Can anyone point me to a table or chart that outlines the electrical characteristics of various audio signals, i.e. microphone level, phono (turntable), musical instrument (e.g. electric guitar), line level, headphone, etc.?
I’ve been working in audio-visual production for more than 30 years, and have a practical understanding of the differences, but when a friend asked for the technical details, I came up empty. I know that mike, phono, and instrument signals are “lower” than line level, but I don’t know how that translates into volts, watts, ohms, etc.
Can’t find a chart, but from old memory Line Level video or audio is 1V P-P, Cermaic phono is 100mv P-P, magnetic cartridge is somewhere around 2mv P-P. Microphone’s vary widely, a typical dynamic microphone is 1mv P-P Cermaic one’s are closer to 100mV P-P.
Usually moving coil microphones produce signals at around -80dBm(0.001V) this is often called phono level, however electrostatics mikes and those mikes with impedance changing amplifiers and transformers can churn out around -40 dB.
Turntables can also be divided in this way, however there is also the RIAA equalisation to take into account too.
There are two standards for line level, the most common is -10dB(or around 0.7V) for general consumers applications, but for serious studio work this is sometimes around +4dB(1.5V)
There are differant units or standards used, so that you get dBm - dB referanced to milliwatts to a specified terminated load.
Another is the more recent dBu dB refereanced to an unterminated load - this standard allows for greater headroom and is really more about digital audio signals.
This then leads to the problem of trying to equate one standard to another, the dBu is notionally referanced to a very high load impedance.