Mic Impedance

A

anywhither

Member
can anyone tell me how I can find out the Impedance of a mic?
just read something about matching Mic and Mic Pre.
but I still don't understand about the Impedance.
will a mic or micpre be damaged when they are not in same Impedance?
and how can I find a match set?
Thanks!
 
anywhither said:
can anyone tell me how I can find out the Impedance of a mic?
just read something about matching Mic and Mic Pre.
but I still don't understand about the Impedance.
will a mic or micpre be damaged when they are not in same Impedance?
and how can I find a match set?
Thanks!
Click to expand...

The concept of matching impedances shouldn't be applied to microphones, matching impedance is for transfer of maximum *power*. Since a microphone puts out a minute amount of power we are more interested in *voltage*. We want to transfer a large amount of the voltage from the source (mic) to the load (preamp).

The impedances of the mic and preamp act as a voltage divider so if the mic pre was 'matched' to the mic we'd be losing half the voltage. The solution is to have the mic preamp input impedance significantly higher than the impedance of the mic.

It should be noted though that too high an input impedance brings other factors into play like cable capacitance, where the cable starts to adversely filter the signal. Raising the input impedance has diminishing returns anyway

eg. 200R mic - 600R pre = 75% voltage at pre
200R mic - 1K pre = 83% voltage at pre

Search google for balanced audio etc. for more detail
 
No, nothing will be damaged if they are 'mis-matched'. Mic preamps are made to accept mic signals. What you are reading about is the effect that changing the imedance of a pre has on the sound of a mic. Recently, there have been pre's marketed that allow you to change the impedance, and thus the sound of the mic. It isn't matching in the sence that the input impedance is the same and the output of the mic. It is more about choosing the setting that sounds the best in your situation.

Unless you have a Viper or a Tampa, don't worry about it. You don't have a choice anyway.
 
anywhither said:
can anyone tell me how I can find out the Impedance of a mic?
just read something about matching Mic and Mic Pre.
but I still don't understand about the Impedance.
will a mic or micpre be damaged when they are not in same Impedance?
and how can I find a match set?
Thanks!
Click to expand...

The output impedance is usually in the literature that comes with the mic.

Most people consider an input impedance of about 10X the output impedance to be ideal. This is called "bridging". When people speak of matching mic to pre, they are talking about bridging the input. Most modern condenser and dynamic mics are around 150-200 ohms output impedance. Most modern mic pres are around 1500-2500 ohms input impedance. For the most part you don't have to worry about it anymore, at least with mics and pres.
 
You must log in or register to reply here.
Back
Top