The following information is from the "Guide to the Macintosh Family Hardware" available through Addison-Wesley dealers. This information applies to all models using the Apple Sound Chip.
"The external sound jack is at standard line level (approximately 1.5 volts peak-to-peak) and its source impedance is approximately 47 ohms. The jack is capable of driving a headphone load of 8 to 600 ohms, or the input to almost any audio amplifier or amplified speakers. It will not adequately drive a directly connected external speaker. The external sound jack is short-circuit protected."
Article Change History:
26 Apr 1995 - Revised format of article.
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