microphone

[zesla]

Hi,

Is this sentence true?
"The output voltage on a dynamic microphone may be very low, typically in the 0 to 100 microvolt range. A microphone preamplifier increases that level by up to 70 dB, to approximately 0 to 10 volts"
Microphone preamplifier - Wikipedia, the free encyclopedia

My caculations just showed almost 0.3V for the 100uV. but the page tells 10volts!

by the way I thought that dynamic mikes do not need preamp's because they are robust than electret one's?

Thanks

 

[Dragon Tamer]

Every mic is different, the voltage typically depends on the resistor that you have before the mic. The larger the resistor, the lower the voltage. 300mV and 100uV is a significant difference, but they both still need a preamp. And dynamic mics should still have a preamp regardless of how robust it is. The preamp is increasing the signal level so that it can be heard easier. A preamp can be made using an array of transistors to boost the signal, or it can be an audio amplifier.

 

[audioguru]

A dynamic or an electret mic has an output of about 5mV to 10mV when it is 10cm away from your mouth and you are speaking in a normal conversational voice level. The level is in microvolts if the mic is far away from you and if you whisper. The level is 100m to 200mV if the mic is very close to you and you are screaming loudly.

70dB is 3200 times. So 100uV x 3200= 0.32V which is "line level".

 

[Dragon Tamer]

See, audioguru knows. Always best to get a second opinion.

 

[zesla]

A dynamic or an electret mic has an output of about 5mV to 10mV when it is 10cm away from your mouth and you are speaking in a normal conversational voice level. The level is in microvolts if the mic is far away from you and if you whisper. The level is 100m to 200mV if the mic is very close to you and you are screaming loudly.

70dB is 3200 times. So 100uV x 3200= 0.32V which is "line level".

Ok thank you very much audioguru,

But plaese tell me about the line level acceptable values? How much of gain or impedance (I do not know)
the input should have so that we could call it a line level?
And is it posiible to use One jack for bothe the MIke and the Line level?

Thanks

 

[audioguru]

Signals vary a lot. A line level signal can be weak or be strong. Usually its input is 10k to 100k ohms.
Since a mic needs a preamp and a line level signal does not then use separate jacks for them. Besides, an electret mic needs to be powered.