Positive Feedback ISSUE 59
january/february 2012

 

 

The Itty-Bitty 4th Generation iPod Shuffle and 24-bit Music Files
by Teresa Goodwin

 

This is not a traditional review of the iPod Shuffle, instead it is a report on its performance with high(er) resolution 24-bit lossless music files. If your interest is 16-bit lossless or lossy music files or comparison of features versus other portable digital players I will refer you to many of the traditional reviews on the internet. However we are audiophiles so we want the finest sound from all devices in our lives; with a digital player and quality replacement headphones high resolution music is possible on the go. 

16-bit music files unacceptable

I previously reported back in January 2011 that I deleted all 16-bit 44.1kHz music files from my Mac Mini's hard-drive because they didn't satisfy my craving for realistic, enjoyable music. All of my computer music files are now 24-bit. In addition I sold my 2nd generation iPod as I was not able load my high resolution music files onto it. I was considering getting a high resolution portable digital player, the ones that do 24-bit 96kHz PCM such as the Korg (which also offers DSD) however they were all recorders/players and cost more than I was willing to spend. In addition they were considerably larger and bulkier than the iPod shuffle.

I do however have all of my old 16-bit 44.1kHz music files on backup DVD-R's so I reloaded some of the better audiophile ones from labels such as Telarc, Reference Recordings, Mobile Fidelity Sound Lab, DCC, and Lyrita back onto my computer to hear how they sound on this new iPod Shuffle. I then loaded up a mixture of 16-bit and 24-bit music files onto the iPod Shuffle and went for a three mile walk. I quickly discovered the differences are quite profound, the 24-bit music files sounded like real music and occasionally gave me actual goose-bumps as I was walking, by contrast the 16-bit music files sounded lame and often quite uncomfortable.

It had been nearly a year since I had heard many of these 16-bit music files and they had the same sonic problems that caused me to delete them nearly a year ago. When I got home I listened to some of them from the computer and was so dissatisfied I once again deleted them from my computer which is now once again completely 24-bit.

24-bit music files on the 4th Generation iPod Shuffle

In my unproductive search for a high resolution portable digital player I discovered that newer iPods play 24-bit 48kHz music files, not as high resolution as I wanted but I did miss not carrying my music with me this past year, and the iPod Shuffle was less than $50 shipped so I ordered one.

This new iPod Shuffle handles most audio codecs, however I am interested in the 24-bit lossless ones and it offers WAV, AIFF and Apple Lossless. Apple Lossless is sometimes abbreviated ALAC (Apple Lossless Audio Codec) however since Apple and iTunes never abbreviate Apple Lossless as it does with all other codecs neither do I for clarity and those new to computer audio.

WAV and AIFF offer the unadulterated uncompressed music file so these are the absolute reference for sound quality, whereas lossless codecs such as Apple Lossless slightly alter the sound due to the process of unpacking the music file.

To my ears uncompressed WAV is the best sounding however I am not able to insert album artwork in the metadata field, thus my choices were between uncompressed AIFF and Apple Lossless. Basically Apple Lossless is bit perfect, the file is compressed and then uncompressed on the fly during playback, even though bit by bit identical to uncompressed WAV and AIFF, as noted above the actual unpacking of the file is what is said to account for audible differences. The sound quality of both AIFF and Apple Lossless is very close, although I find very small differences. The AIFF versions have a little more air, ambiance and slightly better transient detail while the Apple Lossless versions have warmer bass and a fuller midrange which I believe are consequences of the packing and unpacking the file as I can convert the Apple Lossless file back to AIFF using XLD and it will have to sonic qualities of AIFF once again. This also suggests that bits are not bits and a lot more is going on in digital audio than we will ever understand in our lifetimes.

That said, on my Mac Mini I use Apple Lossless as to my ears it is more exciting if only very slightly less realistic, this may differ between computers and DACs so I advise to experiment on your own before making a definite choice between the two. Another deciding factor was the hard-disc space savings benefit as Apple Lossless music files are 40% to 60% smaller than AIFF or WAV. However if you ever decide to convert 24-bit Apple Lossless back to AIFF don't use iTunes as it will convert it to 16-bit, instead use XLD (X Lossless Decoder) and in Preferences > Output Format > AIFF > bit Depth chose "24-bit". XLD is available as freeware.

I would never hook an iPod directly to an audio system since my computer's sound quality is considerably better, however as previously noted 24-bit 48kHz music files sound considerably better on an iPod than do 16-bit 44.1kHz music files of any type. Ultrasonic response is not reason as 48kHz only extends the high frequencies by 2kHz and transient response would only be slightly faster, the biggest improvement is in the audible range especially the mid-frequencies and the fact that 24-bit reveals many more intricate details making the music smoother, more realistic and enjoyable.

See http://www.positive-feedback.com/Issue54/high_resolution.htm  for an explanation for why 24-bit audio sounds more realistic than 16-bit audio.

Even though the iPod uses cheap DACs and even cheaper analog components, with a good set of headphones high resolution 24-bit music files clearly sound better. The greatest sonic advantage of the iPod with 24-bit over 16-bit music files is in the midrange, however the bass is fuller and warmer and the highs add a sparkle and tingle that 16-bit could never do. Also with 24-bit the soundstage is wider and deeper and projects a larger image inside my head. In short I see no reason to listen to 16-bit audio on my stereo or my iPod. 24-bit or DSD is all I need.

Getting ready to import 24-bit music files to the iPod Shuffle

Your music files including lossy up to 320 kbps (MP3, AAC) and lossless up to 24-bit 48kHz (Apple Lossless, AIFF, WAV) can be directly imported. If you have Lossless FLAC files these need to be converted to one of the lossless formats iPod supports listed above.

You will need to make 24-bit 48kHz versions of your higher resolution music files, this can be done with the above mentioned XLD. Open Preferences > Output Format > Apple Lossless > Sample Rate chose "48000 Hz".

Connect the iPod to your computer and in Options make sure that the following are NOT checked:

Enable Sound Check

Convert higher bit rate songs to 128 kbps AAC

Limit maximum volume

The idea of the option to convert high bit rate songs to 128kbps AAC is very outdated and one Apple needs desperately to change as even the iTunes store now offers 256kbps AAC. Personally even though I own a Mac Mini I don't like the sound of AAC at any resolution, to my ears 320 kbps MP3 sounds better, although at this point in my life it is also sonically unacceptable. What I propose Apple should offer instead is user selectable options for converting higher bit rates when auto-filling ones iPod with iPod's highest resolution as one of the options, currently 24-bit 48kHz. Until that happens I have to keep two music files on my hard-drive of higher resolution music I want in available for my iPod, for example a 24-bit 96kHz version for home listening and a 24-bit 48kHz version for the iPod.

One final step, replace Apple's crummy earbuds with high quality headphones

Replacement of the cheap earbuds is mandatory, however even with great headphones my Mac Mini routed through my tubed preamp sounds more realistic with smoother string tone and more comfortable sonics, on the other hand the iPod Shuffle is extremely small, light and I can take it anywhere I go.

The simple replacement with quality headphones makes this best overall portable device I have ever owned for listening to music away from home when it is playing 24-bit music files. I love its extremely small size which I can clip onto my clothing like jewelry.

The internet buzz

I did some google searches pertaining to listening to 24-bit music files on iPods and there is not a lot of discussion out there yet, however most who have compared both claim that 24-bit music files do indeed sound better on the iPod. On the other hand, some say iPods downsample 24-bit to 16-bit, however simply listening to the music files themselves proves that statement to be incorrect.

When the iPod is connected to your computer if you open up the "Get Info" tab on any of the 24-bit music files it will show the "sample size" as 24-bit and the "size" and "bit rate" will be the same as the same music file in your music library on your hard-disc. So if the iPod is downsampling it will be doing it on the fly as the music is playing and this just does not make sense to me, because if a digital chip can read a 24-bit music file I don't understand why it would not output the 24-bits it just read. Actually listening to the sonic difference between 24-bit and 16-bit music files on the iPod should dispel this notion.

Memory

This 2GB iPod Shuffle holds just under three hours of 24-bit high resolution music. For listeners who want more than three hours of high resolution music at a time, there is the 160GB iPod Classic which would give one up to 240 hours of 24/44.1kHz and 24/48kHz Apple Lossless music files. However I do not mind auto-filling with different selections each time I charge the iPods battery.

Final thoughts

Arnold's Overtures on Reference Recordings, which I purchased from HDTracks at 24-bit 96kHz and converted to 24-bit 48kHz using XLD for listening on the iPod shuffle was a real revelation proving that the Apple iPod can indeed be a high fidelity device. It is time the iTunes store reflects the advances made in the products Apple designs and begin offering 24-bit lossless downloads. And this may just happen as Apple has made Apple Lossless an open source codec which is said to enable them to offer 24-bit downloads in the iTunes store in 2012.

See: http://blogs.linn.co.uk/giladt/2011/11/apple-opens-the-way-to-24-bit-itunes.php

The first reason given for the existence of lossy codecs is so-called MP3 players, since modern portable digital music players now play lossless codecs thus MP3 and AAC are no longer required. The second reason is they claim most people cannot hear the difference, this I believe is because they have not been exposed to higher resolution music files yet. The third reason given is that the electronics in iPods and other portable digital music players is not good enough to hear the difference, this assumption is incorrect as the difference between 16-bit and 24-bit on Apple's cheapest iPod using their crummy earbuds is easily heard, and when one upgrades to high quality headphones, WOW! Thus in my opinion lossy music files and 16-bit digital should go the way of the dodo. The only music files that should be offered in 16-bit are those unfortunate ones recorded in 16-bit. All 24-bit PCM, DSD and high quality analog recordings should be offered as 24-bit downloads, on SACD, DVD-Audio or BluRay discs. In addition DSD and analog recordings can be offered as DSD computer downloads.

The iPod Shuffle is only 1.14 inches by 1.24 inches and 0.34 inches deep including clip and weighs 0.44 ounce. I will submit that the iPod shuffle when playing 24-bit music files is the first true audiophile product I am aware that one can buy brand new for under $50.

 

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