Hi
The gain of your circuit, the part with the R, L and C, is as follows:
Amplitude=Vin*(w*L)/sqrt((R-w^2*C*L*R)^2+w^2*L^2)
where
w is the angular frequency equal to 2*pi*f where f is the frequency in Hertz, and
R is the series combination of R1 in the schematic and the mic resistance.
With an amplifier before and after this section, the amplitude is simply multiplied by the two gains, so if we have the first gain G1 and the second G2 we end up with:
Amplitude=G1*G2*Vin*(w*L)/sqrt((R-w^2*C*L*R)^2+w^2*L^2)
The two 3db down frequencies i had given previously, and the midband max occurs at 1/sqrt(LC) as previously given, so the peak midpand gain is:
Peak=G1*G2*Vin*1=G1*G2*Vin
This comes from evaluating the Amplitude with w=1/sqrt(LC).
However, the second amplifier appears to be an LM386, and the gain for that is set a little differently than for a regular op amp. You should look up the data sheet for the LM386 and find out how to set the gain for that section and also if it will change the frequency response a little bit. The first amplifier assuming it is a regular op amp looks correct.