> I've been trying to find info on line and mic level signal > characteristics. > I checked ieee for an audio signal, computer io... standards and anything > else I thought would lead me to a definition of each and came up with > nothing.
_New Audio Cyclopedia_ ed. by Glen Ballou covers this in detail. Line levels are +4dBm, where the m stands for milliwatt. Therefore +4 levels are referenced using 600 ohm loads and .001watts. To figure voltage use: dB = 10log(v^2/600 / 0.001) dB is where you'd put the +4. Mic signals aren't so simple because, like acoustical sounds in the ambient, they cover wide ranges of power. But is +4 is your line level, and a typical mic preamp offers 40 to 60 dB of gain ... then you have your answer. Your scope and a suitable sound source and loaded microphone will show you what your peak levels will be. Maybe that would help. Phil _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user