Apple iPod Classic 4G

There was a time when Apple dominated the world of portable digital audio. Apple was by no means the first *, but it achieved such dominance that the utter disappearance of the iPod Classic from the market, now some seven years ago, must have then seemed inconceivable.

So let’s go back to 2004 and see what it was all about. In particular, how good was the dominant portable music player of the time, the Apple iPod Classic 4G. Indeed, let’s measure it and see whether it had overcome at least one performance deficiency of the original iPod.

 Apple iPod Classic 4G


  • Portable hard drive music player, dual HP/Apple branded, Model MP103
  • 40GB storage on 1.8-inch dual hard disk drives
  • Supports AAC, MP3, ALAC, AIFF (and perhaps more)
  • 5mm headphone output with adjacent proprietary connector for inline remote control
  • 51mm 160 by 128-pixel monochrome LCD display
  • Click wheel controller, hold switch
  • 30-pin proprietary connector, USB and Firewire compatible
  • 12 hours battery life
  • 8 grams
  • 6mm wide by 104.2mm tall by 18.7mm thick
  • That it still works is a testament to the quality of the original design and components. That it still works very well simply adds to that. Even new, though, not ideal for low impedance earphones or headphones. Yet, with higher impedance headphones, pretty respectable sound quality.
  • Can purchase on eBay with various modifications (eg, higher capacity SSD and new battery) for between $100 and $200
Apple iPod Classic 4G

    A touch of portable digital audio history

    By portable digital audio I’m talking about portable devices which play computer-style files containing music, not CD players, not MiniDisc players, not DAT (Digital Audio Tape) players. These digital audio players – DAPs – could be loaded up with music files which may have been downloaded (often illegally in the early days), ripped from CDs (often illegally, still) or perhaps even purchased.

    Remember, the iPod preceded the Apple iTunes store by more than two years.

    The formats were originally the then and still ubiquitous MP3, later supplemented by the iTunes standard AAC, AIFF (uncompressed Mac-compatible PCM), WAV (uncompressed Windows-compatible PCM) and ALAC (Apple Lossless Audio Compression). (I tried putting some WAV on the iPod, but the current setup on my Mac Mini didn’t seem to like it.)

    The 4th generation iPod Classic was introduced in July 2004 and replaced by the 5G in October 2005. The original version was available with 20GB of 40GB or storage. The latter, I’m told, although I haven’t dismantled the device to ensure this is true, simply used two 1.8-inch Toshiba hard drives instead of one.

    Now, I should make clear that back in 2004 – the copyright notice etched into the aluminium rear casing on this unit says 2004 – this was simply an iPod. “Classic” came in with the sixth-generation model three years later. But these days we retroactively refer to all the hard-disk-based models as “Classic” to be clear that we’re not talking about a Touch or a Shuffle or a Nano.

    Apple iPod Classic 4G rear

    The unit I’m looking at was kindly lent to me by the store manager of the Adelaide Addicted to Audio. It is his personal device and original, except for a recent replacement for a long-dead battery. No SSD upgrade. No other alterations. But I should note that, technically, this is not an Apple iPod at all. It is an “Apple iPod+HP” model. It seems that HP sold iPods for a little while, but they were “identical designs”. When Marek showed me his iPod, I would have begged to borrow it, but he graciously agreed without me having to abase myself.

    Why I didn’t review an iPod for most of a decade

    You see, I have a big gap in my iPod reviewing history. I review the very first 5GB model – what we’d now call the iPod Classic 1G – in The Age back in 2002. Back then the iPod was only Mac compatible, and since I was a Windows person, Apple supplied me with Mac for the purposes of the review. The next time I sought a review iPod, Apple kind of sniffily informed me that they only supplied iPods for standalone reviews, not comparisons of the kind I’d proposed (and which was how I’d conducted the earlier review). It was eight years before I was able to lay hands on any more Apple gear for review.

    Apple iPod Classic 4G screeen

    Ever since then I’ve assumed that it was an Apple policy regarding comparison reviews, but in view of some recent reading and the fact that I was again frozen out by Apple when I sought to review an iPod Touch three or four years ago on Australia’s leading tech review site, I’m starting to wonder if I’d managed to get myself on the reputed Apple blacklist. I had generally been ravingly positive about the unit – “Apple is a computer company and, as such, has no right to make an MP3 player as good as this one”. But I did note in that review that running into a 32-ohm load the bass was weak. Could that have gotten me on a blacklist. I’ll never know.

    Anyway, thank you Marek for the chance to at least partially fill in the gap.

    Listening with the iPod Classic 4G

    This article isn’t really about the listening experience, but of course I did plug in some headphones and run the music while doing other stuff. And, of course, I was frequently distracted from that other stuff by the music and the sound. I did not, and I stress did not, use any Apple earphones, and most especially not the kind of earbuds which would have been originally supplied with this iPod. Over the years I’ve tried them, and I’ve found them terrible on both a practical and sound-quality level. Perhaps they may have sounded okay could I have achieved a decent sound seal for my ears. But the hard Apple buds of those days insisted that your ears conform to their shape, rather than them conforming to your ears. They certainly never fitted my ears.

    So, the main set of headphones I used weren’t earphones at all, but proper high quality earphones. Indeed, I used full-sized Final Audio D8000 over-ear planar magnetic headphones (Final Audio D8000 review here). As I listened, I had not yet done any measurements. If there was any bass droop, it wasn’t apparent with these headphones. That droop tended to be for low impedance headphones, though, and these ones have a nominal 60 ohms and only modest variation from that across the full range of frequencies.

    Apple iPod Classic 4G

    As for overall sound, I had expected some sloppiness, lack of focus, and perhaps worse problems such as some crackling or other artefacts due to failing components. But I was wrong. The D8000 headphones are incredibly penetrating, and even though most of the music I listened to was in MP3 format for the obvious reason that you can’t fit much ALAC content on into 40GB of storage, the sound was really quite respectable.

    As I’m writing this bit, I have Alice Cooper’s Welcome to My Nightmare playing. As is appropriate for rock music, the bass is rather forward, but quite tight. A little too forward? The D8000 headphones are very generous with their bass performance, but I was leaning towards thinking that “quite tight” for the bass was a suitable equivocation. So I figured I’d better do a quick comparison. I pulled the headphone plug from the iPod and inserted it into a Topping A90 headphone amplifier which was being fed by a Topping D90SE DAC connected to a Mac Mini running JRiver Media Center 27 and fed the same MP3 encode (MP3 VBR at around 190kbps it turns out, which means it’s one I created using the high-quality LAME MP3 encoder) to the D8000 headphones. The sound jumped up a level, clearly, in a couple of ways. The sense of reality was instantly enhanced, and the bass … diminished.

    Diminished, but was actually “tight”, without any equivocation at all. So, why the change? I explored the iPod’s settings and found that the EQ setting was at “Bass Boost”. Oh. I switched that off. After a few moments of my ears adjusting to the new levels, the tonal balance was clearly more even and the bass was tighter, but … But, not as tight or controlled as I’d sensed with the Topping rig.

    Apple iPod Classic 4G

    Look, as a rule I’m reluctant to say that a particular piece of electronics (as opposed to loudspeakers or headphones, which are a very different proposition) sounds better than some other particular piece of electronics. But with the iPod Classic 4G, using the same headphones and the same VBR MP3 encode on the same pieces of music, it’s clear that modern high-quality DACs and desktop headphone amplifiers are substantially better than a 17-year-old iPod Classic. And it’s not just with the bass. Everything was much more controlled, focused, “present” with the modern gear than the iPod.

    And all that said, the iPod sound was far from objectionable. It smeared over detail and reality a little, but still presented enjoyable music. And given that most people back in the day would have been using Apple’s appalling earbuds, any very slight weaknesses in the electronics would have been undetectable.

    The main game: some measurements

    So, what do measurements of the fourth generation iPod reveal? I conducted two sets: first to measure frequency response, distortion and noise levels. Then to establish output levels into different loads.

    So, let’s start by looking at the frequency response. Back in 2002 I’d noted that the original iPod delivered effectively a ruler flat response into a high impedance load, but a response that drooped significantly in the bass into a 32-ohm load (-7.9dB at 20 hertz, -2.6dB at 50 hertz).

    These days I’m using more realistic impedance loads: 16 ohms and 300 ohms. Plus, of course, a high impedance load (set by my analogue to digital converter). Here’s the graph:

    Apple iPod Classic 4G frequency response

    It’s probably just as well that I’m not longer in the business of asking Apple for review products. As you can see, there’s a very slight droop at the bass end even into 295-ohm loads. Okay, it’s just 0.4dB at 20 hertz, but it suggests something. Into a 16-ohm load, things go a bit haywire, with the output down by 4.7dB at 50 hertz, and rapidly heading into oblivion. It looks to me that Apple may have maintained the same output stage into the fourth generation as it had in the first. That’s a stage that apparently has a protective capacitor in line with the output.

    Here are some of the other measurements in tabular form:

    Apple iPod Classic 4G measurement results

    The first column shows a direct connection from the iPad to my ADC, the other three are via my load impedance box. As you can seem noise is slightly less than -95dB in all conditions. With 16-bit audio, I get some devices that can manage into just under -98dB. But … if you can hear even the slightest hint of this noise, you’re better at it than me. This graph shows the actual noise floor:

    Apple iPod Classic 4G noise graph

    Back to the table. We can see THD increases a little into the 295-ohm load, and a lot into the 16-ohm load. Similarly, but less nastily, for IMD. Even crosstalk – leakage from left to right and from right to left – goes up a huge amount when the impedance is low. Why, it’s starting to get close to the separation levels available with vinyl LPs!

    I’m thinking that the 60 ohms of the Final Audio headphones is rather closer to the weak 16-ohm measurements than it is to the rather stronger 295-ohm measurements.

    So, what about output levels?

    Well, the iPod Classic 4G really doesn’t have much to be ashamed of here. First, I’d suggest never advancing above one click of the click wheel short of maximum. Full scale sine waves clip with that setting, even into a high impedance load.

    One click short of max was fine for high impedance loads, but further reductions were needed for lower impedance loads. I also had to pull back the output a further notch for the 10kHz test signal into 295-ohm loads, but that really doesn’t matter. In actual music, 10kHz content is never going to go within several orders of magnitude of challenging this level. So for all practical purposes, you can expect around 3.4mW of power into 295-ohm headphones, which equates to around 5.3dB above the sensitivity rating of the headphones.

    Apple iPod Classic 4G

    Into low impedance – 16-ohm – loads, things change quite a bit. You can get nearly 21mW in the middle frequencies – that’s 13dB above headphone sensitivity rating, but rather less at 14mW and 11.5dB due to that low frequency rolloff at 100 hertz. I expect it would be much, much lower at 50 hertz, and even lower at 20 hertz.

    Finally, the output impedance of this device seemed to be, in general, slightly less than seven ohms, exept for low frequencies into low impedances when it increased to around double that.


    The good news about the iPod Classic 4th Generation is that it demonstrates clearly that portable audio sound was pretty decent way back in 2004, but has noticeably, clearly, improved since then. I would be uncomfortable if you asked me to say whether a current model, high quality, portable digital audio player sounded better than, say, a current model, high quality, desktop audio system. In most cases I could not confidently tell them apart. With the iPod? Yes, there was a clear, audible difference.

    Finally, if you’re thinking of picking up an old iPod Classic, consider a 5th Generation model. I understand that the bass problems were fixed in that model.


    * Prior to the iPod’s ascent, the biggest-selling portable MP3 player supplier on the world market was South Korean firm IRIVER. In 2013 IRIVER redefined the portable digital audio player market by introducing the first of its Astell&Kern models, players which put audio quality first and which are generally regarded as true audiophile quality digital audio players.

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