iPod Audio performance

The third-generation iPod had a weak bass response, as shown in audio tests. The combination of the undersized DC-blocking capacitors and the typical low-impedance of most consumer headphones form a high-pass filter, which attenuates the low-frequency bass output. Similar capacitors were used in the fourth-generation iPods. The problem is reduced when using high-impedance headphones and is completely masked when driving high-impedance (line level) loads, such as an external headphone amplifier. The first-generation iPod Shuffle uses a dual-transistor output stage, rather than a single capacitor-coupled output, and does not exhibit reduced bass response for any load.

For all iPods released in 2006 and earlier, some equalizer (EQ) sound settings could "distort the [bass] sound far too easily, even on undemanding songs". This would happen for EQ settings like R&B, Rock, Acoustic, and Bass Booster, because the equalizer amplified the digital audio level beyond the software's limit, causing distortion (clipping) on bass instruments.
From the fifth-generation iPod on, Apple introduced a user-configurable volume limit in response to concerns about hearing loss. Users report that in the sixth-generation iPod, the maximum volume output level is limited to 100 dB in EU markets. Apple previously had to remove iPods from shelves in France for exceeding this legal limit.

Related articles :

• iPod
• iPod History and design
• iPod Trademark
• iPod Software
• iPod User interface
• iTunes Store
• iPod Games
• iPod File storage and transfer
• iPod Connectivity
• iPod Accessories
• iPod Patent disputes
• iPod Sales
• iPod Industry impact
• iPod Criticism

References :
wikipedia