DIYbanter - View Single Post - Reducing hiss by changing op-amps ?

wrote:

I doubt it'll overload the PA head's mic amp if you substitute 3k3
for the 10k above.

I'm somewhat confused here... if I use 10K and 100R then I am going to
get 10mV (max) output for a 1V max input. If I use 3K3 then the output
will be 29mV. In both cases, surely this will overdrive the PA mic
input, which is expecting just 3.7mV max ???

I don't know where you got the 3.7mV max info. Sounds wrong to me.

You may be interested to know that a low impedance mic can easily produce
up to 1 *Volt* of signal when used close up and loud !

I recently designed a new unit with a fixed gain mic input and we allowed
for an input signal of up to 200mV as a reasonable compromise between
sensitivity and likely overload in its intended useage..

Graham