r/crboxes

Hi, I'm Max, an italian university student.
I'm writing my thesis and I need your help.

I'm researching air quality in domestic spaces — a topic that's rarely discussed, but affects us every day. This questionnaire will help me understand how people experience and perceive the air in their homes.
It only takes 6 minutes: little for you, everything for my research.

https://tally.so/r/WODlDj

Thank you!!

I spent way too much on this.. was a fun project tho!

I added an ESP32 device to control it with Home Assistant.

Also, lesson learned, don’t touch a running fan to figure out if it’s getting hot when it’s running full speed

Edit:

Here are some additional details.

For Next time - Adjust overall width to 19.75". The filter is very snug, I forgot to add a bit of room for play.

Component Size Type
Top: 20.25 x 11.5 .5" Plywood
Sides (2x): 25.25 x 11.5 .5" Plywood
Bottom: 19.25 x 11 .5" Plywood
Back: 25.25 x 19.25 .5" Plywood
Side Trim (x2): 23.5 .5" Quarter Round Trim
Bottom Trim: 19.25 .5" Quarter Round Trim
Header: 19.25 x 1.25 .5" Plywood
Internal Side Cleat (x2): 24.75 x .5 .5" Plywood
Internal Bottom Cleat: 18.25 x .5 .5" Plywood
Internal Top Cleat: 18.25 x .5 .5" Plywood
External Side Cleat (x2): 27.75 1/4 in. x 1/2 in. x Rectangle Moulding
External Top Cleat: 18.25 1/4 in. x 1/2 in. x Rectangle Moulding
External Bottom Cleat: 18.25 1/4 in. x 1/2 in. x Rectangle Moulding

Parts List:

20x25x2 MERV13 Filter - Filterbuy.com
Plywood (x2 or 4 ft x 4 ft if you can find it) - https://www.homedepot.com/p/ProWood-1-2-in-x-2-ft-x-4-ft-Birch-Plywood-Project-Panel-154153/203504316
Rectangle Moulding - https://www.homedepot.com/p/HOUSE-OF-FARA-1-4-in-x-1-2-in-x-4-ft-Basswood-Wood-Tinytrim-Rectangle-Moulding-TT12/202087496
.5" Quarter Round - Home Depot
5x ARCTIC P14 Pro PST - https://www.amazon.com/dp/B0DPX94PSL?ref=ppx\_yo2ov\_dt\_b\_fed\_asin\_title
XIAO ESP32-C6 - https://www.seeedstudio.com/Seeed-Studio-XIAO-ESP32C6-Pre-Soldered-p-6328.html
140mm Desktop Computer Grills (they come in a 4 pack unfortunatly) -** Case Cover with Screws, Aluminum Frame Ultra Fine Stainelss Steel Mesh, Black Color - 4 Pack : Automotive
1 Inch Black Desk Grommets - Amazon.com: Adyoney 6 Pcs 25mm / 1 Inch Black Desk Grommets, Easily Solve Cable Management Issues, Flexible Silicone Cable Cord Grommet for Table and Other Furnitures Hole Cover : Industrial & Scientific
12" PWM Fan Extension Cable - Amazon.com: 12" PWM Fan Extension Cable, 4-Pin PC Cable (30cm, 4pcs) : Electronics
12V to 5V 3A 15W Buck Converter Module - Type-C USB DC Power Adapter - Amazon.com: DIANN 12V to 5V 3A 15W Buck Converter Module - Type-C USB DC Power Adapter - Car Power Converter : Electronics
DC 12V 5A Power Supply Adapter Converter - https://www.amazon.com/dp/B01GEA8PQA?ref=ppx_yo2ov_dt_b_fed_asin_title
2 Pack Mini Blade Fuse Holder 18 Gauge Waterproof Pigtail Inline Fuse Holder with 5A ATM Fuses - https://www.amazon.com/dp/B08BLHCJBC?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1
33Ft Door Weather Stripping, (1/2in x 1/4in) - https://www.amazon.com/dp/B0DRFF39T3?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1
Speaker Grill Cloth - **https://www.amazon.com/dp/B0D6YKLTRW?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1
Everbilt Matte Black Piano Hinge (48", cut to fit) - https://www.homedepot.com/p/Everbilt-1-1-2-in-x-48-in-Square-Radius-Matte-Black-Continuous-Hinge-28926/314151008
Handle - https://www.homedepot.com/p/Liberty-Mandara-5-1-16-in-128-mm-Classic-Matte-Black-Cabinet-Drawer-Bar-Pull-P36131C-FB-CP/310240906
Latches (I had to buy the latch these connect to separately) - https://reliablehardware.com/products/drawboltblack
Hardware - ACE (I just picked bolts and nuts long and skinny enought to go through the plywood and fans)
Minwax Wood Finish - Early American 230
Polyuerthane Satin Canned Spray
Clear Silicone Caulk

Wiring Instructions:

If you want the fans to just run at 100% without controlling remotely, exclude the USB-C Converter and ESP32 device. Mine ran fine like this constantly powered on for several days, was just a big loud for my liking. I run at 60% now.

Power:
12V PSU (+) → Inline Fuse (2A) → splits to:
├── Fan Red wire (+12V)
└── 12V-to-USB-C converter (+)

12V PSU (-) → splits to:
├── Fan Black wire (GND)
├── 12V-to-USB-C converter (-)
└── XIAO ESP32C6 GND pad

USB-C Converter:
12V-to-USB-C converter output → XIAO ESP32C6 USB-C port

My first 3d printed mockup of a cylindrical filter to see how it goes.
Time will tell to see what the filter picks up over a few weeks.

Im going to print a top grille to help stop cavitation of the air and direct it away and int the room. Also i will fix a small housing on the side to take the speed controller also.

170mm filter
X2 5v 120mm pc fans in parallel to help push through it
Small speed controller.

How do these look after 9 months? We have a ton of dust, these help marginally but are obviously picking lots of fine particles. Just replaced them.

Hi, I'm planning to build my first ap. Could review parts that I picked? Is it good combination? Two ikea filtres + 5 arctic P12 all powered and controlled by 12V 5A. Am I missing something?

Hi guys! Bought 4 Ikea FÖRNUFTIG filters and discovered by mistake that if I arrange them in this configuration, inside it's enough space for 4 x 120mm fans.

To stick the filters together, I've used good old hot glue gun.

It took me some thinking of how to manage the PSU, as I didn't want to put it inside and waste so much space. Also, I wanted a way to easily change the filters, so I've used velcro between the layers.

I know that the PSU is such an overkill, but I haven't found in Europe an easier way to power the fans.

As I want to give it to my mother, I searched for a way to protect her fingers from the fans and the PSU. I found this cheap mosquito net that comes with velcro.

I'm waiting now for some parts to convert it from the PSU to a cheap 12V charger.

So this is the final list for this version:
1 x Mosquito net with velcro
3 x Birch wood shelf - 28cm x 28cm
3m Velcro
4 x Arctic P12 Pro fans
1 x MOLEX to 4 pin fan adapter
4 x FÖRNUFTIG filters
1 x PSU 500W
1 x PC power cable

Let me know if you have any feedback or questions. Working now on an improved v2 with a simpler power supply, fan speed control and Tuya smart functionalities.

 

In this subreddit and elsewhere, the type of noise a PC fan makes comes up more and more. And there's a recurring narrative: Arctic P14 Pro or P14 Max = the villains. Noctua = the heroes.

But the devil — or the sonic paradise — is in the details.

At what speed? At what dBA? In open air or inside a build with a filter? The same fan can sound completely different depending on the context. Two fans measured at the same dBA don't necessarily sound the same — the frequency spectrum, the "color" of the noise, matters too.

At 36 dBA, my subjective pleasantness ratings are:

• Silverstone 184i PRO: 9.5/10
• Arctic P14 Max: 9.2/10
• Noctua NF-A12x25 G2 PWM: 8.7/10
• Noctua iPPC 3000 & Cooler Master SickleFlow 120: 8.5/10
• Arctic P14 Pro PST: 8.2/10

Not exactly the villain/hero story people tell — at least for these fans, at 36 dBA, and in my subjective experience.

And it gets more interesting: inside my DIY HRV AccordFlow with a MERV 13 filter, the Arctic P14 Max produces a deep, calming brown noise — more pleasant than the same fan in open air.

Listen what brown noise sounds like:
https://www.youtube.com/watch?v=_t9uWUyuMUc

Listen what Pink Noise  sounds like— https://www.youtube.com/watch?v=ezwIrxOFFqw

Listen what White Noise sounds like  https://www.youtube.com/watch?v=sSZaNwRU-MA4

 

Sound color is also only part of the equation. CADR matters too.

In my test chamber, at equal dBA, Noctua fans deliver a lower CADR compared to the same device built with Arctic P14 Max fans. That said, don't generalize — I test at quiet levels (35–40 dBA), and the picture can be different at higher levels and on different models of air purifiers. Fan A may be more pleasant at low noise but the opposite at max speed.

This is just the beginning of the conversation — we need MUCH more data, from more people, in more contexts.

 I hope that one day, air purifier and ERV spec sheets will include noise spectrum information — something like a "brown noise" or "pink noise" certification. Do you?

 

N.B. About the Youtube video “The Ultimate 140mm Fan Test”

This video is genuinely useful if you’re shopping for a PC fan to cool your computer and want to know how each fan sounds at 25%, 50%, 75%, and maximum speed. For that purpose, knowing both the dBA level and the sound character at each speed is valuable.

The video lets you hear each fan and judge pleasantness for yourself — which is valuable. The limitation is that except for the first segment (38 dBA for both fans), the other three segments don’t compare at equal dBA levels. So what you’re hearing is fans at different intensities, which makes it difficult to isolate sound color from loudness. To compare sound character fairly, equal dBA is needed first.

https://www.youtube.com/watch?v=LAVfS2ANPDA&t=3s

 

Hi, after learning so much from this community I have decided to make a parametric design with four IKEA STARKVIND filter and four P14 Pro PST fan. In my case, it's PWM controlled by ESP32-C6 via Zigbee set at 27%, which is silent for me, consuming 1W and 17W at max speed.

The tall tower version should be printable on a Bambu Lab A1.

Fully 3d printable with some heat inserts and M3 screw, some seal tape and hot glue.

As it's parametric, feel free to adapt for other filter size, should be generic as long it fit on the 3d printer (half size) and it's square filter.

The STL and BOM with instruction is available at:

https://makerworld.com/en/models/2783729-parametric-crbox-air-purifier-ikea-starkvind#profileId-3094190