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The 16-bit stereo audio circuitry provides sound output through the built-in speaker and the headphone jack.
IMPORTANT
The iBook does not have a microphone or sound input jack.
The sound system is implemented by a Micronas-Intermetall DAC3550A stereo digital-to-analog converter. It contains an output analog source selector, analog gain adjuster, and output amplifiers that system software configures as headphone drivers or internal speaker drivers. The sound system supports a sample rate of 44.1 kHz and sample sizes up to 16 bits.
The frequency response of the sound circuits, not including the speaker, has minus 3 dB points of 20 Hz and 20 kHz. Total harmonic distortion and noise is less than 0.03 percent. The signal-to-noise ratio (SNR) is 90 dB or better, with no audible discrete tones.
The headphone jack is located on the left side of the computer at the left palm rest. The headphone jack is configured to drive a pair of low-impedance stereo headphones. External powered speakers may also be connected to the headphone jack.
The headphone jack has the following electrical characteristics:
The computer has one speaker located between the keyboard and the display. The computer turns off the sound signal to the speaker when headphones are connected to the headphone jack.
The sound system receives call progress audio from the internal modem so the user can hear the status of a dial-up modem connection. The level of the call progress audio is fixed.
Digital audio signals from the CD-ROM drive are sent to the Key Largo IC, which directs them through its I2 S interface to the DAC3550A sound IC. The digital audio is converted to analog by the sound IC and sent to the speaker and the headphone jack.