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

[elfary]

Good to know than even switched off in settings there is still this stupid EU limitation... Not many know this.

I noticed that my iPad Air goes louder than my iPhone 6.

Is it a good idea of connecting a Topping NX1 to the iPhone 6 or will it destroy the perfect sound output of the iPhone (if we put the slight volume increase aside) ?
I'm not sure if I can hear any differences (I use the NX1 with the HD558)

 
Not much people know because nobody has tracked down the actual regulation that enforces capping. Once you've read it you understand it all (The colored volume squares, the diminished output and that there are 2 volume limits in place but user is only allowed to turn off one of them -the 85db one-).
 
Non european iPhones sound exactly as loud as iPads (which are not sold capped because...the sell with no bundled earphones hence no way to stick to CENELEC nonsenses).
 
If you don't have volume problems iPhone sound output is excellent and suited for critical listening.

 

[yuriv]

These iPhone 6S measurements might be interesting to some of you. This is for model MKTG2LL/A with iOS version 9.0.2 (13A452).
 
 

Open-circuit voltage, right channel, maximum volume
 
 
It's exactly 1V, a little lower than the maximum volume of the 5S. The volume control is very coarse: -3 dB and -4 dB steps:
 

Voltage, mV	Attenuation from max, dB
1000	0
709	-2.99
450	-6.94
320	-9.90
204	-13.81
146	-16.71
91.7	-20.75
58.8	-24.61
38.8	-28.22
24.3	-32.29
16.6	-35.60
10.1	-39.91
7.	-43.10

 
It goes from maximum volume to mute with 16 presses of the volume down button. 8 down has the volume level indicator halfway through the scale, 38.8 mV or roughly 28 dB down.
 
 
Here's what happens with 16 ohms across each channel:
 

Right Channel Voltage, 16-ohm load on right channel only
 
 

Right Channel Voltage, 16-ohm load on each channel
 
 

Left Channel Voltage, 16-ohm load on each channel
 
 
The impulse response and some square waves: 
 

Impulse response
 
 

1 kHz square wave
 
 

Rising edge of 60 Hz square wave
 
 
 
Here's what happens to at lower voltage levels, which is where you usually have it when listening to earphones:
 

Right channel, open circuit voltage, 5 clicks down from maximum.
 
 

The same, but with a 16-ohm load on each channel
 
Let Wolfram Alpha do the work: http://www.wolframalpha.com/input/?i=201*16.2%2F%28R%2B16.2%29+%3D+156
 
It should be ok with the usual dynamic-driver IEMs, low-impedance dynamic-driver headphones with relatively flat impedance vs. frequency graphs, e.g., ATH-M50x, and BA IEMs that sound better with added serial resistance, e.g., ER4P, UE600 with foam tips, Apple ME186LL/A. 
 
With really sensitive IEMs that have crazy impedance vs. frequency curves, I guess you could build the following circuit to make them work better with the iPhone 6S (or for that matter, those "premium" portable music players that have it much worse).

The iPhone 6S will see a near-constant 16-ohm load, the IEM will see slightly less than 1 ohm source impedance, the frequency response going to the IEM will be much flatter, and the signal-to-noise ratio will be improved.
 
 
I'll see if I can take measurements to show what happens to the noise level when scrolling, switching apps, etc.

 

[elfary]

These iPhone 6S measurements might be interesting to some of you. This is for model MKTG2LL/A with iOS version 9.0.2 (13A452).
 
 

Open-circuit voltage, right channel, maximum volume
 
 
It's exactly 1V, a little lower than the maximum volume of the 5S. The volume control is very coarse: -3 dB and -4 dB steps:
 

Voltage, mV	Attenuation from max, dB
1000	0
709	-2.99
450	-6.94
320	-9.90
204	-13.81
146	-16.71
91.7	-20.75
58.8	-24.61
38.8	-28.22
24.3	-32.29
16.6	-35.60
10.1	-39.91
7.	-43.10

 
It goes from maximum volume to mute with 16 presses of the volume down button. 8 down has the volume level indicator halfway through the scale, 38.8 mV or roughly 28 dB down.
 
 
Here's what happens with 16 ohms across each channel:
 

Right Channel Voltage, 16-ohm load on right channel only
 
 

Right Channel Voltage, 16-ohm load on each channel
 
 

Left Channel Voltage, 16-ohm load on each channel
 
 
The impulse response and some square waves: 
 

Impulse response
 
 

1 kHz square wave
 
 

Rising edge of 60 Hz square wave
 
 
 
Here's what happens to at lower voltage levels, which is where you usually have it when listening to earphones:
 

Right channel, open circuit voltage, 5 clicks down from maximum.
 
 

The same, but with a 16-ohm load on each channel
 
Let Wolfram Alpha do the work: http://www.wolframalpha.com/input/?i=201*16.2%2F%28R%2B16.2%29+%3D+156
 
It should be ok with the usual dynamic-driver IEMs, low-impedance dynamic-driver headphones with relatively flat impedance vs. frequency graphs, e.g., ATH-M50x, and BA IEMs that sound better with added serial resistance, e.g., ER4P, UE600 with foam tips, Apple ME186LL/A. 
 
With really sensitive IEMs that have crazy impedance vs. frequency curves, I guess you could build the following circuit to make them work better with the iPhone 6S (or for that matter, those "premium" portable music players that have it much worse).

The iPhone 6S will see a near-constant 16-ohm load, the IEM will see slightly less than 1 ohm source impedance, the frequency response going to the IEM will be much flatter, and the signal-to-noise ratio will be improved.
 
 
I'll see if I can take measurements to show what happens to the noise level when scrolling, switching apps, etc.

Very interesting! Thanks

It'd be great if you can assess the background emi noises both objectively and subjectively...


If the tonality it's not right, then nothing else really matters.

 

[yuriv]

According to the data sheets at InnerFidelity.com the UE600 is one of the most sensitive headphones or earphones they have measured. So I used that one. With some older players, I can definitely hear some hiss on the UE600 even when there's nothing playing on the player. On the iPhone 6S, I can barely hear the noise... until I start doing other things on the phone. Then, it's very noticeable. It's clearly audible even when no app is making a sound. I was hoping that the phone would be quieter once the music started playing, but nope, no luck there, especially in music with quiet passages. Ask Apple Music to play any recording of the Goldberg Variations, and the noise will be audible during the aria unless you stop messing with the phone. With the likes of Minaj and Bieber, it's not that much of a problem.
 
The Etymotic ER4PT and Apple ME186LL/A aren't nearly as sensitive, so the noise isn't that noticeable with them; much less so with added series resistance. IEMs that are close to the UE600 in sensitivity usually have crazy impedance vs. frequency curves, and most of the time, added series resistance will make their acoustic response worse. It's probably best to avoid such IEMs when using the 6S. The voltage divider I described in my previous post should take care of both problems somewhat.
 
I don't have my measurement gear with me this weekend, so I cranked the gain on a Focusrite Saffire USB 6 and looked at the output in Room EQ Wizard. We're only interested in the relative noise levels, so these uncalibrated charts should be ok for now. What I'm hearing sounds much worse than the 3+ dB of noise level increase shown below. The crude measurement system's self noise is probably obscuring what's really going on.
 
 

Screen off, file playing: -56.4 dB FS on the Focusrite with the gain knobs turned to the maximum.
 
 

Screen on, not busy, user not messing with the UI: -56.0 dB FS
 
 

Playing file, left at app switcher screen: -53.3 dB FS
 
 

Playing file or not. It's very noisy on the UE600 when the 6S is charging: -43.3 dB FS
 
 

Slightly quieter when no file is playing and user isn't interacting with the UI: -57.6 dB FS
 
 

No file playing, but left at the app switcher screen: -53.8 dB FS
 
 
The graphs look pretty much the same when I removed the UE600 and the iPhone 6S was playing straight into the recorder, which has a very high input Z. 
 
BTW, this phone is model N71AP (Samsung A9 chipset, instead of TSMC, model N71MAP).

 

[elfary]

Pretty ugly stuff for an Apple iPhone headphone out. I have owned iPhone 3Gs, iPhone 4s, iPhone 5s and iPhone 6 and never ever did i hear any emi noise even with Shure se530/5 or Westone UM3x that are as sensitive as an iem can get.

So seriously bummed by that Apple headphone port in the 6s. And a symptom that this company is slowly departing from excellence not only in the software area but now in the hardware front as well.


If the tonality it's not right, then nothing else really matters.

 

[a_recording]

  The crude measurement system's self noise is probably obscuring what's really going on.

 
Hey Yuriv, it's Lachlan! Nice work on the measurements, I'm looking forward to seeing more results. We're discussing the EMI noise and your measurements in this thread, so it's nice to get some actual numbers.

 

[djmuzi]

Maybe it will help when somebody writes a bug report to Apple (or it will only eventually help the next iPhone)

 

[elfary]

Tried an iPhone 6s with my Shure SE535.

There is a distinct buzzing when you mess with the iPhone while listening to the headphone port.

Can't hear a darn thing while performing same actions on my iPhone 6.

This is bad shielding all the way.

An unthinkable regression for Apple. More even so on the 's' iteration of the perfectly shielded iPhone 6.

On the bright side my wallet is smiling this year.


If you don't get tonality right, nothing else matters.

 

[S W Dunlevy]

Hi,
   I have E-mailed the 3 addresses on the Vorbis Opus site. I simply asked them how much power a custom CPU would need in core-mark or dhrystone, I mean, it goes up to 504/bps. Has someone already run a test and I've not found it?
 
I know that the iPod used 2x90MHz ARM7TDMI which got modified until a 75MHz dual-core CPU with shared cache did the trick. They started with 3 32K banks and upped it to 4 i.e. 129K.
Then they added stuff that needed lots of power and so custom 312MHz dual-core CPU.
 
 
Have people compared floating-point with fixed point audio quality?
 
It just seems that this codec has NOT been fully tested?
 
I'm thinking that while Apple can have 2 (or more) CPUs with a common cache, I'm looking for a low-energy CPU for a pocket audio player - for charity.

 

[SergeSE]

Here is the objective measurements of the following models:
 

1. iPhone 3G
2. iPhone 4
3. iPhone 4S
4. iPhone 5
5. iPhone 5S
6. iPhone 6
7. iPod classic (2009)
8. iPod shuffle 2G
9. iPod shuffle 4G

 
http://soundexpert.org/portable-players

 

[RRod]

  Here is the objective measurements of the following models:
 
http://soundexpert.org/portable-players

 
Any plans to measure the Pono?

 

[SergeSE]

   
Any plans to measure the Pono?

Actually I have plans to measure everything

including Pono and other top quality players; the only problem - how to get them, I can't buy them all. So, at the moment I measure devices that I can ask from people around me. Most of these devices are well known and popular which helps to verify the new metrics. But in order to measure new models I need to cooperate with somebody else; thinking about that ...

 

[davidsh]

I like that you actually do a test with real music (eg. DSoTM). Might have a look at your testing methodology.. Some of the measurements shows surprisingly big differences.

 

[SergeSE]

  I like that you actually do a test with real music (eg. DSoTM). Might have a look at your testing methodology.. Some of the measurements shows surprisingly big differences.

http://soundexpert.org/news/-/blogs/visualization-of-distortion
http://soundexpert.org/documents/10179/11017/DiffLevel_AES118.pdf

 

[hogger129]

I don't think they sound bad out of the dock connector.  The headphone out sucks imo.