Just out of curiosity, how are you measuring the quality of the iPhones, iPods? You listen to each with a few types of headphones and see which device produces the best sound? As is well documented on the site, the headphones make a big difference. I'm testing each of my iPods/iPhones and have many to choose from, although the really old ones will not make the cut simply due to lack of storage. All those 8 gb first edition Nanos (even an iPod Mini) . . . Anyway, thanks, all . . .
Agreed that the iPod 5g sounds best, straight out of the headphone jack. Noticeable difference over the Classic and iPhone 4s. The 4g is next for me, followed by an old iPod Mini.
Not everyone agrees that the iPod Video sounds the best out of the headphone jack. I prefer the output of the iPhone 4/4S and any model of iPad. Here are some observations I've collected over the years.
The iPod Video (Gen 5/5.5) headphone out has a capacitor-coupled output. On lower-impedance headphones, there is audible bass rolloff. On 16-ohm 'phones, it's down a few dB by 40 Hz--just like on most Cowon DAPs. Older iPods have the same problem, and it's actually worse on the iPod Mini, especially the first model that came out. Newer iPods and iPhones don't have this problem.
The iPod Gen. 3/4/5/5.5, Mini, and Classic models have at least a 5 ohm output impedance on their headphone amplifiers. That means that they don't deliver a uniform frequency response to low-impedance headphones that have impedance that varies with frequency. On something like a PX-100 or an HD238, the midbass response goes up a little bit--and it's already excessive on those cans. On SE530/SE535 there's a hole at 5 kHz. TF10 and XBA-4 have even worse deviation. In contrast, the output impedance is under 2 ohms on the iPod Nano (6th generation), iPhone 4/4S and iPad. These all deliver a more linear response, especially the iPhone 4 and the new iPad, which have 0.9 ohms and 0.8 ohms source impedances, respectively.
The iPads and newer iPhones also have lower distortion when driving lower-impedance loads, sometimes an order of magnitude lower than the iPod Video. Combined with the lower output impedance, they are stiffer voltage sources and thus, behave much more like ideal voltage amplifiers.
At maximum volume, the old iPods clip their output. And this happens even without a load attached. Hook up the headphone output of an iPod Video to an oscilloscope and you will see the flat tops of the waveforms. Sometimes, it sounds really bad. This doesn't happen on new iDevices until the load goes down to 16 ohms. And even then, you can dial the volume back and the maximum undistorted output is still a good 0.55-0.6V rms for a full-scale sine wave, which is still higher than what a Sansa Clip/+/Zip can deliver, let alone an iPod Video.
Old iPods get around 0.9 Vrms undistorted output with no load, which is under maximum volume. It's closer to 1V--maximum volume--with the iPads and new iPhones, even with a 32 ohm load. With some quiet tracks, insensitive headphones like the HD600 need more than 1 V. But with some kinds of music, the HD600 can get loud enough near maximum volume. In this case, the HD600 draws so little current, and therefore, is an easy load to drive. It's really a walk in the park for the iPad--the noise and distortion figures stay very low as if it were nothing--i.e., an open circuit. Here, the iPad headphone output sounds very close to dedicated amps in a level-matched comparison. The same can be said for the old iPods as long as you don't have the volume too high.
On newer iDevices, the headphone output is pretty much a transparent unity-gain buffer at maximum volume. It's cleaner than the line outs of many CD and DVD players. In some cases, the low output impedance makes the headphone output work better than the line out on the 30-pin connector. For example, a passive volume control can become a relatively low-impedance load for the line out, and the effects of loading might be audible. But the same passive volume control is practically an open circuit for the headphone out. Do a blind, level-matched comparison between the line out and the headphone out going to the same amp. It's very, very close. The new iPhone 5 isn't really missing a thing by not having an analog line out.
The reconstruction filter is different on the new models... But that's another story, along with the Wolfson-is-better myth. For most practical purposes, it's no big deal.
Im not agreeing with your post in the sense of agreeing as I dont have nearly as many iPods or iDevices as you have mentioned but I do applaud the effort you put into an excellent self post on what you have personally measured and observed.
*slow clap* commencing
I have owned and "heard" many iPods but none with the train of thought of analyzing the differences and also i wasnt aware of audio back then as well.
They all sound very different from one another. Sometimes I like the sound of one better than the other.
I did try a pair of Sennheiser 300CX Iems yesterday and I have to say I fell in love with the combo. Why I have not found out about these headphones before I really don't know? Defiantly the best way to get a sound improvement out of Apple products regardless of DAC inside.
Through line out, all iPods sound the same- perfect. The only thing that differs is how the iPod works with various impedence cans throgh the headphone out.
Through line out, all iPods sound the same- perfect. The only thing that differs is how the iPod works with various impedence cans throgh the headphone out.
This is my experience as well (from the few I've owned).
I am highly suspicious of anyone who claims otherwise, or claims that ipods have bad sound quality (quite a cliched thing to do amongst "audiophiles").
That? It depends on if you compare an iPod to something else but yeah however i am more disturbed by people that come in and say to give them suggestions but no Apple products and then they name something that fits an iPod.......
Impedence issues are more a function of the cans than they are the player. The iPod is designed to be a portable player, so it's optimized for portable headphones. You can plug in big honkin' home cans, but it was never intended to be used that way.
If you really want to use big headphones, all you have to do is get a line out dock and a nice little cmoy amp. Bingo. It doesn't matter if you have the first gen or the most recent Touch. Now you've got sound to rival your home stereo system.
Yep, the Dacs are plenty good enough considering an iPod is everywhere, everyonr has one regardless of price. An iPod is somewhat of an American right these days rather than a beg and get thing... Not that I am saying a parent should lay out $300 for one, just that so many have it.
Here I am in class listening to a beautiful Opera/pop piece with some IEMs while I go online to check on business updates and RSs news and can also do some gaming. An iPhone is a friend to an Apple friendly audiophile
Some iPhone 5 notes:
I got a chance to play with one for a but only for a very short time. I actually hope I got some of the measurements wrong. We'll see if Sonove or GE or anyone else can confirm these.
Maximum volume is a little higher on the iPhone 5: 0.37 dB over the iPhone 4S. This puts it a little over 1 Vrms for a full-scale sine wave.
iPhone 5 playing a pure tone going to a spectrum analyzer shows a skirt at the bottom of the spike. It's not present on the iPhone 4S. Could it suggest that one of them has more random ______ than the other? The level is very low, but I'm sure a few will imagine hearing a difference and attribute it to this. Maybe some of the guys over at the Portable Source Gear forum who were crying about not getting a Wolfson this time. Airplane mode didn't make a difference. I wish I could have taken a picture.
This, however, will sometimes have a much bigger effect (paste it into Wolfram Alpha):
0.482*15.4/(R+15.4)=0.397
or
0.320*15.4/(R+15.4)=0.264
If you're using the Earpods, which are pretty much 40+ ohm resistors, then it won't matter. BTW, you can even use them, a splitter, a test tone, and quick and dirty measurements with a DMM to verify if my numbers are in the right ballpark.
I tried plugging my iPods into my main amp using the line out some time ago and was impressed how good they were. Driving headphones, a good amp will benefit. One of my favourite rigs at the last show in Tokyo was my iPhone connected to an ALO Continental and I've had a few amps pass through here, including an O2 I just built which are pretty good too.
I reckon that, if I was listening to the same music I did when I joined Head-Fi years ago, all I'd need over my iPhone would be just a decent amp. Since I use my computer though for listening, I still reckon a DAC and amp is good for best results, but now there are so many good, inexpensive units available that one doesn't have to spend much to get "good" sound.
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