The sound system sends computer-generated sounds to four destinations:
The iMac computer has a single internal speaker that operates when no external speakers are connected. The internal speaker uses a monaural mix of the left and right channels.
The Apple Speaker minijack is a 2.5-mm stereo minijack. It has a smaller diameter than the headphone jack so that the user cannot inadvertently plug typical headphones into it.
WARNINGMany cell phones, along with some types of headphones and other audio devices, have a 2.5-mm plug. The user must not plug such devices into the Apple speaker minijack. Doing so could cause damage to the devices.
The Apple Speakers include an internal ROM that enables the computer to identify the speakers. Speakers other than the Apple Speakers should not be connected to the Apple Speaker minijack.
The iMac has a 3.5 mm minijack for stereo sound output. The headphone jack is suitable for connecting a pair of headphones or amplified external speakers. When a plug is inserted into the headphone jack, the internal speaker and the Apple Speaker minijack are disconnected.
The sound output through the headphone jack has the following electrical characteristics: