Apple's Lightning Headphone Adapter: Analog or Digital?

Anybody in a betting mood?

Back in June 2014 I reported on a little confusion that never seemed to be cleared up. The question is, "Can the Lightning port transport analog audio?" Most sources say no. But is that true?

Now that the new iPhone7 headphone adapter is out in the wild, tear-downs are starting...I'm sure we'll be seeing more soon. The first one pointed to in a 9TO5MAC article claims this Vietnamese adapter teardown shows the adapter has a DAC chip. Okay so far.

Then this German article (translated link) claims the adapter isn't as good as the headphone jack on the iPhone6 pointing to a loss of dynamic range. This Redit poster thinks it's all a bit silly. However, the article includes this (Google translated) tid-bit.

In the measurements, it was irrelevant whether the adapter to the iPhone 7, 7 Plus or iPhone 6S was attached: The results agree to the decimal. Strikingly, however, was that the adapter on iPad delivers significantly better result list than the iPhone. This may indicate that in the adapter no separate D / A converter is seated, but the audio signal is already transmitted in analog form via the Lightning jack. Since the Lightning chips with their remote site in iPhone / iPad can each negotiate in the cable, which is transmitted, that would be quite possible. As long as Apple is silent on the subject, can only bring further tests certainty here.

The article published this table of measurements (here translated):

160921_Blog_iPhoneAdaptorDACorNot_Chart_Measurements

What's interesting to me here is that the maximum output of the adapter changes when going from the iPhone7 to the iPad Air. If it is digital, shouldn't full scale be that same on both. Also note, when going from the iPhone6 jack to the adapter, and the iPad Air jack to the Adapter, the gain change remains the same at just under unity. Calculations were 0.88dB and 0.9dB...the difference can easily be chalked up to rounding errors in the published data.

Also, the output impedance changes slightly from 0.37 Ohms on the iPhones to 0.56 Ohms on the iPad, which it shouldn't do if it's all digital. If there is an analog out from the iOS device and a power amp in the adapter, there may be an analog feedback path, or possibly a slightly different output protection scheme on the two devices—with an output impedance that low it's likely to need some protection circuits or sensing in the case of short circuiting when the plug is inserted or removed.

In a comment to iFixit's iPhone7 teardown we find this exchange:

160921_Blog_iPhoneAdaptorDACorNot_Chart_Comments

Well, there you have it, plenty of evidence for and against. My take is I'm glad it's got that low an output impedance, should be much better for people with mudlti-balanced armature IEMs.

DAC or Analog, what do you think?

COMMENTS
OldRoadToad's picture

My ears are "analog". I hear music, not 0s and 1s. There is nothing wrong with "digital" music as none of us listen to "digital" music. We listen to music. The format is irrelevant as regardless of how it was recorded we listen with our ears.

The anal retentive among us might claim to hear a difference but I doubt it. The Beach Boys never sang, "I can hear digits"...

Apple can be so weird.

ORT

jagwap's picture

The difference in output between iPhone and iPad could be down to European volume capping of the iPhone, which will also apply when the adapter is used.

The higher output impedance on the ipad could suggest a current loading issue on the amp at the higher output. If the output impedance is re-measured at -7dBV on the ipad it may show up the same as the iPhone.

So maybe still not proven to be digital.

jagwap's picture

Although that Vietnamese teardown show a part that looks very much like a Cirrus Logic part number, so my money is on Yes, a DAC.

Arve's picture

Are you referring to 338S* or something else? In that case, there are components in the iPhone from Dialog Semiconductor with the same prefix, and they _just_ released a few ultra-low power CODECs, of which the DA7217 and DA7218 seems to match the size of the chip as shown in the Vietnamese teardown.

ultrabike's picture

If this is a DAC/Amp indeed, I feel there could be positive repercussions in portable audio.

Awesome! :)

drblank's picture

very often with my iPhone. I prefer to listen to music on my home stereo which is based on Lossless and Uncompressed files.

The only thing that would be of interest to me is getting someone at Apple to come forward and explain exactly what's going on just to clear up any misconceptions. I hear a lot of Anti-Apple people make up fictitious lies about Apple because they are coming from a place of hatred, which is not productive at all.

If the "dongle" has an internal DAC, then it has an internal DAC. If it's passing 2 channel analog from the internal DAC, which is does have, then it's passing a 2 channel analog signal.

The point is this. If you want to continue using existing 2 channel earbuds or headphones, then you have to use the dongle. If you want to buy a new part of Lightning based ear buds/headphones, there are plenty to choose from that are starting to emerge on the market. Some have built-in DACs like the Audeze EL8 Titaniums that have a Lightning connector, and others will be coming out on the market.

What I find hilarious is that there are other companies like Motorola, and potentially HTC, that are also ditching the 3.5mm jack, but they are using the USB-C connector. So, they will have to deal with the exact same issue only surrounding the USB-C connector.

Now, why isn't Apple using the USB-C connector on the iPhone? I can conjure up several "POSSIBILITIES" and any combination of them can be the reasons why.

1. Apple has already made a HUGE investment in the design of Lightning connector and the related accessories.
2. 3rd Party companies have also made a HUGE investment in the design of their Lightning connector based products.
3. Existing consumers have also made their investment in Lightning connector based accessories.
4. USB-C, from my understanding, is STILL going through some small changes and isn't 100% solidified. At least that's what I read in a recent article. Intel has been a BIG proponent of killing off 3.5mm jacks in favor of USB-C, so it's going to happen at some point on all devices if Intel gets their way. I personally think that Apple made the decision to ditch 3.5mm partly because of room inside is limited and why they didn't go with USB-C is something that I think Apple should come forward and clear up anyone's minds.
5. As a result of customers using cheaply made Lightning cables/chargers, that caused damage to the product, they formulated the MFI campaign so help ensure that 3rd party mfg were properly designing products that won't harm these devices, and the licensing fees Apple charges pays for R&D of the Lightning technology, along with administrative costs, marketing costs, etc. Apple's not trying to make a killing from licensing, it's not enough to even worry about. Having the MFI campaign helps everyone so that people simply buy quality products, 3rd party companies also become preferred over the cheap knockoff products that plague the market that may actually cause damage. Unfortunately, all of that costs money.

Either way you look at it, 3.5mm jacks are going away, even on Android devices. This Is just the beginning. And everyone that gets upset about having to buy a new set of headphones, etc. Think of this. In the AVERAGE person's lifespan, how many people that buy headphones have the same original pair since their first pair? I would venture to guess that 99.99999% of the headphone wearing population have gone through more than 1 pair of headphones in their lifespan. I know I've gone through at least 6 or 7 headphones, and at least 3 or 4 pairs of earbuds and I don't really use them all that much.
My point is, whether you want to hear it or not, if you learn to adapt to change, it will lower your stress levels, if you resist it, it just adds to the stress. Smartphones by any of these mfg, whether it's Apple, LG, Samsung, etc. etc. aren't high end audio devices. NONE OF THEM are going to stick a high end DAC circuit inside similar to what a company like Astell & Kern is going to use in their multi-thousand dollar mobile music players. Please get over yourselves. It's all going to blow over in a few weeks once people simply get past the change.

The fact is that for the AVERAGE consumer, which is what all of these smartphone companies are looking at, have to consider the market trends. Apple, like Moto, like others are noticing that wireless earbuds/headphone sales are starting to eclipse wired. So, right now, everyone is in this state of change and some people adapt and figure out how they are going to move forward and some go kicking and screaming. But I find it completely ridiculous to switch a different platform for a computing device over a silly 3.5mm headphone jack. To me, coming from an IT background, switching platforms over a simple connector is the DUMBEST reason to switch. Just sayin...

I will crack up when more and more Android mfg start removing 3.5mm jacks. It's going to happen, and it's already starting. Moto did it, and I don't hear a lot of complaints. Not that they sell a lot of units in the first place. Maybe that's the reason.

Either way, just learn to adapt and accept it, it really isn't that big of a deal.

Arve's picture

An FYI here: Audio in USB-C/3.1 isn't yet a done deal. It's not decided if and how analog passthrough is to be done, and the features of the spec itself are not done either.

And Intel are apparently planning to ruin USB audio for us all - they have some spec proposals, which you can read more about here: http://www.anandtech.com/show/10273/intel-proposes-to-use-usb-typec-cabl...

In that link, you'll find some slides. On the fifth slide, you'll find this word:

HDCP

In other words, Intel want to add DRM to USB audio. In my view, that's going to completely ruin USB for audio forever.

skris88's picture

Agreed!

Initially I was upset about Apple changing the connector for audio. There is a "perfectly" good 2.5mm connector too (or does Nokia - now Microsofot - hold that 'patent'?). But now I'm resigned.

Things change. The majority of users simply use the standard buds that come with a phone, and the rest go Bluetooth because they want to go wireless. Us audiophiles are simply too small a bunch to be worth considering.

Look it at this way, a digital output will allow better external DACs to be used. Come home, plug in your smartphone onto it's docking bay where it charges and connects to an external DAC that your Hi-Fi system can use.

jirams's picture

So the increased cost (£10 in UK) of the iPhone doc is no doubt due to the cost of the embedded DAC to support the 3.5mm analog socket on rear?

miglto's picture

The lightning-30pin adapter includes a Wolfson DAC chip. So no I don't think there's anything much new there.

halcyon's picture

Why do we care? You still have to pay Apple $4 lightning chip tax for the fact that they encrypted USB.

Yes, you can gamble with non-licensed adapters/headphones, just like you could with non-licensed charging cables. Good luck with that.

Steve Jobs said that the goal is a "totally closed ecosystem, where Apple controls everything".

It's a money grab.

Nothing to do with Audio quality (you could already use external lightning DACs), what users want (get rid of their $X000 IEMs, LOL?), versatility (listen+charge at the same time) or compatibility (just plug any headset and go).

It's just Apple's way of saying "We overpaid $3 bn for Beats, now it's time for you to pay".

I hope it dies a horrible death and becomes known as the "Osbone move of Apple."

miglto's picture

The slightly lower dynamic range is a non-issue whereas the much lower output impedance and higher voltage are key - the adapter sounds markedly better.

miglto's picture

The adapter works will iPhone 5 and newer (requires iOS10) - none of these devices included an analog connection on the lightning port. The lightning-30pin adapter included a DAC (a pretty decent Wolfson at that) - it would have made no sense to include this at the time if the lightning connector supported analog in/out.

Headphone4life's picture

I don't see why people are so upset about them getting rid of the 3.5mm jack. For a phone using wireless headphones is perfectly fine for most people. I mean who's using there iPhone for critical listening anyways, most people like us have stereos and hifi dap's for that. I've never been into wireless hp's and even though I don't us an iPhone I'm going to buy my first wireless hp soon, because that's the way its going and I for one am ok with that.

elfary's picture

Tyll,

The dongle adjust the outputs depending on if the idevice is capped or it is not.

My european dongle belts out 1v when attached to my Japanese iPhones but only belts out 0.5 volts when is attached to an European iPhone.

Note: EU caps the volume of idevices that are sold with bundled earphones. iPad are not capped cause no earphones no way to apply the CENELEC regulations.

elfary's picture

Yuriv measured throughly a dongle plugged to a US iPhone -> Output it's 1 volt.

jseaber's picture

Output voltage of the iPhone 7 Lightning to Headphone adapter (model A1749) measures 1.0VRMS @ 32 ohms via iPhone 5S and iPad under several apps.

One signal generator app I tried only produced 0.4VRMS output.

Output Voltage: 1VRMS
THD+N @ 1kHz: < 0.003%
Noise (A Weighted): -104 dBu
Power into 32 ohms: 31 mW
Output Impedance: 0.3 ohms

Measurements were conducted via dScope Series III analyzer and Fluke 287 RMS Multimeter using AfG Audio Function Generator and 1kHz FLAC files @ 48kHz sampling rate for test tone generation.

thefitz's picture

If it's a straight-up analog signal, any third party could be able to make "lightning" replacement cables for your phone the same way they make 1/8"/1/4"/XLR jack replacement cables for any existing headphone. That's a pretty big distinction.

JMB's picture

The Sine or upcoming iSine headphones come with an additional lightning (cipher) cable for iPhones/pads which also have an in line chip (=DAC). Audeze claims 24 bit resolution but otherwise i did not find much more specs about that DAC. I expect that a lot more headphone makers will follow. There are recently a lot of portable DACs/headphone amps available but cables with a miniaturized DACs inline will be a new trend

casperbxl's picture

Has a nice solution with the Lightning connector, with a DAC/AMP that is a bit more DAC/AMP than the Apple solution. FIIO i1 (192/24 + AMP); fully in metal + lightning connector + 3.5mm + volume buttons;
or the FIIO BTC-MMXC via Bluetooth to MMXC connectors, wireless.

TempuraSwindler's picture

So far what the specs and measurements really prove is that you shouldn't waste your valuable real estate on your phone on anything more than 44.1/16. The lower frequency for 96 vs 44.1 is telling. I don't really care about the reduced DR, that tiny difference is going to be imperceptible through my tinnitus (though isn't one of the points of getting the DAC and amp out of the source to LOWER the noise floor?) But this device will literally be able to make better use of 44.1 information than 96.

Arve's picture

"If it is digital, shouldn't full scale be that same on both."

How much power a device can draw on iOS devices is software controlled, and it's entirely possible that iOS 10 allows an iPad to draw more.

Lawk's picture

According to the teardown there is still a DAC (CirrusLogic) inside the iPhone 7. I would have assumed the adapter itself is analog and does not contain an additional DAC. Or maybe it is, and the DAC inside the phone is use for the speaker. I don't know.

I don't think apples target audience really struggles with this, but for us audiophiles I would suggest just going with a phone that has a good DAC and a the good ol, 3.5mm Jack.

HTC 10
LG V20, V10
ZTE Axon 7

if you need volume.

If you don't and just run 32ohm cans and or other efficient IEM's. I think my Samsung Galaxy S7 Edge sounds pretty good.

There are other Exynos phones that sound good, and there are good Qualcomm stock implementations.

Arve's picture

Short of an _actual_ digital speaker (which, in theory can be built, in practice not), the speakers inside the iPhone needs a DAC, and that's what the internal DAC/ADC is used for.

tinyman392's picture

I'm going to go out on a lim and make a thought experiment. Let's say that we have a DAC+amp combo who can take up to, but no more than 1W of power from the power source (USB, Lightning, Power, etc.), but requires a minimum of 0.25W to run. Let's further say that we have two power sources, one that runs at 0.5W and one that runs at 1W. Will this DAC/amp have the same sound characteristics from the two sources? My money is on no, but I could very well be wrong.

Bring this to the iPhone and iPad comparisons. The iPad is definitely capable of being able to safely output more power than the iPhone. If it can do this, then we run back to my thought experiment. If differences are expected with different amounts of power, then we will have expected differences and the differences are independent of digital or analog.

I personally put my money on the chip is a DAC for two reasons. The first being that the serial number is damn near identical to that of a known DAC. The second being that Apple's own spec specifies that the Lightning connector is digital only; that was the whole point of the Lightning connector, to be a digital connector getting rid of analog.

brause's picture

I use the Audioquest Dragonfly preamp/dac connected to my iphone via the lightning camera adapter. I connect the Dragonfly with my old iPad (iOS9 only) with a 30 pin to usb adapter. Both work.

This means: if the lightning camera adapter has a dac, then the 40 pin adapter must have a dac, too. And if both have a dac, why would you daisy chain another dac (=the dragonfly).

And if I plug the dragonfly into my Macbook via USB without any adapter, it also works.

It is concluded that the lightning connector has no dac.

skris88's picture

A DAC can also be a pass-through device. I have one with USB in and analogue headphone out but also SPDIF out.

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