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AirPods Evolution

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AirPods Evolution

Dec 2021

Apple was not the first company to develop wireless earbuds, but they’ve defined the category since introducing AirPods in 2016. The product has evolved dramatically, adding more sensors and new features packed into an ever-shrinking form factor.

What makes an AirPod an AirPod? How do they fit so much functionality in such a small volume?

When we peel the skin back, we find that Apple completely redesigned AirPods with each major generation. Let’s explore with the help of some crispy CT scans.

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Intro image for the scan.

AirPods 1st Generation

December 13, 2016

The first-generation AirPods marked a new category for Apple. Scheduled for release in October 2016, delays pushed them to December. By looking inside, we can understand why manufacturing them was such a challenge.

Packed into the area behind the speaker is a cluster of rigid-flex electronics. The construction would make an origamist blush. Holding the folds without creasing the flexible substrate during assembly is vital and tricky.

A microphone in the stem base is rotated slightly toward the wearer’s mouth, measuring just 2.1mm x 1.2mm. It hides behind the pair of contacts used to charge the battery.

Infrared sensors on the surface of the enclosure just behind the earpiece enable one of AirPods’ key magic features: remove the earbud to pause your music, and replace it to play.

Intro image for the scan.

AirPods Pro

October 30, 2019

Three years later, Apple released AirPods Pro, which packed active noise canceling and several other new features into an even smaller form factor. In 2020, Apple sold 110,000,000 AirPod products. Talk about mass manufacturing.

To deliver these upgrades, Apple completely redesigned the internals of the earbuds. The battery has moved from the stem to the head; the electronics cluster also stayed in the head. A very dense PCB simplifies the assembly by concentrating the electronics into a single component.

The Pro ditched the down-facing microphone in favor of two stem-based microphones. The microphones are substantially larger than the first-gen mics (3.4x2.4mm), but we wonder if voice pickup would have been better with the microphones pointed out of the bottom of the stems.

AirPods Pro introduced a new user interface affordance: squeezing the stem can pause music, change noise cancellation settings, or summon Siri. Force sensors are visible in the stem along with an antenna.

In addition to active noise canceling, AirPods Pro introduced Adaptive EQ and the ability to execute a fit check via the paired phone. A microphone hides directly in front of the speaker to hear what you hear.

Intro image for the scan.

AirPods 3rd Generation

October 26, 2021

Two years after AirPods Pro comes the third generation of AirPods. These are not marketed as “pro,” but they sure look the part. Cue the fights over which is better.

The electronics and batteries fully switched positions from the first-generation AirPods, electronics to the stems, and batteries to the head. A single PCBA contains most components leaving a few distributed sensors.

The downward-facing microphone has made its return, situated between the charging contacts at the bottom of the stem. At 2.9x1.8mm, these microphones are a size between the Pro and G1. Despite the smaller size, could the downward-facing mic deliver better audio quality?

Behind the earpiece is a set of skin-contact sensors, and below them is the third microphone. AirPods G3 don’t have active noise cancellation, just adaptive EQ. Is the location of this mic just a packaging choice, or did the location on the Pros impact performance?

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