ipod classic 7th gen specifics
Nov 8, 2011 at 12:51 PM Thread Starter Post #1 of 120
shrimants

shrimants

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I'm looking for a frequency response curve of ipod classic 7th gen, not 6th gen (unless there is no difference internally aside from HDD capacity.) Preferably with various types of load and also a line-out FR curve.

I'd also be thrilled if someone can tell what chips are used internally. Apparently the 5th gen ipod video used wolfson micro chips, though not the 8740 that everyone knows and loves, it was a 5789 or something like that. I think the latest ipod touch and iphone all use Cirrus Logic chips, dont know about the op-amps. No clue what the ipod classic 7th gen uses.
 
Nov 8, 2011 at 2:52 PM Post #2 of 120
I think it is the same chip as the 6th gen but I could be wrong. I will let others chime in.
 
Nov 8, 2011 at 9:33 PM Post #3 of 120
I hope it isnt....either that or I hope they changed the ipod 6th gen's op amp. There was a post I saw from a guy who ran a whole battery of tests on his ipod classic 6th gen and found its audio quality severely lacking, whereas his ipod 5th gen tested with flying colors.
 
Nov 9, 2011 at 1:28 AM Post #5 of 120
Hope you read the Vinnie thread.
 
Quote:
shrimants said:
I hope it isnt....either that or I hope they changed the ipod 6th gen's op amp. There was a post I saw from a guy who ran a whole battery of tests on his ipod classic 6th gen and found its audio quality severely lacking, whereas his ipod 5th gen tested with flying colors.
Click to expand...



 
 
Nov 9, 2011 at 1:46 AM Post #6 of 120


Quote:
shrimants said:
I hope it isnt....either that or I hope they changed the ipod 6th gen's op amp. There was a post I saw from a guy who ran a whole battery of tests on his ipod classic 6th gen and found its audio quality severely lacking, whereas his ipod 5th gen tested with flying colors.
Click to expand...



I don't know why people find the sound quality lacking. My 80gb 6g classic sounds just fine.
 
Nov 9, 2011 at 10:09 AM Post #7 of 120
My 7th gen sounds great too. There is of course the expected bass roll off, but even that is minor. And compared to ANY laptop headphone-out I've seen, the ipod sounds significantly better.

Ipod 6th and 7th gen defininitely dont use the wolfson chip. Wolfson chip was phased out by apple in favor of Cirrus Logic chip in the ipod touch and iphone. In the ipod 6th gen, according to Vinnie from the thread mentioned above, the ipod uses a proprietary DAC chip that was designed by apple. Vinnie also says that the ipod 6th gen uses a much simpler circuit than the ipod video. It does hard drive ->software audio decode ->dac ->amp -> headphone out.

Line out is right after the dac. He didnt say anything about what opamp was used or what sort of circuitry was implemented to control the volume of anything...They either have a seperate hardware circuit to control volume or the gain is applied to the origininal file in the software decoding phase. Since it is possible to adjust gain for individual files via their tags in itunes, i'm tempted to believe that the latter method is used.
 
Nov 9, 2011 at 11:29 AM Post #9 of 120
Doubt it. Someone posted on another thread that there is more noise on the wolfson vs the cirius. Not sure of the thread but I saw it yesterday while looking for the older classic threads.
 
And the line out does bypass the internal amp.
 
Quote:
pingupenguins said:
Well then my question is will classics ever have wolfsons?
Also a lod bypasses the pot not the amp, audio from a lod is max vol.
Click to expand...



 
 
Nov 9, 2011 at 12:03 PM Post #11 of 120
If the ipod had an analog volume control that was controlled by a potentiometer (twisty knob), that knob would be bypassed. But the knob is only changing the Current/Resistance relationship as it the audio goes into the amp from the dac. The DAC chip has line level volume, IE 0 gain applied (positive gain == higher volume than original, negative gain == lower volume than original sound file). Ipod doest have a potentiometer, it uses a click wheel to generate a digital signal, which is sent to the operating system. That signal, after being read, is converted to a negative gain applied to the song DIGITALLY, and then that song's data is sent to the DAC. either that or the signal goes from DAC to another circuit which controls the voltage of the opamp, and thus the op amp's gain.

As I said before, we dont know if the ipod classic actually has a cirrus chip inside. According to Vinnie, ipod classic 6th gen uses an apple proprietary DAC chip. Only ipod touch and iphone are confirmed to have a dac chip.

Here, i managed to do some googling around. I looked for pictures of the board, googled a marking, stumbled across FreeMyIpod, and that actually has all information sitting around right there. Im no good at reading datasheets because I only JUST got past basic analog circuits and am in digital right now. And we arent even going over SR latches or flip flops in this class so it basically doesnt even count as a digital electronics class.

http://www.freemyipod.org/wiki/Classic_3G
http://www.freemyipod.org/wiki/Hardware

Looks like we're using a cirrus logic chip in this ipod too. Can someone confirm if its the same chip used in itouch/iphone?
Also, considering they have a seperate chip for "usb charging", I can only assume that NXP PCF50635, the power manager, is the op amp. There are no immediately available datasheets for it.
EDIT: Classic 3g is identical in every way to the classic 1g and 2g. This man has measurements for the 6g: http://homepage.mac.com/marc.heijligers/audio/ipod/comparison/measurements/measurements.html
According to him, the ipod 6g is more crisp and detailed, but to him that is not considered an improvement ove the ipod 5g's "acoustic" tendencies. IE Acoustic music doesnt sound like acoustic music.

EDIT 2: despite him being very thorough with his measurements, there is a single sentence that more or less invalidates his entire expirement. He used the line input of his powermac. That is, by no means, a professional sound card of any degree. i cannot trust any of his measurements because of this. I have a dell vostro 1500 and the amount of crap I had to go through to get that little mini sound board working correctly was insane. I would never trust measurements that went into a stock motherboard line-in. Perhaps someone who has a pro-audio device can test with that thing's line input and post the results. He is right by saying that for comparison purposes, the measurements are valid, but I'm more interested in the actual performance than the comparison to ipod 5g since i dont have a 5g, I have a 7g. You can definately take 2 fish out of an aquarium and put them on a race track to see who wins, but even though the comparison is valid it is entirely useless.
 
Nov 9, 2011 at 3:52 PM Post #12 of 120
Check the current iPod Classic (model MC297) performance here http://sonove.angry.jp/
 
You are relying on old data from a different device. Current model MC297 is not the same machine delivered in 2007.
 
And to old urban legends lovers let me tell you that 5.5g Wolfson is far less accurate and has worse crosstalk performance than the Cirrus Logic built in these days.
 
Nov 9, 2011 at 10:33 PM Post #14 of 120
LOD is supposed to be bypassing the opamp. It is supposed to be the direct line out of the DAC chip itself. Based on the frequency response curves and personal listening, I would say the latest ipod classic is VERY worth buying unless you dont have a smartphone.

If you dont have a smartphone, I'd say ipod touch is way more worth it. Even in flac format, 64 gigs is way more than most need. Furthermore the added functionality of an ipod touch is well worth the extra money, especially because you can hack it to support FLAC if ALAC is somehow not your thing.

Personally I picked ipod classic over the ipod touch because
1) had an android device already
2) Ipod 5g was still alive and kicking since 2006 purchase
3) easily repairable/modable
4) massive support base for accessories
5) Disk mode
6) Future rockbox functionality
7) physical buttons make it operable in-pocket
8) very nice FR curves and statistics
9) No app/ads bullcrap to worry about. It does exactly what its supposed to: play music.
 
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