The Thermodynamics Behind the Mac Pro

Alexander George, writing for Popular Mechanics:

Ligtenberg’s group built the Pro’s fan system — three axial fans in the front, with a blower in the back. Since most off-the-shelf fans would be too loud, Apple designs them internally.

“Years ago, we started redistributing the blades ,” he says. “They’re still dynamically balanced, but they’re actually randomized in terms of their BPF [blade pass frequency]. So you don’t get huge harmonics that tend to be super annoying.”

Noise is a major factor in the design of modern machinery. In this case: “That [solution is] borrowed almost entirely from automobile tires,” Ligtenberg says. “There’s a bit of math behind it, but you can create broadband noise instead of total noise with that technique.”

Obsessing over the fan noise — reducing it where possible, and making what noise there is as pleasing to the ears as possible — is Apple at its best.

★ Tuesday, 17 December 2019