[yonder]

I read some review about ipod touch 2G rmaa testing ( http://ko.goldenears.net/board/index.php?mid=GR_Mobile&document_srl=16343 ), and there is a dramatic difference in measurement THD% and IMD+ Noise% in depending on headphone impedance (0.0026% for 32ohms and 3.172% for 16ohms (THD), and 0.0063% for 32ohms and 0.595% for 16ohms (IMD+ Noise). In other review where measurement were performed for ipod touch 3G, using 15ohm resistive load, results (0.0057% THD and 0.011% IMD+ Noise) are much closer to testing touch 2G with 32ohms, in first review. If both of device have same audio chip (cirrus logic cs4398) why touch 2G had much worse test results?

 

[shigzeo]

Hey Yonder, I test with earphones not a dummy load. The earphones I test with are rather difficult to drive: Provate 332 or Earsonics SM2. Dummy loads don't run variable loads while earphones do. An earphone rated at 32 ohm will jump all over these depending on the frequency and pressure it is channeling.

 

[yonder]

I can't find your test here... I find on this site ( http://www.touchmyapps.com/forums/showthread.php?340-iPod-touch-2G-RMAA-%28Right-Mark-Audio-Analyzer%29-comparison-with-Fuze-V2 ) link for some rmaa tests, but, I can't get permission to access the page...
 
...and still, I do not understand... why such a big difference between 2G and 3G in audio tests? Why 2G has a big distortion (THD) over 16ohms headphones?
 

 

[shigzeo]

The images there are attachments in the forum. You have to be a registered member to see them. I used to post them in my Flickr, but that was a waste of space for a photography (not to mention the money I pay for it each year). I am working on a new system to show the RMAA and SQ Wave results better than before. 
 
16Ω is much harder for a portable source to push than 32Ω or 64Ω as it requires more current than the higher Ω for the same voltage. That's why. But THD is rarely a BAD sounding artefact. Consider people purchase valve amps and vinyl for the sound. While an artefact (farther from the source material), it may sound more 'natural' - distortion that is.

 

[yonder]

thanks for explanation, shigzeo,
I, actually, want to buy some good (used) player, for listening music mostly, and now decide between 2g (40-50e) and 3g (60-80e). If both of them have a similar sound I would buy a cheaper...
Different tests on sites confusing me, here for example ( http://blog.faberacoustical.com/2010/ios/iphone/ipod-touch-3g-headset-io-frequency-response/ ) 2G have a better performance than 3G...
btw, I am registered member (vlaya), but they wrote: you do not have permission to access this page...

 

[shigzeo]

vlaya, I'll have to look into that. I'm going to rehost the stuff at a different location as TMA isn't optimal. To be honest, no where is, but oh well. 
 
2/3 are pretty much equal. 4 is where things got different. For dynamic earphones of any type or maker, both are pretty much as good as it gets. 4G made balanced armature playback variance a thing of the past.

 

[yonder]

ha, finally, I bought touch 2G!
with my sennheiser px 100 II touch sounds very good
however, I still try to find somewhere rmaa audio test tables...

 

[shigzeo]

If they are so troubling, I'll see if they are still on my computer and upload them to ohm image. I'm trying to organise things that way. It will be easier and more direct. Cheers.