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Audio quality of iPod 5th Generation (Video)

Recording of SE test sequences, played back by Apple iPod 5th Gen.This audio player is from 2005. Like almost all portable players by Apple it was remarkable for its audio quality and usability. Many early iPods are still in use and can be easily found on eBay. Such well-known “anchor” players from the past are important points on the global AQ map, SE is trying to build.

 

 

 

 

 

 

 

 

 

Figure 1. Recording of SE test sequences, which include both technical signals and various music material (the test set "Variety"). Processing of these records results in standard df-measurements presented on Fig.2 below.

 

 

Df-slide showing location of various test signals (including 2 hours of music) on Df scale according to their levels of degradation

Figure 2. Df-slide with audio measurements of the iPod. It can be compared with Df-slides of other devices on the Portable players page.

 

Artifact signature of iPod 5th differs substantially from modern audio solutions by Apple. Sine 1kHz is distorted 10dB higher than sine 12.5kHz. Relative position of triangle signals on Df scale indicates that odd harmonics prevail in the distortions. Almost all tech. signals with this iPod show worse Df levels than with modern ordinary spartphones. High output impedance. Definitely this device has noticeable sound character.

Conclusion:

Thanks to Wolfson audio chip with relatively high level of waveform degradation iPod 5th (Video) has its own distinctive sound signature (slightly harsh mids, transparent highs). Some music types/genres can benefit from this artifact signature, some other will not. As a result there always be lovers and haters of this player. Starting from iPhone 4 and iPod 6th Gen. Apple uses much more transparent/neutral audio chips from Cirrus Logic. High-Ohm headphones are recommended for this iPod 5th.


 

Appendix

All-off
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35
iPod 5th - Variety - 1 iPod 5th - Variety - 2 iPod 5th - Variety - 3 iPod 5th - Variety - 4 iPod 5th - Variety - 5 iPod 5th - Variety - 6 iPod 5th - Variety - 7 iPod 5th - Variety - 8 iPod 5th - Variety - 9 iPod 5th - Variety - 10 iPod 5th - Variety - 11 iPod 5th - Variety - 12 iPod 5th - Variety - 13 iPod 5th - Variety - 14 iPod 5th - Variety - 15 iPod 5th - Variety - 16 iPod 5th - Variety - 17 iPod 5th - Variety - 18 iPod 5th - Variety - 19 iPod 5th - Variety - 20 iPod 5th - Variety - 21 iPod 5th - Variety - 22 iPod 5th - Variety - 23 iPod 5th - Variety - 24 iPod 5th - Variety - 25 iPod 5th - Variety - 26 iPod 5th - Variety - 27 iPod 5th - Variety - 28 iPod 5th - Variety - 29 iPod 5th - Variety - 30 iPod 5th - Variety - 31 iPod 5th - Variety - 32 iPod 5th - Variety - 33 iPod 5th - Variety - 34 iPod 5th - Variety - 35
-20.6 -16.7 -16.0 -23.2 -16.7 -17.3 -22.5 -16.3 -14.2 -14.3 -20.0 -15.5 -18.2 -17.8 -25.6 -18.0 -24.5 -16.4 -23.3 -28.8 -23.1 -14.7 -17.3 -11.8 -18.5 -16.9 -15.0 -11.2 -16.8 -17.6 -16.7 -12.0 -24.2 -17.2 -19.6

 

Figure 3. Diffrograms of 35 tracks of the test set “Variety”, played back through iPod 5th (Video). They show level of waveform degradation of the musical signal divided into 400ms chunks (one pixel each, max. degradation is Red). Median Df values of the tracks are indicated. Click a track to open in full size for quick comparison with similar tracks from another device. More about diffrograms → Diffrogram: visualization of signal differences in audio research.

 

Figure 4. Dendrogram showing similarity of artifact signatures of tested players. The shorter the link between two players, the more similar their artifact signatures.

Dendrogram showing similarity of artifact signatures of tested players

 

It looks like average linkage for the dendrogram better reveals clusterization of players according to their artifact signatures. So it will be used instead of complete linkage from now on.

 

 

Table 1. Underlying matrix of Spearman distances between artifact signatures for the dendrogramm. The Spearman distance = 0.1 is critical for relation of Df measurements to subjective scores. For the players that have similar artifact signatures (distance < 0.1) their perceived sound quality correlates well to df-measurements performed with substantial amount of real-life music material (histogram medians).
    (1)    (2)    (3)    (4)    (5)    (6)    (7)    (8)    (9)
 (1) Apple iPad mini 2
(2) HTC Desire C
(3) HTC Desire C (ba)
(4) Shanling M2s
(5) Shanling M2s (HighGain)
(6) Shanling M2s (gradual)
(7) Apple A1749 adapter
(8) OnePlus 6
(9) Apple iPod 5th (Video)
 0      0.0619 0.0972 0.0445 0.0446 0.0334 0.0374 0.0111 0.0578
0.0619 0      0.0655 0.0149 0.0147 0.0174 0.1494 0.1029 0.0017
0.0972 0.0655 0      0.0651 0.0651 0.0660 0.1710 0.1306 0.0612
0.0445 0.0149 0.0651 0      0.0002 0.0024 0.1378 0.0887 0.0112
0.0446 0.0147 0.0651 0.0002 0      0.0025 0.1379 0.0888 0.0110
0.0334 0.0174 0.0660 0.0024 0.0025 0      0.1229 0.0752 0.0140
0.0374 0.1494 0.1710 0.1378 0.1379 0.1229 0      0.0095 0.1455
0.0111 0.1029 0.1306 0.0887 0.0888 0.0752 0.0095 0      0.0988
0.0578 0.0017 0.0612 0.0112 0.0110 0.0140 0.1455 0.0988 0

 

 

 

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For almost 20 years SoundExpert is the home for innovative audio measurements and research. Newly developed listener-centric audio metric combines instrumental measurements with listening assessments and helps to perform both more efficiently.

Since 2001 more than 10 000 volunteers participated in distributed blind listening tests on Soundexpert website. Sound quality ratings of 100+ codecs were computed thanks to their time and efforts. You can still take part in them.

Recently we developed a new method for instrumental measurements of audio equipment. It is based on the new audio metric and helps to examine technical performance of an audio device in great detail. Furthermore all audio devices can be grouped according to their sound signatures. The measurement procedure was fine-tuned during two years of beta-testing with 30+ portable devices. Now it is mature enough for production environment. First few tested players can be found on Portable players page.

I hope this new audio metric will attract more audio engineers and enthusiasts as it opens new field of audio research where objective and subjective are not separated anymore. Further advance in the research requires many more different audio devices to be tested - a serious challenge for our non-commercial research project. Fortunately portable players are good test subjects for this research, even the old ones. That's why I need some help from our volunteers again. If you have such old/previous/ex digital portable audio player or a smartphone that was marketed as "HQ audio inside", if it is fully functional but not in use anymore, please, consider donating it to SoundExpert. Its df-measurements will appear on the portable players page. Then it will be either kept for research purposes or sold off supporting the project additionally (or given away to some music lover if it can't be sold for some reason). I'm going to refund your postal expenses but can't confirm this right now. Please, contact me for further arrangements.

Manufacturers of portable devices can order df-measurements for their products. The cost of the work will be equal to retail price of the device. I will buy it and perform standard df-measurements. If you decide I will not publish results during a year.

Today building a comprehensive audio quality map of various audio devices on the market can be done by ourselves - audio consumers. And it's not hard indeed. In the end this will free up some time for listening and discussing Music, not technology )).

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SoundExpert Founder