iPod measurements

[antonik]

Quote:

Originally Posted by yeeyy Looking at the Crosstalk figure, it is now confirmed that my previous finding on iPod poor performance on headphone output.

As you may see from the graphs the channel separation off-load is very good. However there is an obvious series resistance (several Ohms) present in the ground connection to the jack socket, so the separation gets worse if the load impedance is reduced.

Alex

 

[bangraman]

I'm working my way through some electronica with the Sony MDR-G74SL on both the iPod Mini and the Zen Micro. The felt bass feeling that I get is not significantly less on the Mini. So there's a question mark over how relevant these bass fall-off measurements are in real life.

http://reviews.cnet.com/Sony_MDR_G74...2.html?tag=tab

 

[antonik]

Quote:

Originally Posted by bangraman The felt bass feeling that I get is not significantly less on the Mini. So there's a question mark over how relevant these bass fall-off measurements are in real life.

The Mini could be different from G3 iPod in this respect. Now there are several tiny HP amplifier chips available which will work without output capacitors all together. What breez has measured on iRiver shows that it is likely to be the case there, so perhaps the Mini is similar? However the LF roll-off is only part of the problem, high-ish distortion could be more of a distraction. On the other hand, resistance in the common earth on the socket works as some kind of crossfeed circuit...

.

Alex

 

[lindrone]

So you tested the G3 iPod, not the G4, correct?

 

[Jahn]

this follows my fumblings -

G3 40gig Ipod sounds best with a line-in and an amp, next best with my KSC-35 hooked into a 75ohm adapter to the headphone out, then worst just with a KSC-35.

 

[antonik]

Quote:

Originally Posted by lindrone So you tested the G3 iPod, not the G4, correct?

Yes.

Alex

 

[yeeyy]

Quote:

Originally Posted by antonik As you may see from the graphs the channel separation off-load is very good. However there is an obvious series resistance (several Ohms) present in the ground connection to the jack socket, so the separation gets worse if the load impedance is reduced. Alex

That's why I stated Headphone Output. At Line Output iPod is measured better but still not as good as Zen Xtra.

 

[antonik]

Quote:

Originally Posted by yeeyy That's why I stated Headphone Output. At Line Output iPod is measured better but still not as good as Zen Xtra.

I am not sure that there is a big difference in crosstalk between no-load headphone output and line out - in my measurements this particular bit was limited by the measuring setup, including cables, so -90 dB was probably the system limit. On Stereophile graphs this figure is a bit better for midrange. Still 90 dB is very good and should not present any problems. However 40-60 dB under load is somewhat poor, thought it would not be really noticeable when you listen to the music.

Alex

 

[Zoide]

Quote:

Originally Posted by yeeyy That's why I stated Headphone Output. At Line Output iPod is measured better but still not as good as Zen Xtra.

Isn't the Xtra the one for the reputation for very poor build quality, though? I thought I read somewhere that owners were having problems like the faceplate coming off, etc.

 

[yeeyy]

Quote:

Originally Posted by Zoide Isn't the Xtra the one for the reputation for very poor build quality, though? I thought I read somewhere that owners were having problems like the faceplate coming off, etc.

I am comparing the Sound quality.

 

[halcyon]

iPod does have a significant bass roll-of from it's headphone output to a low impedance load.

This is indeed a measured fact. I've seen several measurements from various sources, using both AP system 1 and System 2 set ups.

The results have been shown in various German and Finnish audio and technical magazines. Measurements done by competent audio engineers with more than 20+ years of experience in audio equipment measurement alone (i.e. they do it daily for their living, they are not any quacks that can be attacked with ad hominems). I've posted about this before with references.

The Stereophile measurement is the ONLY one that doesn't really show this to the extent that it exist in all the other reliable measurements I've seen. BTW, Stereophile uses afaik Miller Audio Research gear, which is known to be less accurate than AP System 2.

Still, I believe it's the lack of proper test load the explains why Stereophile measurements do not show the bass roll off issue.

As for RMAA accuracy, I can't vouch for it, but I have passed the comments on to the developer.

 

[bangraman]

For the 5G, the falloff is greatly reduced. To a near-identical level as the iAudio X5.

 

[wanderman]

Quote:

Originally Posted by bangraman For the 5G, the falloff is greatly reduced. To a near-identical level as the iAudio X5.

wouldn't it better to refer the other h120 which was tested in this thread or is the h120 better?

edit: nvm I saw the other thread

 

[wanderman]

dbl post