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What is the sound quality of iPhone, iPad, iPod (Touch)?

Discussion in 'Sound Science' started by dlangendorf, Sep 12, 2012.
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  1. nick_charles Contributor
    Only your sanity [​IMG]
    reginalb likes this.
  2. krismusic Contributor
    Agreed! After a few years on here, there's not much of that left!:)
  3. krismusic Contributor
    Well I got the Dragonfly. I like the results plugging it into the 6S except for the clicks and pops of interference even in airplane mode. Strangely, I don't like the sound as much from the 5S. No interference but the sound is not as rich IMO. Either placebo or an electrical mid match?
  4. krismusic Contributor
    Has anyone found an inline DAC/amp that the 6S does not cause interference with?
  5. thewatcher101
    I found the dragonfly black do very little in terms of sq on the iphone 6s, and mines did not have any clicks or pops. The only thing I notice was the bass rolled off earlier in the dragonfly black.
  6. krismusic Contributor
    I quite liked the Dragonfly Red with the 6S except for horrendous clicks and pops.
  7. yuriv
    Apple's Lightning to Headphone Jack adapter, aka The Dongle.
    It's $9. So how bad could it possibly be?
    2nd column: Apple Lightning to Headphone Jack adapter, attached to iPhone 6S
    4th column: Apple Lightning to Headphone Jack adapter, attached to iPad Pro 9.7"
    All measurements at maximum volume, no load, and with iOS 10.
    More accurate distortion measurements appear below.
    The frequency response from the same set of measurements. They remain flat for all devices with a 16-ohm load on each channel, measured when the volume is lowered.
    AppleLightningtoHeadphoneJackfromiPhone6S1kHzsineatmaxvolumenoload2.png AppleLightningaudioadapter1kHzsinemaxvolumenoload.bmp
    Apple Lightning to Headphone Jack adapter playing 1 kHz sine wave from iPhone 6S, no load.
    Apple Lightning to Headphone Jack adapter playing 1 kHz sine wave from iPad Pro 9.7", no load.
    iPhone6Sheadphoneout1kHzatmaxvolumenoload2.png iPadPro9.7headphoneout1kHzatmaxvolumenoload2.png
    Compare that to the iPhone 6S headphone out on the left and the iPad Pro 9.7" headphone out on the right.
    AppleLightningtoHeadphoneJackfromiPhone6S1kHzsineatmaxvolume16ohmsbothchannels2.png AppleLightningaudioadapter1kHzsinemaxvolumebothchannelsinto16ohms.bmp
    Apple Lightning to Headphone Jack adapter playing 1 kHz sine wave from iPhone 6S, maximum volume, 16 ohm load on both channels
    AppleLightningtoHeadphoneJackfromiPhone6S1kHzsinevolume1clickdown16ohmsbothchannels2.png AppleLightningaudioadaptervolume1clickdownbothchannelsinto16ohms.bmp
    Volume one click down: Apple Lightning to Headphone Jack adapter playing 1 kHz sine wave from iPhone 6S, one click down from maximum volume, 16 ohm load on both channels
    AppleLightningtoHeadphoneJackfromiPhone6S1kHzsineonsetofclipping16ohmsbothchannels2.png AppleLightningaudioadaptervolumelowereduntilleftchannelhaslessthan1percentTHDbothchannelsinto16ohms.bmp
    Apple Lightning to Headphone Jack adapter playing 1 kHz sine wave from iPhone 6S, 16 ohm load on both channels, onset of clipping. I used the volume control slider to get the distortion just under 1% on the left channel. It's not easy to be really precise, but it's at a level between maximum volume and one click down.
    SMPTE IMD, no load
    CCIF IMD, no load
    Playback of 16-bit, 44.1 kHz J-test file
    Playback of 24-bit, 48 kHz J-test file
    AppleLightningaudioadapterimpulseresponse.bmp AppleLightningaudioadapter1kHzsquarewave.bmp AppleLightningaudioadapter60Hzsquarewavefakestepresponse.bmp
    Impulse response, 1 kHz square wave, rising edge of 60 Hz square wave "fake step response"
    So far, the performance seems to be in the same ballpark as the iPhone and the iPad. Here's some good news for those of you who like those crazy multi-driver balanced armature IEMs:
    4clicksdownnoLoad.bmp 4clicksdown16.6-ohmload.bmp
    Left: Apple Lighting to Headphone Jack adapter, 1 kHz sine, 4 clicks down from maximum volume, no load.
    Right: Apple Lighting to Headphone Jack adapter, 1 kHz sine, 4 clicks down from maximum volume, measured 16.6-ohm load on each channels.
    Therefore, http://www.wolframalpha.com/input/?i=200+*+16.6+%2F+(R%2B16.6)+%3D+196
    Which is lower than that of any other device running any version of iOS. It's almost an order of magnitude better than on the iPhone 6S.
    Subjective take on the noise level: I used the Ultimate Ears UE600 IEM to evaluate the noise level because it is very sensitive to hiss.
    The iPhone 6S had a good bit of audible electronic noise when it first came out. It was very noticeable on the task switcher screen and worse still when Siri was listening. This was a problem with IEMs like the UE600, Shure SE535, etc., but not for headphones, dynamic-driver IEMs, and less sensitive balanced armature IEMs like the Etymotic ER4P. With each update to IOS, the situation seemed to get better. Using IOS 10, I can still hear the noise on the iPhone 6S, but it's not nearly as bad as it was before. It's still there, but it's hard to notice when the phone isn't doing anything but playing music. The iPad Pro doesn't have this problem. It has more of a steady background hiss and it's quieter too.
    The Lightning to Headphone Jack adapter is more like the iPad. If you listen closely on a sensitive IEM, you'll hear it. It's also louder when the phone is on the task switcher or when Siri is listening. But it's much softer than the noise on the iPhone 6S headphone jack; it's also a soft, steady background hiss like on the iPad, not the irregular-sounding electronic noise on the iPhone 6S.
    This adapter can come in handy if you want to use a very sensitive IEM that has impedance that changes much with frequency. On the iPad it's not as useful because the Lightning connector is in a more inconvenient spot.
    EDIT 9/19: Added IMD graphs, cleaned up THD pics, corrected typos
    EDIT 9/24: Changed CCIF IMD graphs to show up to 30 kHz, added J-test results, recalculated output impedance with measurements on new setup.
    hakuzen, Chivbrguy, shigzeo and 3 others like this.
  8. elfary

    Awesome report that matches my subjective impressiones with SE846 attached.

    Could you post this valuable info on the headfi thread about iPhone 7 in the portable source gear subforum ?

    Alcohol is never the answer... But it certainly helps you forget the question.
  9. Double-A

    Just to confirm since I am not knowledgeable enough to read and understand the measurement portion of your post (sorry): did you find that the adapter has less than 1 ohm of ouput impedance?
  10. HiFiChris Contributor
    It was measured by a German tech site (less than 0.5 Ohms).

    Can you tell me whether the adapter works with the iPod Nano 7G or not?
  11. Double-A
    Yes, but I wanted to wait until that <1 ohm measurement was corroborated by a second source before I bought an adapter. Is that what "R" is supposed to represent in your link yuriv? Output impedance?

    I want to buy a pair of Shure SE215s, but I wanted to wait until I could afford a DAC/amp that has a lower output impedance than my iPhone 6. I don't know when that is realistically going to happen though because I earn minimum wage. If this adapter really does have less than one ohm of output impedance however, I could end my wait for the 215s.
  12. elfary

    As per Yuriv testing the output impedance of the dongle is 0'5 ohms that is why he commends the dongle for balanced armature setups.

    Alcohol is never the answer... But it certainly helps you forget the question.
  13. yuriv
    elfary, Double-A,
    Yes, that is the output impedance. It might even be lower and I have to be careful that the test leads' resistance isn't contributing to the figure. If there's any doubt, check this out:
    Frequency Response into UE600 (uncoupled)
    Some headphones have a voice coil inductance that can have a significant effect on the frequency response at high frequencies, especially on an amplifier with a high output impedance. On the UE600, the difference in frequency response between the iPhone 6S and the Lightning to Headphone Jack adapter is audible. It just so happens that I like the effect of the added resistance on this particular IEM. But I know that what's really going on isn't the behavior of an ideal voltage amplifier. There are many other IEMs that won't benefit from this so-called synergy. Because of the impedance interaction with their headphones, some people might conclude that the iPhone 6S headphone output is the better performer: "improved clarity!", ""tighter bass", "refinement!" Or maybe they'll just describe the Lightning audio adapter as slightly dull, uninvolving, and muddy. Lol.
    The SE215 won't be affected by this at all. Its impedance is typical of a dynamic-driver IEM--it looks like an 18-ohm resistor. So it doesn't matter if you plug it straight into an iPhone or the Lightning adapter. The frequency response (magnitude and phase) will be the same. If anything, the noise on the iPhone 6S will be first to have an audible effect, although I doubt even that will be a factor. So just plug it into the phone and enjoy!
    I don't have a 7th generation iPod Nano, so I can't test it. Maybe the next time I visit an Apple Store I'll bring the adapter. Maybe it needs IOS 10, maybe not? Your guess is as good as mine. Another interesting question is if it will work with a PC. Is it a class-compliant USB audio device with its own DAC? Many notebook computers have really awful audio; it would be a nice surprise if this dirt cheap Lightning adapter could be made to work with them.
    nrvenice likes this.
  14. elfary
    Thanks a lot for all the objective information you share with the community. Much appreciated and useful to avoid snakoil.
    I would be curious about an RMAA of the dongle driving a real earphone vs the iPhone 6s hpo driving that same headphone to catch a glimpse of THD, IMD and crosstalk in a real world scenario. It would be amazing if Cirrus Logic had been able squeeze a good crosstalk performance in such a tiny enclosure.
    In the added graph i noticed that the SMPTE IMD was noticeably higher in the dongle. What would be the impact of this in subjective listening versus iPad Pro or iPhone 6s ?
    Today I have done more listening with the Shure SE846 and the Westone W30 plugged to the combo dongle-iPhone 6s Plus and the sound is pretty darn good to these ears: clean and linear to boot. The dongle feels like an engineering statement from Apple.
    FTR in a quiet room i have been utterly unable of hearing any emi noise bleeding into the dongle (attached to the iPhone 6s Plus).
    last but not least: the dongle will only work in iOS 10 running devices. So not suitable for any iPod other than the latest Touch.
  15. krismusic Contributor
    I happened to be in an Apple Store today and bought the dongle. Two members of staff confirmed that it would work with the 6S. Nope. "This accessory is not supported by this device.".
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