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Topic: Apple Lightning and digital/analog output (Read 17646 times) previous topic - next topic
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Apple Lightning and digital/analog output

May I ask a question about the Lightning functionality?

I have finally upgraded to an iPhone with a Lightning connector and am interested in playing the music on my iPhone in my car.  Prior to getting this phone, I had been using a cable that adapts the 30 pin connector to RCA plugs.

I purchased an Apple brand Lightning to 30 pin adapter cable (A1450).  It does not work at all; it is not even recognized by the phone (I tried it on 2 phones) for charging, and I tried 3 different power sources.  A replacement is on its way to me. 

DOES THE ADAPTER CONTAIN A DAC?
I found at least one reference online to the Apple brand of adapter containing a built-in DAC.  I find it hard to believe.  There seems to be no room at all for a DAC chip.  But Apple states that it supports analog audio output

A few years ago, I built a DAC for my home stereo, and it has capacitors and a power supply.  The DAC chip itself was substantial.  I can see that Lightning could provide power, although certainly not much but perhaps enough; but even if there is a functioning DAC chip, it seems that it must be doing an absolutely minimalistic job.  Could this be any better, or even as good as the chip in the phone? I'm not convinced this route is better or as good as plugging in to the 3.5mm jack. 

IS THERE NO WAY TO GET ANALOG AUDIO FROM LIGHTNING?
It seems there is consensus that no analog signal can come from the Lightning port.  I bring this up because I do not consider myself to be in the know on the specs, and some people seem to have a really impressive understanding of the Lightning port, and I would like to have a good grasp of some of the basics, like being certain that Lightning will not output analog audio. 

WHAT FILE TYPE IS ON MY PHONE?
All my music on the iPhone is ripped from CDs into Apple Lossless, and I do not check the box in iTunes to convert to lower resolution.  Does this mean my phone stores the music files in the Apple Lossless format?  Or is it converted into something else?

IS THERE A BETTER SOLUTION?
I found a device called the iSimple Jamlink that converts Lightning to analog audio output using a DAC ($50 on Amazon).  I am planning to use one of these in my car, in the hope that the DAC will be better than those contained in the phone or inside the Apple adapter. 
I came across another brand of 12v DAC that accepts Lightning (I thnk it was called iStreamer).  What HiFi rated another product from this company, I believe it is HRT, as their top DAC under $300, so that helps to legitimize the prospective quality of their 12v product.  It's $179 on Amazon.  While I'm not keep to spend more money, $179 is not a ridiculous price on a decent DAC, so I wonder if this route is worth the investment.

Thank you for any responses.  I realize that makes several questions, not just one.  In Googling around, I find so much speculation, that I am hoping to get just a few facts and reasonable opinions, and another thread I just read on this forum contained several impressive contributions.  Thanks again!

Apple Lightning and digital/analog output

Reply #1 –
There is no analog signal in a Lightning connector.  The actual protocol is just an encrypted form of USB2 down a different connector, so its all digital.

If you want to do Lightning to RCA you will need a Lightning compatible DAC that has a line out.

Apple Lightning and digital/analog output

Reply #2 –
First, what is it about a DAC that you think requires it to be so large? Your phone has one in it. The Sansa Clip has one in it and that device is TINY. You would also be hard pressed to find better audio quality than you'll get from that little DAC in the that little player.

Whether from your phone's 3.5mm jack or from a DAC in a lightning adapter, the signal will be about the same. The 3.5mm output might technically be a little noisier on a scope but I doubt you would be able to hear an audible difference between that and the output from a quality DAC attached to the lightning port.

Quote from: catalogguy on
A few years ago, I built a DAC for my home stereo, and it has capacitors and a power supply. The DAC chip itself was substantial.


Those caps were likely required due to the power supply, or simply needed due to the design of that specific DAC chip. The chip you described as substantial is probably just the packaging to house the pins. The actual IC was likely very, very small, and the lithographic process used to make that chip was likely 20 years behind the one used to make the chips in the iphone.

Quote from: catalogguy on
While I'm not keep to spend more money, $179 is not a ridiculous price on a decent DAC, so I wonder if this route is worth the investment.


I would venture to say no. Prove to us that the quality of the DAC in the iphone is so poor as to audibly adversely affect quality then we'll reconsider this. I'm no fan of Apple by any stretch, but all the measurements I recall seeing indicated the audio output from the iphones is typically well beyond transparent to anything with human DNA in it.

Apple Lightning and digital/analog output

Reply #3 –
Thank you so much to both of you for the informative replies. 

I have Googled up a site with a photo of the DAC contained with the Apple adapter cable, and it is tiny!
http://www.chipworks.com/en/technical-comp...-30-pin-adapter

I will just be impressed with the miniaturization and the DAC's capability, and leave it at that.

Apple Lightning and digital/analog output

Reply #4 –
I play music through that same 30 pin adapter and it works fine. I have a 30 pin to RCA cable that goes into this adapter, cable into my amp and it works very well. I plugged the USB into a charger so it charges while playing music.

Just to check, do you notice that the phone disables volume control? That is an indication that the phone has recognised the DAC and sends a digital audio signal to the Lightning connector. The only thing I recall is that you have to have at least iOS 7 because that's first iOS to come with the intelligence to recognise the DAC.
Every night with my star friends / We eat caviar and drink champagne
Sniffing in the VIP area / We talk about Frank Sinatra
Do you know Frank Sinatra? / He's dead

Apple Lightning and digital/analog output

Reply #5 –
Hi Maurits,

On my old iPhone, as you mention with your phone, the volume on the phone became nonfunctional once the 30 pin cable was plugged in (but this was plugged in directly into the old phone - no adapter). 

The issue with the new cable went beyond the audio signal; it would not even charge the phone, and there was no recognition from the phone when the cable was plugged or unplugged.  I tried the cable on 2 phones and with a variety of connections, but the cable was just DOA.  The seller has promised me that a new one is on its way to replace the defective cable. 

On my old phone, the RCA cables were not connected to the power, so the phone did not charge during playback.  However, this sounds like a terrific feature, and I look forward to connecting power for the new phone. 

Thanks again!

Apple Lightning and digital/analog output

Reply #6 –
What I'd do is get one of those cables from 30 pin to RCA and USB. Then get a decent USB charger of around 2Ampere, the ones also recommended for tablets. Although the iDevice regulates the charging current it draws (which I think is 1A max), the fact that the charger is overspecced seems to help because it can provide both the full charging current and the current to run the phone/play the music while charging etc. It is now the fastest way in my house to charge my phone. 
Every night with my star friends / We eat caviar and drink champagne
Sniffing in the VIP area / We talk about Frank Sinatra
Do you know Frank Sinatra? / He's dead

Apple Lightning and digital/analog output

Reply #7 –
Quote from: Maurits on
What I'd do is get one of those cables from 30 pin to RCA and USB. Then get a decent USB charger of around 2Ampere, the ones also recommended for tablets. Although the iDevice regulates the charging current it draws (which I think is 1A max), the fact that the charger is overspecced seems to help because it can provide both the full charging current and the current to run the phone/play the music while charging etc. It is now the fastest way in my house to charge my phone. 


You know, for around $100 you can get a new head unit with a USB port that does USB Audio.  I believe USB Audio will give you a line out AND will charge the phone from one connector.

I bought my wife an Alpine radio and was quite impressed with the overall quality of the sound over USB.  I'm thinking of getting on for my car as well.