of the changes that I made that have substantially reduced the noise generated by this machine.

Parts List / BOM

Here’s a list of the parts I swapped in to my Ender 3 Pro for noise reduction. I’ve some some other mods too, but these ones are sound-specific. Note everything listed below can be sourced from a ton of places. I linked where I got mine, but you can get all this stuff from Amazon, or whatever works for you.

PartDescriptionQuantityCost ($CAD)URL
BigTreeTech SKR Mini e3 V1.2Control Board with ‘quiet’ stepper driver chips (TMC 2209)1$
BuckConverterAble to convert 24V DC in to other voltages, such as 12V for fans1 (needed), bought a bundle of them though$
2-pin JST Connectors (JST SM 2)Very handy for making changes, or replacing parts later, totally worth it. (Other JST connectors should be fine too, seems that the supply varies a lot, just use something of a decent gauge)4 used (bought a bundle)$, Here’s another Amazon option
Heat ShrinkFor insulting joined wiresMaybe 30cm worth?Maybe $1 worth?I had them already. Here’s something similar – Link.
12V Noctua 40mm x 10mm fan (NF-A4x10-FLX)Two 40x10mm DC fans, one for the hotend cooler and one for the control board cooler22 x $19 ($38)
12V Noctua 92mm x 14mm fan (NF-A9x14)Optionally for the Power Supply – this one required actual modification of the PSU1$
24V 40mm x 10mm blower fanReplaces the nozzle cooler, I’m really not convinced this one was actually quieter1$
92mm fan coverMy PSU replacement fan sat outside the PSU, so I made a cover to protect the blades. You can too1$
M3 bolts & nutsI used these to fasten my PSU fan to the PSU case4$

Stage 1: Reduce Stepper Noise

I promptly installed an SRK Mini e3 motherboard (from Spool3d) and was immediately stunned with how my steppers became nearly inaudible. I knew to expect this, and it still blew me away. A eventually learned that the 2209 stepper drivers can be switched between StealthChop2 mode (the default) and Spreadcycle. If you signal your control board to use Spreadcycle mode, then the steppers will be a lot more noticeable, but for the gain of probably better position accuracy.

The SKR Mini e3 1.2 is a drop-in replacement for the Creality board that comes with the Ender 3 Pro. It’s wise to snap photos of your board and connections before to you start unplugging.

Original Control Board:

SKR Mini e3 1.2 after installation:

Stage 2: Reduce Hotend Fan Noise

In order to install a 12V fan, I first needed a way of providing 12V. I decided to use the fan pin from the SKR board. I looked at the schematic and believe that it should be good to source enough current to run quite a few fans. So I overall decided to have that fan port drive a buck converter that I put 3x 2-pin JST connectors on. This gave me room for the hotend and control board fans, plus something else in the future (TBD). I decided to attach my buck converter by tapping M3 threads in to the control board casing. This was a terrible plan only because the casing’s walls are just to thin to effectively tap. I did get some purchase on my threads though, so I rolled with it.

Here are photos:

With 12V now being routed to my 24V hotend fan, it was now time to replace that fan itself. Also, be sure to get the polarity right, use a multi-meter both to check the voltage out of your control board and to adjust the output voltage of the buck converter to be close to 12V.

I have no photos of the hotend fan install, but the steps I followed were:

  1. Take off fan shroud
  2. Unscrew 24V hotend fan (not the blower on the side)
  3. (Ensure power’s off), push back the braided sleeve, clamp it back in place to hold it out of your way, cut the fan wires, leaving plenty of room to strip wires.
  4. Solder in JST 2-pin socket connector on the machine’s hotend fan wires, use heatshrink, of course
  5. Cut the wires on the Noctua fan, fold back the PWM wire, it won’t be used. Solder in the JST pin connector, with heatshrink
  6. Reassemble the hotend area.

You could stop at this point, as the machine will be a fair bit quieter. But, you can go on…

Stage 3 (Optional): Replace the Control Board Fan

With the buck converter in the control board’s case, attaching another 12V Noctua fan is simple. Not much explation needed here. Go for it, or don’t.

Stage 4 (Optional): Replace the PSU Fan

First off, I’m not responsible for your safety or property. So, you know, you own that. Secondly, doing work inside of AC power supplies can potentially be deadly. So, enter your PSU at your own risk. I’m personally fairly comfortable with electronics, but I still tread really carefully inside of PSUs. I have been shocked before and it sucks a lot.. And again, if you’re unlucky enough, it’ll kill you. So.. You’ve been warned (it’s concerning how many things I see on PSU mods that make no mention of there being risk).

In my case I was surprised to find my PSU’s fan is actually a 12V fan. This made replacing it not require another buck converter. Of course, installing another buck converter is no big deal, so for those of you with 24V fans in your PSUs (which is common), you’ll have to figure that out, it would be similar to how the other buck converter in this post was handled.

Before much of anything
Inside my PSU before doing anything
After drilling out holes for screws, airflow and cabling
Holes.. Some people like to cut everything away to allow more air through. I like having the high power guts fairly enclosed. If the PSU explodes, I want a cage to keep the guts inside. You do you, I do not care to debate the topic.
Here are the new fan’s wires, with the white cable protector from the stock fan added. I assume these are thermally protective to the wires. I’m not sure, just a guess.
Closing up the PSU
Fan installation complete
PSU fan in action

Stage 4.1 (Optional): Install PSU Fan Shroud

I CADed a shroud for my PSU fan mod, cause I didn’t want the blades getting damaged. Also, I saw an incredible video that explained how directing the air in to the fan can actually substantially improve the fan’s performance. Here’s a link to my shroud I designed in Fusion360. It took me quite a while to figure this out:

Download STL file Classic Styled 92 x 14mm Fan Cover, sudoreboot
Model of fan shroud
Fan shroud installed