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Review: iPod touch 2G - one year on - SQ, performance and How-to

post #1 of 53
Thread Starter 
This will be a review in parts to be shared here at headfi and at TouchMyApps with slightly different aims. Here, I won't get into any applications, multi-media, battery life, or anything else; sound, music functions, and performance is all I will focus on.

The 'review in parts' will tackle several issues, but one at a time so that I won't forget anything as there are many good and not so good issues to ponder. Today, I went through my entire headphone collection, testing amps, cables: everything; with a certain degree of surety, I can say that the iPod touch is a fantastic performer with a few issues. Some arise from firmware, and others from the output stage, but overall, it has very few audio flaws.

I will try to leave the review open so that it cannot be contested by iPod haters, Apple bashers, etc.; the review will focus on real-world tests and hard evidence of performance only. Still, if you want to bash the iPod touch, this thread, or me, you can -- that is your prerogative; however, the review will be balanced with experimental evidence in relation to other portable players including the Cowon S9, Sansa Fuze, and a few others.

It will not go into the wishy-washy 'liquidy' mids; and will focus solely on performance when driving headphones.

Look for: best volumes to amp the headphone output; how to set up the iPod touch for LOD/amp play, and how to ensure you get the best performance when listening to music through the headphone output.

*****

Part One: How to set up the iPod touch for best music playback (Week of 23 Novembe 2009).

Firstly, I will state this: since generation 2, the iPod touch has became quite a different animal. Gone was Wolfson, the chanting cry of many audiophiles; the new chip from Cirrus Logic does some things better and some things worse than the old Wolfson. What it does better is provide: lower noise floor, a nearly black audio background, lower distortion, and NO bass rolloff with any dynamic earphone, no matter the impedance.

What it does worse is obvious depending on the music in play. Firstly, a much lower noise floor with extremely low distortion with most earphones means the sound is cleaner, another audiophile word which gets thrown around without much thought. The problem with a clean signal is that it loses a sense of atmosphere, of warmth - which are often offspring of distortion. The venerable X5 from Cowon is known as an atmospheric player which is warm and liquidy. Both adjectives can also be applied to many vinyl setups: the main reason is distortion. The iPod touch 1G had goodly amount of hiss (though less than a few players) and more distortion than the current 2G touch. I took a suite of hardware tests 2 years ago to see if my ears were hearing what I thought they were. They were. But after upgrading my computer, I lost those tests. Under load, the touch 2G will output about 5-10 less distortion than the 1G, sometimes much less.

For this reason, you need to think about what music you listen to and what sound you like. The touch 1G, though flat and more neutral than the vast majority of competitor's players, was warmer than the 2G. So, if you want more warmth, more emotion, you will need to pair the 2G with an emotional earphone which is somewhat harder to drive and which forces distortion. Most balanced armature earphones force even the best players to distort, and the iPod touch 2G is no exception.

2ndly: the iPod touch has no support for custom EQs. There is some conjecture that when using an LOD and amp, that custom EQs work - I will explore this in this review.

TO CREATE A CUSTOM EQ you must go to iTunes, open the EQ and set it to your preferences. Then, you must rename it to the exact spelling of default EQ setting. If you don't, then it will just make a new EQ setting. The iPod only stores default settings, but as we will see, even new settings don't transfer over to the system. The graphs below demonstrate the iPod running default No EQ and Flat EQ (which I adjusted as illustrated). As you can see, there are no changes.

So, how do we enjoy EQ on the iPod? Unfortunately, it has to be done the hard way: using MP3Gain or AAC Gain to lower the song's gain which causes stressful EQ settings to distort the iPod's signal. Though iTunes and the iPod have worked together for many years, there is NO OTHER lossless method of enabling EQ on the iPod without suffering distortion. Unfortunately, custom EQ still isn't possible.

[space reserved for output charts]

Headphone memory and Wifi
The iPod touch has headphone memory based on impedance. When working, it will remember a volume setting based on impedance. So, when you use several different headphones, you won't have to constantly change volumes - just by plugging in a new headphone, the volume will change back to the setting. When it works, it is convenient, but things also go awry. For instance, a memory setting can be upset and the iPod confused. Certain dynamics will remain, but overall volume will be reduced or set way too high independent of the of the volume slider. To avoid this, reboot the iPod touch before listening to music. This will ensure clean signal which is optimised for one headphone alone.

Also, WiFi affects the signal negatively. This is especially evident when using the Line out with an amp; buzzing and interference will be detectable with sensitive earphones. If you just want to enjoy music, disable Wifi and turn off the screen. Keeping the unit plugged into the computer or USB also introduces extra noise into the circuit, audible in noise and pops (again with sensitive earphones). In other words, the best sound is straight from the battery without outside interference.

Optimal headphones and the differences between amping LOD or HPO signals
The iPod touch 2G was the first iPod after the Shuffle 1G to suffer very little at the hands of low ohm earphones. While saying there is no effect at all would be a mistake, this model drives low ohm iems very, very well. However, that prowess is limited to dynamic type earphones. I have tested this with earphones from 16-600 ohm. The touch 2G suffers NO bass roll off, very little distortion increase, very little channel narrowing, and can sustain loud volumes even when connected to the 600 ohm Beyerdynamic DT880.

Moving onto balanced armature earphones is another story, however. From single to multiple driver earphones, there are obvious, audible effects. Some, such as the JH13Pro induce bass roll off, others such as the Fit Ears 333 induce mid range suck out. Most of them cause audible channel narrowing and distortion levels to rise. The fact is that the touch 2G isn't that great of a DAP for balanced armature use.




If you have dynamic earphones, using an amplifier with EITHER the HPO or and LOD, may (depending on amp model), gain: grit, silk, liquidy mids, volume. It may also soften the touch 2G's sharp sound. But overall, dynamic earphones don't benefit as much from amping as balanced armature earphones do. Of course, amps can introduce their own problems: some are not able to drive balanced armature earphones very well. Others hiss considerably with any earphone. If you plan to use an amp, you should buy one for the earphone type you intend to use.




If you have balanced armature earphones, you will need to choose an amp which can drive them, otherwise, you are gaining next to nothing. You may gain the above signature elements such as: silk, grit, liquidy mids, etc., but suffer your earphones to similar problems: bass roll off, channel narrowing, etc..




Amps work via HPO or LOD. There are a few advantages to the LOD, but it isn't universally better. The iPod touch 2G has very low hiss from its HPO, but it does introduce more to the signal. But at the same time, it doesn't pick up radio interference as badly, even with a cheap 3,5 cable. Amping the HPO out means you will have to set the volume manually. One notch from the top seems to be the sweet spot: no deleterious effects of distortion.
post #2 of 53
CAN'T WAIT TO SEE THE REVIEWS!
post #3 of 53
Bookmarked! Looking forward to comprehensive review.
post #4 of 53
Bookmarked X 2!! Just what I wanted to read up on. Thanks!
post #5 of 53
Subscribed, w/instant email notification!!!!
post #6 of 53
Thread Starter 
I see there is another Depeche Mode fan - now I am nervous!
post #7 of 53
Depeche Mode, + my (soon to be purchased) iPhone = nirvana!!!!
post #8 of 53
Where's the review?
post #9 of 53
Thread Starter 
coming this week -- still gathering information for part one so I will have a succinct review. Please be patient, sorry for the wait.
post #10 of 53
I'm interested in this because I have an RE2 and I want to upgrade to a 3rd generation iPod Touch. From what I understand the 3rd gen is the same as the 2nd gen. I am currently using a 1st gen iPod Touch 16gb. I was just wondering if there is a change in sound quality from 1G to 3Gen.
post #11 of 53
Thread Starter 
There is, but I am unsure as to the sound change between the 2G and 3G as I have only heard the 8GB third gen which by all assumptions, is the same hardware as the 2G. The difference in sound between the 1 and 2G is three-fold. First, there is almost no hiss. Second, there is no bass roll off unless you are driving impedance-switching balanced armature earphones. Third, the sound is colder than the somewhat lush 1G (somewhat).

Overall, I prefer it, but there are times when the 1G (despite its flaws), sounds better.
post #12 of 53
What do you mean by colder? I assume, no hiss and no bass rolloff are 3rd gen attributes?
post #13 of 53
Thread Starter 
The 3rd gen iPod touch has similar levels of hiss as the iPod touch 2G. By colder, I mean the Wolfson chip in the original 1G is 'softer' for a lack of better terms. There is more distortion, but it does a good job where it counts. The 2G and 3G have very low levels of distortion, but I am much more sure of the 2G.
post #14 of 53
I've tried everything to get my 1G Touch to sound better than it did on day one, to no avail. Something like the ND-S1 into a good DAC+amp might help, but short of that I think its a lost cause - my GF has badgered me for it from day one, and this December her wish will come true.
post #15 of 53
Thread Starter 
congrats - you get rid of the thing you hate!
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