Apple iMac - Manual (Page 37)

C H A P T E R 3
Devices and Ports
Sound System 37
■ during power cycling
External Sound Output 3
The external sound output jack is a 3.5-mm mini phone jack located in the I/O
bay on the right side of the computer. It accepts a stereo miniplug-to-RCA cable
adapter for connecting stereo equipment to the computer.
The sound output jack has the following electrical characteristics:
■ output impedance: nominal 180 ohms
■ maximum level: nominal 1 V rms (2.8 V peak-to-peak)
Headphone Jacks 3
Two headphone jacks are located on the front of the computer next to the right
speaker. Each sound output jack provides enough current to drive a pair of
low-impedance headphones.
The headphone jacks have the following electrical characteristics:
■ output impedance: nominal 13 ohms
■ maximum level: 1.4 V rms (4.0 V peak-to-peak)
Headphones should have an impedance not lower than the recommended
minimum impedance of 32 ohms. Headphones with lower impedance can be
used, but with some degradation in performance.
Sound Specifications 3
The frequency response of the sound circuits, not including the microphone and
speakers, is within plus or minus 1 dB from 4 Hz to 20 kHz.