Apple powermac g3 blue.white サービスマニュアル

 Basics

Sound - 36

  The Apple PlainTalk microphone requires power from 

the main computer, which it obtains by way of an extra-long, 

4-conductor plug that makes contact with a 5-volt pin inside 

the sound input jack.

The sound input jack has the following electrical 

characteristics: 

• input impedance: 20 kW 

• maximum input level without distortion: 2.5 V peak to 

peak (Vpp) maximum 

• line-level microphone voltage range of 0.28 V to 2.1 V 

peak to peak 

• input SNR <90 dB unweighted (typical) for recording to 

system hard disk drive or system main memory