On the other hand acc. to this guy here: http://marlene-d.blogspot.com/2012/10/review-sansa-clip.html
Rockbox works fine with 44.1 but appears to be 'broken' on 48kHz with Clip+.
I am wondering if you get the same results on 48kHz with the clip zip.

Yes. Something might be horribly wrong with 48 kHz under Rockbox. Will report back. Need to use ARTA also, since RMAA currently doesn't handle well 2i2 ASIO drivers past 44.1 kHz. It may introduce some slight unexpected gain also in 44.1 kHz.

I got results more similar to Nw this time with ARTA, even with the 32 ohm and ~0.4V levels, so that's that. Don't think RMAA is bad, but I guess one needs to learn the quirks of the tool.

Even with with the stock FW @ 48 kHz and either way with 44.1 kHz, standard IMD calculation seems to neglect certain crap in the treble region. THD might definitively be much higher with two tones than IMD calculations might suggest.

Will report back tomorrow...

Yup, dual booted for a while this thing today...

Well, rather disappointed at what turns out to be SMPTE IMD 60Hz 7kHz. It seems the % values reported typically include only the 2nd and 3rd order effects. Some talk about it here:

http://www.ap.com/kb/show/414

The problem I see is that the Zip and the Clip throw a LOT of curd at higher order IMD products, even when not broken by Rockbox + 48kHz cuz in that case shit hits the fan.

Furthermore, the Zip is a biatch to measure due to the pitch error issue. This pitch error is BOTH FW and rate dependent. Some of the measurement packages expect the 2nd and 3rd order effects at certain frequencies. Well, the pitch has the effect of moving the distortion components a few Hz off and things can look uber-great or uber-bad. No clear way to sync things up with a DAP since it's clock is not slaved to the interface ADC. Did the best I could there so here it is.

First a few corrections. According to my grain of salt measures...

Zip Rockbox max voltage out: 0.957 Vrms
Zip Stock max voltage out: 0.556 Vrms

Some bit about bits

Zip Rockbox: It can take 24 bits, but it measures virtually identical to 16 bits. Like SD said, best guess is the resolution is limited to 16 bits and the FW does something to make 24 bits play by removing LSBs.

Zip Stock: Placed a few 24 bits tones but the Zip refused to play them.

Pitch and 48 kHz

The pitch on the stock FW seems a bit more off than when using Rockbox (both are off BTW). However, 48kHz files work with the stock FW. Rockbox fucks things up with 48kHz files... Funny thing is that even if Rockboxed Zip manures a 48kHz file, SMPTE IMD reported % distortion doesn't look too bad given curd doesn't happen to hit expected 2nd and 3rd order IMD distortion location. IMD + Noise might catch it though.

So for 393mVrms @ 32 ohm here are some THD (1kHz) and IMD (60Hz + 7kHz 4:1) measures.

Stock FW @ 44.1kHz

THD: 0.0317%, IMD: 0.133%





Stock FW @ 48kHz

THD: 0.0316%, IMD: 0.133%





Rockbox FW @ 44.1kHz

THD: 0.0276%, IMD: 0.122%





Rockbox FW @ 48kHz

THD: 0.0276%, IMD: 0.122% (Awesome, yeah right)





As far as the IMD results with 48kHz with Rockbox, d2 and d3 are negligible compared to the weirdness around 3kHz, 800Hz, and pretty much all the crap everywhere.

Thanks....
Nice measurements and confirmation to not Rockbox mine .... ('cause of quiet a few 48kHz files mixed with 44kHz on my players)

I noticed some weird things when reproducing squarewaves with the Sansa's as opposed to the FiiO X3.
Should turn it into an article and post my findings.
The Sansa clip sport has HIGH amounts of 500kHz residu in there, the Fuze does not.
The attachments have scope images of a few tests with various players and tones.
They are 'raw' plots but their filenames show its relation, maybe some technical minded folks can make something out of it. 

I noticed during my efforts in measuring my Fuze that distortion drastically lowers (at least those 'sideband alike' issues) when NOT loading the HP out.
As I use always use my Fuze with an external amp there is no load and max amplitude issues are solved.

Despite its shortcomings I still like my Fuze but prefer the X3 (which froze on me yesterday again even with the latest FW)

So, since this was a Sansa Zip and Creative Zen thread here are some comparos w 32 ohms and ~0.068 Vrms (max Creative Zen can provide)

Frequency Response (Zip is red / Zen is white)



THD (1 kHz)  (Zip is red / Zen is white)
(Zen is 0.0032% THD)
(Zip is 0.0537% THD)



SMPTE 60 Hz 7 kHz 4:1  (Zip is red / Zen is white)
(Zen is 0.012% IMD)
(Zip is 0.249% IMD)



On paper...

+ Distortion: The Zen seems to have the upper hand.

+ Power Ouput: The Zen max output swing is about 0.068 Vrms into 32 ohms or 0.14 mW (slight correction from first post). Zip can do 0.556 Vrms into 32 ohms or 9.67 mW (cleanly w stock FW, Rockbox can do 28 mW but distortion increases). So Zip can get much louder.

+ Output Impedance: Zip is like 0.61 ohms and Zen is like 0.94 ohms.

+ Frequency Response: Zip is ruler flat in the audio range. Zen rolls off a bit depending on load. The lower the impedance of the cans, the more the roll off.

Both are OK players... Well... I still don't like the load impedance dependent roll of of the Zen and it's limp dick max power output, but distortion looks good. The Zen can play .m4a video which is kind of cool. Rockboxed Zip can play some video games, but the screen is a fraction the size of the Zen and much lower quality. I think the Zen is more restricted in audio format support.

Based on some results, the Rockboxed Zip suffers when playing 48 kHz and 96 kHz (Ok with 44.1 kHz and 88.2 kHz) files which I largely don't have, but if one does, it is a consideration vs sticking to the stock FW. The stock FW however will not play 24 bit files at all. Rockbox at least removes the LSBs and let's them out reasonably well. Zen does not recognize FLAC, but can play 48 kHz, 88.2 kHz and 96 kHz WAVs Ok.

Zen is AFAIK no more.