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iPod Classic vs. FiiO E7, Cirrus Logic vs. Wolfson
iPod Classic vs. FiiO E7
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skamp
post Apr 26 2012, 14:26
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There's a lot of hype in audiophile forums about how the new iPod Classic (with a Cirrus Logic CS42L55 DAC) sounds noticeably worse than older iPods (with a Wolfson WM8758 DAC). So I decided to compare my iPod Classic (with the Cirrus Logic DAC) to my FiiO E7, which has a Wolfson WM8740 DAC (with better specs than the WM8758).

I don't currently have a good soundcard with line inputs, so I had to use an old laptop to make the recordings, pending something better. I used Audacity (16 bit / 44.1 kHz) and recorded the iPod via its Line Out Dock and the E7 via its headphone out, both with the same 16/44.1 WAV file as a source. The song is Revenge! by Spoon, from The WIRED CD: Rip. Sample. Mash. Share., a compilation of songs licensed under Creative Commons "Sampling Plus", that can be legally shared.

I aligned the recordings and volume-matched them by running wavegain on them. Download from DropBox: A.flac, B.flac, C.flac.

C.flac is the reference file that was played back on both the iPod and the E7 when recording. I'm reluctant to say which is which regarding A.flac and B.flac, because aside from ABX logs, I'd like to know which file people prefer, if any.

This is the first time I do something like this, so let me know if my methodology is valid or if it needs an adjustment. The big question I have, is whether my recordings are good enough for the purpose of comparing the two devices, or if I need a better sound card.


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saratoga
post Apr 26 2012, 17:41
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QUOTE (skamp @ Apr 26 2012, 09:26) *
There's a lot of hype in audiophile forums about how the new iPod Classic (with a Cirrus Logic CS42L55 DAC) sounds noticeably worse than older iPods (with a Wolfson WM8758 DAC).


I've never heard that, and frankly its kind of a dumb thing to believe given that the WM8758 wasn't very good due to rolled off bass in the older iPods. I've actually got some old test results here from mine:



That is not very good by modern standards.

QUOTE (skamp @ Apr 26 2012, 09:26) *
This is the first time I do something like this, so let me know if my methodology is valid or if it needs an adjustment. The big question I have, is whether my recordings are good enough for the purpose of comparing the two devices, or if I need a better sound card.


Listening tests can be difficult under these conditions. Have you considered just using a tool like RMAA to measure distortion and frequency response while driving a load? Generally speaking, I think most people will accept that a device with moderately rolled off bass (the ipod 5G) is not doing as good as one with correct bass (the 6/7G).
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skamp
post Apr 26 2012, 17:58
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QUOTE (saratoga @ Apr 26 2012, 18:41) *
I've never heard that, and frankly its kind of a dumb thing to believe given that the WM8758 wasn't very good due to rolled off bass in the older iPods.

Note that audiophiles usually plug their headphones into an external amp, connected to the iPod via its line out, thus bypassing its internal amp. I don't know how much of a difference it makes regarding that issue.

QUOTE (saratoga @ Apr 26 2012, 18:41) *
Have you considered just using a tool like RMAA to measure distortion and frequency response while driving a load?

Unfortunately I can't install Windows on my old laptop (it doesn't have a CD-ROM drive, and I don't have a license). I do have Windows 7 on my new laptop, so it's something I could do if I decided to invest in a good USB device with a line in.


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saratoga
post Apr 26 2012, 18:09
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QUOTE (skamp @ Apr 26 2012, 12:58) *
QUOTE (saratoga @ Apr 26 2012, 18:41) *
I've never heard that, and frankly its kind of a dumb thing to believe given that the WM8758 wasn't very good due to rolled off bass in the older iPods.


Note that audiophiles usually plug their headphones into an external amp, connected to the iPod via its line out, thus bypassing its internal amp. I don't know how much of a difference it makes regarding that issue.


Line out doesn't really bypass anything on modern players. Its still the same output, except now into high impedance. So you get the white line instead of the blue or green. It will certainly help, but you're really just polishing a turd. Why bother with a DAC that struggles with included Apple earbuds when you could have one thats a lot better. Thats how I look at it anyway.

QUOTE (skamp @ Apr 26 2012, 12:58) *
QUOTE (saratoga @ Apr 26 2012, 18:41) *
Have you considered just using a tool like RMAA to measure distortion and frequency response while driving a load?

Unfortunately I can't install Windows on my old laptop (it doesn't have a CD-ROM drive, and I don't have a license). I do have Windows 7 on my new laptop, so it's something I could do if I decided to invest in a good USB device with a line in.


You don't have to install Windows or RMAA on the device doing the recording. Anything that can generate WAV files will work. Use linux, or even a good digital hardware recorder if you like.
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skamp
post Apr 26 2012, 18:27
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QUOTE (saratoga @ Apr 26 2012, 19:09) *
Line out doesn't really bypass anything on modern players.

Well for one thing, the line out is a hell of a lot louder (deafening) than the headphone out (which I max out with my headphones and mp3gain'ed MP3s), and volume control is disabled.

QUOTE (saratoga @ Apr 26 2012, 19:09) *
You don't have to install Windows or RMAA on the device doing the recording. Anything that can generate WAV files will work.

Right, IIRC I have to generate a test file with RMAA, play it back on the device and record it. I assume I can feed RMAA the recorded file directly? I'll check it out, thanks.


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saratoga
post Apr 26 2012, 18:59
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QUOTE (skamp @ Apr 26 2012, 13:27) *
QUOTE (saratoga @ Apr 26 2012, 19:09) *
Line out doesn't really bypass anything on modern players.

Well for one thing, the line out is a hell of a lot louder (deafening) than the headphone out (which I max out with my headphones and mp3gain'ed MP3s), and volume control is disabled.


No, line out == headphone out at 0dB (or maybe +1 dB, I forget). The maximum level is determined by the players voltage supplies, not the choice of output. Either can turn the gain up way past the max level, so when the line out volume and headphone out volume are set to just below clipping they'll have equal level.

QUOTE (skamp @ Apr 26 2012, 13:27) *
Right, IIRC I have to generate a test file with RMAA, play it back on the device and record it. I assume I can feed RMAA the recorded file directly? I'll check it out, thanks.


Yeah, run it and select "process wav" IIRC.
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skamp
post Apr 26 2012, 21:06
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QUOTE (saratoga @ Apr 26 2012, 19:59) *
No, line out == headphone out at 0dB (or maybe +1 dB, I forget). The maximum level is determined by the players voltage supplies, not the choice of output. Either can turn the gain up way past the max level, so when the line out volume and headphone out volume are set to just below clipping they'll have equal level.


Well, two things:
  1. My iPod is limited in volume because of a French law aiming to protect consumers against hearing damage. Like I said, when using the headphone out with mp3gain'ed MP3s, volume is set at maximum, and the result is just loud enough.
  2. I tried plugging various headphones into the LOD via an adapter. With 2 headphones (low impedance, high sensitivity), volume was fairly low, and bass was weak. Then I plugged in my Bose QuietComfort 15, which are headphones with active noise cancelling: volume was extremely loud, bass was huge.

What should I conclude from that experiment?

Also, I ran and published RMAA results for the iPod Classic, the FiiO E7 and the Samsung Galaxy Nexus. It's quite interesting.


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saratoga
post Apr 26 2012, 21:25
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QUOTE (skamp @ Apr 26 2012, 16:06) *
[*]My iPod is limited in volume because of a French law aiming to protect consumers against hearing damage. Like I said, when using the headphone out with mp3gain'ed MP3s, volume is set at maximum, and the result is just loud enough.


Sure, but that is just a software feature. You could easily remove that limitation. It has nothing to do with the actual hardware

QUOTE (skamp @ Apr 26 2012, 16:06) *
[*]I tried plugging various headphones into the LOD via an adapter. With 2 headphones (low impedance, high sensitivity), volume was fairly low, and bass was weak. Then I plugged in my Bose QuietComfort 15, which are headphones with active noise cancelling: volume was extremely loud, bass was huge.
[/list]
What should I conclude from that experiment?


That a line out should only drive a line in, and that a headphone out can drive either a line in or a pair of headphones smile.gif

You need to step back and understand what the difference between a line out and a headphone out is. A headphone out is a low impedance (ideally <<1 ohm) amplifier designed for driving lots of current into another low impedance load (16-300 ohms). Since Power = voltage *current, a headphone out can transfer significant power to a load.

A line out is a high(er) impedance output (typically 100-1000 ohms), designed for driving a high impedance load (typically a 10k or more). Thus a line out can not transfer significant power into a load.

When we talk about level, we're really talking about voltage. On the Ipod 6/7G, both the line out and headphone out have equal maximum level of about 1 Vrms. However, since the headphone out has easily100x lower impedance, it can transfer 100x more power. Thus when you connect your headphones, to you get far more power from the headphone output then the line out. When you connect the line in on your Bose QuietComfort 15, you transfer the same amount of power from both devices (since line in is a high impedance), and the same voltage. Thus you get the same volume. Or you would if you disabled the stupid voltage cap on your ipod.

Does that make sense?

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skamp
post Apr 26 2012, 21:51
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QUOTE (saratoga @ Apr 26 2012, 22:25) *
Thus you get the same volume. Or you would if you disabled the stupid voltage cap on your ipod.

Well no, like I said, I don't get the same volume at all. I still don't understand what's different about the QC15 in that experiment. And I did my research, the volume cap on the new iPods can't be disabled. The only way I guess would be to install Rockbox, but 1) I don't want to do that and 2) the port for current gen iPods isn't even stable yet.


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