Sound Inputs

The sound system accepts inputs from five possible sources:

• built-in microphone
• external stereo sound input jack
• sound from internal CD-RW drive
• call progress audio from the internal modem
• sound from USB audio devices

Built-in Microphone

The sound signal from the built-in microphone is sent directly to the codec circuits in the Screamer IC.

The nominal SNR of the internal microphone is 65 dB.

External Sound Input Jack

The external sound input jack is a 3.5-mm mini phone jack located on the I/O panel on the right side of the computer. The sound input jack accepts line-level stereo signals or an Apple PlainTalk microphone. It also accepts a stereo miniplug-to-RCA cable adapter for connecting stereo equipment to the computer.

The sound input jack has the following electrical characteristics:

• input impedance: nominal 2000 ohms
• maximum level: nominal 1 V rms (2.8 V peak-to-peak)