November 30, 2025
Silence of the fans
I Made a Quieter Air Purifier
DIY Quiet Purifier sparks “Silence of the Fans” war
TLDR: A DIYer built a quieter air purifier using PC fans; it’s slightly less powerful than a shrouded box-fan model but far quieter, so people may actually leave it on. Comments erupted into a brawl over “caveman tech,” brand worship of Noctua, and whether to DIY or just buy a quiet consumer unit.
A tinkerer swapped the loud box-fan “Corsi-Rosenthal” setup (filters taped to a fan) for a homebrew rig using PC cooling fans, chasing one thing: silence. Tests showed it cleans nearly as well as the classic box on low without a “shroud” (a ring that boosts airflow), though it’s weaker than the shrouded version. But it’s quieter, and that’s the point—people keep quiet machines on longer. Cue the comments going full soap opera. One critic blasted the whole CR trend as “caveman tech with a fancy name,” accusing academia of repackaging what “poor folks have been doing forever.” Brand stans burst in yelling Noctua—the luxe quiet PC fans—like it’s a cult, with one user bragging they swap them into everything from routers to PlayStations. The pragmatists rolled their eyes and said, just buy a quiet consumer purifier like this Conway. Meanwhile, DIY diehards shared wins, noting purpose-built home fans are “3x louder and pricier” than PC fans, linking their own mods (in-wall PC fans). The best comic relief: “Why do computer fans blow air inside?”—which spiraled into a nerdy push-vs-pull airflow bicker. Everyone agrees on one thing: if the teacher turns the loud one off, it’s useless. Noise matters, data or no data.
Key Points
- •A quieter Corsi-Rosenthal box was prototyped using five PC cooling fans mounted in Recticel insulation foam over four MERV 13 filters.
- •The prototype’s power system used a fan hub with SATA power and a mains-to-SATA adapter.
- •Performance testing with a 20 match PM2.5 generation showed the prototype is similar or slightly better than an unshrouded Lasko CR box at low setting, but worse than a shrouded one.
- •Noise measurements at 50 cm using a MacBook Air microphone indicated the prototype is quieter, notably in mid-to-high frequency ranges.
- •The article emphasizes balancing CADR with noise to improve real-world usage of air purifiers.