# How do I find microphone output voltage?

Discussion in 'Electronic Basics' started by [email protected], Mar 8, 2007.

1. ### Guest

Hello,

How can I calculate the output level of a microphone,
I assume it is found from the Sensitivity , but how?
For example, I want to know what voltage I will
get if the SPL is 60dBA (on the sound level meter)

For example, I find in the datasheet Sensitivity = -40dB
Assuming this is actually dBV, then it should be 10mV
(1Volt/100), but at what SPL is that taken?

Mic.

2. ### Guest

The mic preamps I've used in the past with dynamics, electrets and
condensers ran 40 - 60 dB of gain. With my AKG C451s 46 dB is a good
level that covers the bulk of uage with no fiddling around. I know you
want to calculate the actual value but you just KNOW as soon as you
get it working you'll adjust the level anyway.

GG

3. ### Phil AllisonGuest

** The data sheet should tell you - but the usual reference
pressure level these days is 10 microbars ( ub) or
1 Pascal(Pa) .

A "microbar " is one millionth of atmospheric pressure and
equates to 74 dB SPL.

So, 10 ub = 94 dB SPL.

........ Phil

4. ### EeyoreGuest

A proper sensitivity spec will state the measurement SPL ( usually in
microbars).

What is it more generally you're concerned about ?

Graham

5. ### EeyoreGuest

Decent mic preamps have adjustable gain. It's essential when working with stuff
from close miking to recording wildlife.

80dB of gain range is not unknown and 50dB is routine.

Graham

6. ### Guest

So if an electret mic is quoted as Sensitivity = -60dB
then this means at 74dBA I will measure 1mV and at
134dBA I will measure 1V ?

7. ### Phil AllisonGuest

** No.

The reference SPL level is 94 dB in most cases these days.

134 dB SPL may well be beyond the ability of a budget electret mic.

......... Phil