X-ray of Apple's iPhone 7 Lightning headphone adapter finds mystery circuit, likely for DAC

AppleInsider

Apple's new Lightning to 3.5-millimeter headphone adapter -- bundled with every new iPhone 7 and iPhone 7 Plus, and also sold separately for $9 -- features a unique integrated circuit, the purpose of which cannot be verified, but has likely been deduced.

Via iFixit and Creative Electron.

Partnering with Creative Electron, the repair experts at iFixit took an X-ray view of Apple's new cable, finding a surprising amount of circuitry inside of Apple's diminutive adapter. In particular, the Lightning connector is accompanied by a "mystery" integrated circuit identified only by an Apple part number: "338S00140 A0SM1624 TW."



While the exact purpose of the IC remains unknown, iFixit surmises that it's likely a digital-to-analog converter accompanied by an an amplifier and an analog-to-digital converter. Those are necessary to convert digital audio from the Lightning jack to analog sound that can be heard by human ears --?and also to convert input sources, such as sound through the EarPods microphone, into digital audio that the iPhone can use.



In previous iPhone models, the DAC and ADC were found inside of the handset, converted via the integrated 3.5-millimeter headphone jack. But starting with this year's iPhone 7 series, Apple has officially ditched the headphone jack in favor of Lightning- and Bluetooth-connected audio, though the company has bundled its new Lightning to headphone adapter with every new iPhone 7 sold.

Via iFixit and Creative Electron.

Notably, the iPhone 7 and iPhone 7 Plus still include a separate DAC and ADC circuit inside, because it is necessary to convert audio for the device's own onboard stereo speakers and microphone inputs.



Apple views its own adapter as largely a stopgap on the path to an entirely wireless future. In that direction, the company also introduced its own W1 wireless audio chip, which aims to simplify the process of pairing Bluetooth accessories.



The W1 chip is one of the defining features of Apple's upcoming AirPods wireless earbuds, as well as a trio of upcoming Beats-branded headphones. A real-world test with the new W1-equipped Beats Solo 3 found that Apple's proprietary technology has improved battery life and range, in addition to making it easier to pair and use with multiple devices.

zroger73

It's not "likely" a DAC. It is most definitely a DAC. The Lightning connector only outputs a digital signal. Speakers are analog devices. You gotta make the conversion somewhere in between! Duh.

thrang

It's a DAC. I find the sound quality on the 7 Plus improved. Perhaps a better DAC, and likely moving the DA conversion outside eliminates interference from the electrical circuitry of the phone itself...

Soli

zroger73 said:

It's not "likely" a DAC. It is most definitely a DAC. The Lightning connector only outputs a digital signal. Speakers are analog devices. You gotta make the conversion somewhere in between! Duh.

Don't confuse Apple lack of application with an inability to exist. We know it's a DAC and AMP because we've seen it verified from a physical teardown of the adapter 2 weeks ago, but don't think that you need to have a dedicated analog connector in order to have analog I/O from a sophisticated, versatile connector like Lightning. Apple's 30-pin iPod connect and DVI-I is an unsophisticated example of a connector that contains both digital and analog pins. Modernized, that same connector could use less pins and switch them around as needed, if that had been the most advantageous route.

Soli

1) I'm enjoying the 3" adapter on my headphones as it's easier to find the thicker and heavier end to plug into my iPhone 7 series without looking, and they don't see to get tangled as easily.

2) In terms of audio, most impressive is the speaker phone on the new iPhone is louder than my BT speaker for my bathroom. Granted, it was a cheap $20 stereo BT speaker system from Amazon, but it's considerably larger with considerably larger speakers so I wouldn't have expected it to be bested by a phone. In any regard, making a call with the speakerphone in an any with loud machinery—which I unfortunately have to do often—is finally hearable.

zer0her0

What I'd be interested to know if the DAC is the same part in the bundled earbuds as it is here in this adapter. I'd assume so, but still be interested to see/know of sure.

wiggin

AppleInsider said:

While the exact purpose of the IC remains unknown, iFixit surmises that it's likely a digital-to-analog converter accompanied by an an amplifier and an analog-to-digital converter. Those are necessary to convert digital audio from the Lightning jack to analog sound that can be heard by human ears --?and also to convert input sources, such as sound through the EarPods microphone, into digital audio that the iPhone can use.

Interestingly regarding an analog-to-digital converter, per this article Apple's adapter does not support the mic and controls on 3rd party headsets, rending them useless for phone calls, volume adjustments, etc. I think a lot of people are going to get their new iPhone 7s and be surprised their existing headsets don't work even with the adapter as this limitation is not spelled out in Apple's description of the adapter. Is the method 3rd party headsets use so different from what Apple's own headsets use that it couldn't have support both?

http://www.macworld.com/article/3127211/iphone-ipad/7-solutions-for-the-iphone-7s-lack-of-headphone-jack.html

If this is true, bad form on Apple's part to not be more clear about the limitation.

rob55

Interestingly regarding an analog-to-digital converter, per this article Apple's adapter does not support the mic and controls on 3rd party headsets, rending them useless for phone calls, volume adjustments, etc. I think a lot of people are going to get their new iPhone 7s and be surprised their existing headsets don't work even with the adapter as this limitation is not spelled out in Apple's description of the adapter. Is the method 3rd party headsets use so different from what Apple's own headsets use that it couldn't have support both?

http://www.macworld.com/article/3127211/iphone-ipad/7-solutions-for-the-iphone-7s-lack-of-headphone-jack.html

If this is true, bad form on Apple's part to not be more clear about the limitation.

There seems to be conflicting information in the Q&A section for the adaptor on Apple.com. Some say it works, others say it sort-of works, yet others say it doesn't.

http://www.apple.com/shop/question/answers/product/MMX62AM/A/is-this-a-trrs-adapter/QDUXYH22KCDPCAF29

chrisrosa

You guys literally already did a teardown and found a DAC. http://appleinsider.com/articles/16/09/20/teardown-finds-dac-chips-in-apples-lightning-earpods-lightning-to-35mm-adapter-for-iphone-7

spacekid

chrisrosa said:

You guys literally already did a teardown and found a DAC. http://appleinsider.com/articles/16/09/20/teardown-finds-dac-chips-in-apples-lightning-earpods-lightning-to-35mm-adapter-for-iphone-7

They don't read their own web site.

jonyo

wiggin said:

AppleInsider said:

While the exact purpose of the IC remains unknown, iFixit surmises that it's likely a digital-to-analog converter accompanied by an an amplifier and an analog-to-digital converter. Those are necessary to convert digital audio from the Lightning jack to analog sound that can be heard by human ears --?and also to convert input sources, such as sound through the EarPods microphone, into digital audio that the iPhone can use.

Interestingly regarding an analog-to-digital converter, per this article Apple's adapter does not support the mic and controls on 3rd party headsets, rending them useless for phone calls, volume adjustments, etc. I think a lot of people are going to get their new iPhone 7s and be surprised their existing headsets don't work even with the adapter as this limitation is not spelled out in Apple's description of the adapter. Is the method 3rd party headsets use so different from what Apple's own headsets use that it couldn't have support both?

http://www.macworld.com/article/3127211/iphone-ipad/7-solutions-for-the-iphone-7s-lack-of-headphone-jack.html

If this is true, bad form on Apple's part to not be more clear about the limitation.

I've used the Apple supplied lightning-3.5mm adapter with my Bose QC15 headphones and iPhone 7, and everything works fine with the Bose inline controls and mic, buttons for track back/forward, play/pause, calling up Siri, volume up/down, etc, it all works for me.

bobolicious

Has anyone found any audio quality reviews or tests ?

- iPhone 7 w/OEM adapter/DAC
- prior iPhone analogue
- prior iPhone w/OEM adapter/DAC
- prior iPhone non OEM DAC

Apple has notoriously well reviewed audio performance in the past,
including the Airport Express DAC & as I recall a Wolfson DAC in the iPod 4G...

I understand unless using 24/48 or 24/96 there is little or no discernible difference (see Audio MIDI Setup/Output)
and requires using a 3rd party FLAC player for such as http://bowersandwilkins.custhelp.com/app/answers/detail/a_id/204

dps098

What about all the analog based credit card swiping adapters out there (yes, many vendors still use them)?

mac_128

dps098 said:

What about all the analog based credit card swiping adapters out there (yes, many vendors still use them)?

Square has already said their card reader will be compatible. Which makes sense as this adapter doesn't necessarily do anything differently than a native iPhone headphone jack.

wiggin said:

AppleInsider said:

While the exact purpose of the IC remains unknown, iFixit surmises that it's likely a digital-to-analog converter accompanied by an an amplifier and an analog-to-digital converter. Those are necessary to convert digital audio from the Lightning jack to analog sound that can be heard by human ears --?and also to convert input sources, such as sound through the EarPods microphone, into digital audio that the iPhone can use.

Interestingly regarding an analog-to-digital converter, per this article Apple's adapter does not support the mic and controls on 3rd party headsets, rending them useless for phone calls, volume adjustments, etc. I think a lot of people are going to get their new iPhone 7s and be surprised their existing headsets don't work even with the adapter as this limitation is not spelled out in Apple's description of the adapter. Is the method 3rd party headsets use so different from what Apple's own headsets use that it couldn't have support both?

http://www.macworld.com/article/3127211/iphone-ipad/7-solutions-for-the-iphone-7s-lack-of-headphone-jack.html

If this is true, bad form on Apple's part to not be more clear about the limitation.

I'd be interested to know if all of those third party headsets were originally compatible with the iPhone to begin with. Different manufacturers can use a different TRRS configuration, swapping the mic and ground orientation. Essentially these controls are all achieved by shorting the ground, but I suppose it's possible they used some different non-standard implementation, or maybe a higher power consumption for analogue functions than the Lightning adapter outputs.

thrang said:

It's a DAC. I find the sound quality on the 7 Plus improved. Perhaps a better DAC, and likely moving the DA conversion outside eliminates interference from the electrical circuitry of the phone itself...

It's hard to believe anyone expected Apple to implement an analogue output from Lightning, despite the capability of Lightning to dynamically route signals, especially after 4 years of Apple putting DACs in all of their Lightning adapters and docks, when analogue would have been much cheaper and easier, not to mention no hint of it in the Lightning audio specs published almost 2 years ago.

zer0her0 said:

What I'd be interested to know if the DAC is the same part in the bundled earbuds as it is here in this adapter. I'd assume so, but still be interested to see/know of sure.

My guess is maybe not. There are two different part numbers. The difference appears to be in the wiring. Both have 7 discrete wires from the Lightning interface, but the adapter only have 3 discrete connections, with the other 4 sharing a common ground. The EarPods on the other hand, appear to have 7 discrete wires from end to end. So it could be a different amp configuration in the chipset, maybe for balanced signals?

larryjw

dps098 said:

What about all the analog based credit card swiping adapters out there (yes, many vendors still use them)?

I have the paypal credit card swiping device. Connected to adapter, the paypal device works fine. I don't use any other such device, so I can't vouch for other such devices.

tardis

I have an Apple Lightning headphone adaptor with my B&W P5 headphones connected to my iPhone 6S. The audio controls and microphone all work.

My first listening impressions suggest that there is a difference in sound quality between plugging the headphones into the iPhone's headphone jack and plugging the same headphones into the Lightning adaptor’s headphone jack, and that the Lightning adaptor's audio sounds “better".

Not a huge difference, but it sounds like while listening via the iPhone's headphone output the effect of compression is more noticeable than via the iPhone's Lightning output.

I'd be interested to see other reviews, especially a controlled "double blind" audiophile's test, but it looks like Apple's $10 adaptor can give the same improvement in audio quality as those $100 or more DAC headphone boxes

techaccident

wiggin said:

AppleInsider said:

While the exact purpose of the IC remains unknown, iFixit surmises that it's likely a digital-to-analog converter accompanied by an an amplifier and an analog-to-digital converter. Those are necessary to convert digital audio from the Lightning jack to analog sound that can be heard by human ears --?and also to convert input sources, such as sound through the EarPods microphone, into digital audio that the iPhone can use.

Interestingly regarding an analog-to-digital converter, per this article Apple's adapter does not support the mic and controls on 3rd party headsets, rending them useless for phone calls, volume adjustments, etc. I think a lot of people are going to get their new iPhone 7s and be surprised their existing headsets don't work even with the adapter as this limitation is not spelled out in Apple's description of the adapter. Is the method 3rd party headsets use so different from what Apple's own headsets use that it couldn't have support both?

http://www.macworld.com/article/3127211/iphone-ipad/7-solutions-for-the-iphone-7s-lack-of-headphone-jack.html

If this is true, bad form on Apple's part to not be more clear about the limitation.

I'll echo what jonyo said. I've used the adapter with several headphones from Apple and others, and the inline controls and microphones all work 100%. Apple did a fine job.