Just a few Questions

[anti-idiot]

Hi, i have this very odd schematic and i wanna know just 3 things. first, what the hell is this symbol?

L7


second, how much is the total resistance of the input, so i can calculate the total gain (just for the second op-amp)



i'm guessing, first, with the switch open, is:
Parallel R52 & R53,
Parallel R50 & R51, in series with R92
and both values in parallel, right?

third, wanna know the gain of the first and second amp (asuming pot is at max)

[anti-idiot]

ok, a friend told me L7 is some kind of dual inductor to supress RF frequencies.

now i have some questions bout how to calculate the gain of both second stages. any help? please?

[anti-idiot]

nobody?