Apple’s Lightning to 3.5mm Headphone Jack Adapter Gets the Teardown Treatment

Repair wizards over at iFixit along with their pals at Creative Electron gave Apple’s new $9 iPhone 7 Lightning headphone adapter a thorough X-ray treatment. The analysis has revealed a surprising amount of circuitry inside of the dongle.

An iFixit contributor by the name of oledturkey03 sliced open his adapter, showing off the IC under the plastic, which showcased a part number 338S00140 A0SM1624 TW, which didn’t actually provide many details. However, it’s a reasonable expectation that the IC contains a digital-to-analog convertor (DAC) and an amplifier, along with an analog-to-digital convertor (ADC).

“We’re surprised how much electronics Apple was able to include inside this little cable,” said Creative Electron, which builds X-ray inspection systems for electronics.

iFixit and Creative Electron think it’s most likely some sort of a DAC chip.

The dongle connects legacy 3.55mm headphones to the iPhone 7, with one end providing a standard female 3.5mm port while the other is a male Lightning connector.

The size of the IC within the adapter has led many to speculate that Apple cut some corners to get the job done, and the publication has put a side-by-side with the audio chip in the iPhone 7 (on the logic board), right next to the exposed chip in the new adapter:
As for audio quality:
The takeaway seems to be that in some areas, the sound quality does measure a bit worse from the adapter than we might be accustomed to. For instance, when playing an uncompressed 16-bit audio file on the iPhone 6s, the dynamic range dropped from 99.1 dB at the headphone jack to 97.3 dB at the adapter.
Though keep in mind, this slightly lower measurement is still higher than the theoretical maximum you get from a compact disc (which is 96 dB). So, is it a difference you are likely to notice? If you sit in a quiet room with a really, really good pair of headphones … and you’re a canine, the answer is: maybe.
The findings did show that there are some drop offs in quality, like playing an uncompressed 16-bit audio file. However, the differences they did notice are probably not any that the vast majority of listeners would be able to pinpoint. If a user is plugged in with top-of-the-line headphones then, maybe, they can tell, but with standard headphones the difference appears to be minimal.


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