The Macintosh LC and Macintosh IIsi computers have built-in mono 8-bit
sound input circuitry. This hardware is supported by the System 7.0 Sound
Manager, which is included in System 6.0.7.
An electret microphone and a plastic holder to attach the microphone to the
front of a monitor are included with the system. The microphone has a male
miniature stereo phone connector. Customers can use any commercially available
microphone that does not require an external power source.
An attenuated RCA adapter cable, with a male miniature phone connector on one
end and two female RCA connectors on the other steps down the voltage level of
the incoming signal. Devices such as CD players or tape players provide line
out signals at a higher level than the 20 millivolt - 600-ohm impedance
expected by the sound input circuitry. If you use a non-attenuated RCA adaptor
cable in the audio-in jack, you will not hurt the system and it will still
digitize the signal, but it may be very distorted.
If you use an attenuated RCA adapter cable as an audio-out cable, it may
or may not work, depending on what you're connecting to. A standard RCA
adapter cable is recommended for audio out. If the microphone is plugged
into the audio-out jack, no sound will come out of the jack or the
internal speaker.
Both Sony and Radio Shack sell attenuated RCA cables. The Sony part number
is RK-G128 and the Radio Shack part number is 42-2461-A.
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