Apple’s iPhone 7 Lightning headphone adapter packs in a surprising amount of circuitry

By , Oct 6, 2016

iPhone 7 Lightning headphone adapter X-ray iFixit 001

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.

Most notably, it packs in a pretty unique integrated circuit that’s most likely a built-in digital-to-analog (DAC) converter. There’s actually a lot going on in the diminutive adapter aside from the DAC, writes iFixit, including things like an integrated amplifier and an analog-to-digital-converter (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.

Prior iPhones handled both DAC and ADC functions internally via a custom Apple/Cirrus Logic chip on the logic board. The X-ray analysis of Apple’s headphone dongle reveales integrated circuitry marked “338S00140 A0SM1624 TW”.

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.

iPhone 7 Lightning headphone adapter X-ray iFixit 002

Here’s a visual comparison of the CirrusLogic audio chip on the iPhone 7’s logic board next to the exposed DAC/ADC/amplifier chip in the new Lightning headphone adapter.

iPhone 7 Lightning headphone adapter X-ray iFixit 003

The larger iPhone 7 chip “handles more than just DAC/ADC,” explains iFixit, as it also integrates a media codec. It’s not believed to contain an amplifier because there are three dedicated amplifier chips located elsewhere on the iPhone 7 logic board.

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.

Ultimately, it appears Apple’s engineers “did their job” because, as iFixit writes, the tiny adapter seems to perform “better than most people expected or even thought possible”.

Here are the results of a barrage of sound quality tests conducted last month by hi-fi enthusiasts at German computer tech magazine, called c’t.

iPhone 7 Lightning headphone adapter X-ray iFixit 004

Because the iPhone 7 and iPhone 7 Plus lack the 3.5mm headphone jack in favor of Bluetooth headsets or wired Lightning-based ones, Apple’s dongle requires DAC circuitry to convert the ones and zeros from the all-digital Lightning connector to analog signals that audio accessories like 3.5mm headphones need to work.

By the same logic, the adapter also needs ADC circuitry to convert analog signals from a headphone’s embedded microphone into ones and zeros that are fed to the handset via the Lightning port.

However, both new iPhone 7 models still pack in the CirrusLogic chip in order to drive their built-in loudspeakers and microphones, all of which use analog signals.

Later this month, Apple will release its new wireless earphones, called AirPods.

The earphones integrate a custom-designed Apple W1 chip that extends battery life over standard Bluetooth connections while supporting advanced features like zero-configuration automatic pairing, seamless switching between devices without re-pairing and more.

Source: iFixit, Creative Electron

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  • Ninja Ass

    Im the only one here think Apple did great moves by removing headphone jack .. ppl who hate iPhone because they remove then see you guys in 2018

    • Blacklight: Retribution

      Same. It isn’t dealing-breaking for me.

      • Shadowelite123

        Exactly! I don’t get why people say it’s a deal breaker. I guess they just hate change so much, yet they want us to have the newest technology and to improve. There can’t really be improvement without change.

    • techfreak23

      So far it hasn’t been a huge issue for me. I have run into the situation multiple times though where I want to charge while using my headphones. Usually at night when I’m listening to music in bed.

      • You can sleep in you bed with headphones in interesting.. I’d wake up tangled in wires if I tried that lol. The issue with me was using a portable charger then wanting to FaceTime while using headphones because other people were around.. Funny thing is, I don’t care enough to buy those cheap adapters the allow the phone to both at the same time

      • techfreak23

        Yeah I’m with you on the splitter. Not worth it to me. And sometimes I like to lay in bed with my headphones, like I am now actually, but I usually don’t fall asleep with them. I’m planning on getting the AirPods later this month!

      • Hopefully they have a ping function and they can play a loud enough sound like the “find my phone” tone.

    • jo3y

      Not a deal breaker by any means, but there are sometimes i wish i can charge my phone and listen to my music with earphones (again that doesnt come up much either)

    • Jack Wong

      Been using BT earbuds for years, the one from Anker is less than $30 and give almost 5hours play time in my case.

    • n0ahcruz3

      Totally not a deal breaker for me lol am i the only one here that thinks the camera bump on the 7/7+ compliments the overall look of the phone? No seriously lol however the 6 and 6s my gosh the camera bump looks totally horrendous..

      • techfreak23

        Definitely looks a little better than the 6/s. More tolerable.

    • The ones complaining about Apple pushing audio to become wireless are most likely also using technologies like Wi-Fi, IR TV remotes, and Bluetooth game controllers, yet none have complained about those.

      Imagine having to use a tethered remote control on your TV.

    • Zach Champion

      Sure it may not be a huge inconvenience for everybody, but what does it add?

      • Storm

        More room inside the iPhone 7 for other stuff?

    • dedegarrido

      I think they should also remove the lightining port… but sure, they wont. (And add super fast wireless charging, and water proofing to the iphone, just like the apple watch). It would make things simpler…

      • Ninja Ass

        They have great chance to remove lightening port by replacing like Apple Watch ..size of port will be same as lightning port but it will not have a pin just a glass with light transfer and in iPhone also there will a glass so there will Be no hole.. now cable n iPhone connect with magnet n send data n charge with light like optic fiber … so there will no chance of getting water in iPhone and it will be fast charge n data transfer … sorry English hope you understand what I m trying to say this my idea .. maybe I m wrong

    • smtp25

      Problem for me is, I lose, break, leave at home my headphones all the time. So being able to buy cheap replacements from anywhere is great. Now I can’t its either the $50 Apple headphones or having a ton of adapters spare. I’m postive the aftermarket will catch up and have lightning enabled headphones for relatively cheap

      • Storm

        Have you tried not losing, breaking or leaving your headphones behind? Could work out cheaper…

    • ravinigga

      Already moved to Bluetooth headphones and I got 6s plus.
      Much better then annoying cables, but I bought beoplay h8 for 430€ is expensive but worth any penny also plus side I can remove the battery and earpieces if I wanna replaces it.