I used to put plain old low voltage rectifier diodes across the inputs of electronic crossovers I built decades ago. I used 4 diodes. That would clip any signal to ground over about 1.4vp. Any silicone diode in series like you plan on doing will not conduct until the output of the mic is about .7v (700mv). Does the mic have that much output? Why don't you you simply use the pad on the channel input of a mixer and adjust the eq?