

Audio engineering types the world over are devising ways to test the sound quality of Apple's new iPod Classic, because it's massive capacities (80GB or 160GB) and support for high-quality codecs (Apple Lossless, WAV, AIFF) make it the natural choice for people who are serious enough about audio quality to include their listening equipment in their signature files.

One of the most comprehensive tests was done by Marc Heijligers, a professional audio PhD. He admits his test was somewhat compromised by using a laptop input to record test signals from the iPods, but since he used the same input for both the 6G iPod Classic and the 5G/5.5G iPod and managed to turn up significant differences, the test appears to be valid. It paints the new iPod Classic as a possible downgrade in terms of sound quality – at least as far as golden-eared audiophiles are concerned (some of these people spend hundreds of dollars per speaker wire).

Images of cracked open iPod Classics reveal that it has a cleaner signal path from the digital-analog-converter (DAC)

chip to the line-out jack, so the problem, such as it is, appears to be with the Cirrus chip Appleused for the Classic as opposed to the Wolfson chip found in the5G/5.5G iPods.

Everyone's ears are different, but Heijligers' test found three problem areas:

- A slight uplift in treble [boosted high frequencies] - A group delay that depends on frequency [fuzzy 3D image] - A strong modulation with 22.1k, causing intermodulation distortion [distortion]

Depending on where the problem lies (assuming it's actually a problem – some people think the 6G iPod Classic sounds warmer and crisper), Apple might be able to fix it with a firmware upgrade. According to Heijlifers, version 1.0.1 of the firmware did not resolve the issue.

(image from