The Power Mac G4 computer has one built-in speaker and a 3.5 mm mini jack for stereo sound output on the back of the enclosure. The output jack is suitable for connecting a pair of headphones or amplified external speakers. Inserting a plug into the sound output jack disconnects the internal speaker.
The sound output jack has the following electrical characteristics:
output sound signal-to-noise ratio (SNR) <90 dB unweighted (typical) when sound playback is from system hard disk drive or main memory
output sound SNR <80 dB unweighted (nominal) when playback is from CD
overall output sound SNR <90 dB unweighted (typical)