For a school project we are working on building a karaoke machine. We have to build a circuit based off the specifications I have listed below. What I have a question on is what is the nominal line constraint mean. If someone could explain this to me in simple terms, so that i can understand what it means, and what it is going to tell me about the circuit I am going to have to build.

Equalizer Filter Center Frequencies: 50 Hz, 200 Hz, 800 Hz, 3.2 kHz, 12.8 kHz
Equalizer Filter Bandwidth (BW): 2 octaves
Input Signal: nominal "line" level (-10 dBv)
Output Signal: nominal "line" level (-10 dBv)

 

Try this article - http://en.wikipedia.org/wiki/Line_level

Since the output level is the same as the input, the circuit needs to have a gain of 1.