In another sign that Apple is not interested in high-resolution audio, they have introduced a new headphones specification that uses the Lightning port of your iPod/iPhone/iPad to output and input audio…digitally at 48 kHz. According to 9to5 Mac, a website dedicated to all things Apple, the new MFi (Made for iPod/iPhone/iPad) specification removes the requirement to use the traditional “mini jack” (the 3.5 mm stereo analog plug that has been in use for decades) and pushes audio bi-directionally to and from the headphones.
The standard output will carry stereo audio at 48 kHz and allow a microphone or other digital signal to travel the other way (a microphone or other transducer). I couldn’t find any reference to the word lengths in the piece by 9to5 Mac but they do point to a Wolfson DAC converter as a component that manufacturers will have to support (at least at the basic level of the connection…more below). The datasheet on the DAC lists audio performance at 106 dB SNT (A-weighted’), which translates to 18-bits…I found it curious that the datasheet didn’t actually state the word length but it does handle all “common audio sampling rates between 8kHz and 192kHz”.
So why is Apple limiting the resolution to 48 kHz when the chip that will reside inside new headphones will clock higher? Perhaps Apple is not so interested in high-resolution audio after all.
The connection to your headphones will switch from analog, using the 3.5 mm jack, to digital through the Lightning connection. This is a fundamental switch that dooes much more than offload the conversion of digital to analog signals from the phone. This opens up tremendous opportunities for headphones manufacturers…like Apple, now that they have acquired Beats. Despite the fact that Beats headphones are not highly regarded for sound quality, they do dominate the headphone market and upgrades can be expected.
For example, the new connection could enable remote control of volume, transfer of health related data (i.e. heart rate, hydration level) or other functionality through iOS. They haven’t activated the new capabilities but iOS 7.1 and higher devices will benefit from this update in the future. I also believe this would open the door to high-resolution audio headphone sets, provided the device has the right type of files.
There will be two different configurations of Lightning connected headphones. The Standard Lightning Headphones is the base package with the Wolfson chip mentioned earlier. The Advanced Lightning Headphones specification adds additional DSP processing to the equation. Think noise cancellation, surround processing, speaker or headphone modeling (make your Beats headphones sound like Stax…now we’re talking), upconversion and dynamics control. Once you get into the digital domain and pair it with a powerful DSP and some clever algorithm, you’ve moved way past the traditional model.
These are just some of the benefits of swapping a long-standing analog connector for a digital pathway. The connection also allows power from the Apple device to drive the headphones (if necessary) and also the other way around. As I have learned over the past couple of days in Cambridge, using my iPhone a lot drains the battery…I’ve resorted to using an external power charger. The new headphones could have high capacity batteries on board. The headphones would also be able to receive firmware upgrades if connected digitally.
This is a much bigger deal than virtually every report I read on the topic. It wraps the entire sound reproduction ecosystem under a single digital model that happens at the last possible point in the signal path. Meridian did it years ago with “digital” speakers and now Apple is leading the way with headphones. In this light, the Beats purchase makes more sense.
The bad news is that the Standard Lightning Headphones configuration, which will likely be the dominant flavor for a while, won’t handle better quality audio. Although, you wait and see…the 48 kHz number and 18-bit word lengths will have the labels and download sites claiming that everything at that spec is “high-resolution”.