Electret microphone question

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I should be getting my panasonic mic capsules today. Intended purpose is to measure loudspeaker response.

I need to wire up the mic capsule.

Option 1. Build a simple mic pre-amp to power the capsule (powered by battery)
Option 2. Use the 5V bias on my sound card for the same purpose

These options are described at the bottom of the page http://www.tkk.fi/Misc/Electronics/circuits/dynamic_to_electretinput.html

Questions:
1. How come I never see option 2 recommended for DIY audio purposes (although I guess cheap headset mics use exactly this method)?

2. For option 2, wouldn't I still need a DC blocking capsule inline with the mic capsule ?
 
Well, it's not like they've got a screamin' high output. Getting some voltage amplification and low source impedance locally makes the whole interfacing issue much easier. I used a single battery-powered opamp configured for 40dB of gain, and that gets the levels just right for the sound card I use.
 
you could connect the capsule without any interface to the mic input
sadly the soundcards mic-input has no flat frequency response
the picture shows my onboard cmedia-card. This one of the flatter frequency responses I have seen
my older computer had a really worse mic-input
regards
 

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juergenk said:
this is just something to be aware of
your soundcard may be fine

I'll try a loopback from sound card(Audigy 2) to mic input with TrueRTA. That should tell me.

Also, is there any disadvantage to the simple mic-preamp I linked to in my first post (apart from a possible issue driving long lengths of cable)? I only intend to use a meter or two for my application.

Thanks
 
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I'm just about to design a microphone pre-amplifier for exactly the same use as you. I'll be using an electret capsule where I assume that the source of the FET in the capsule is either already disconnected from the case, or can be disconnected from the case. Op-amps will not be involved. Yes, I will post the design if it works properly.
 
I'm also in the process of fiddling with an electret microphone.

I am trying to repair a shotgun mic that had a broken electret capsule. The microphone body itself doesn't seem to have another amplifier so the only amplifier in the whole unit is the FET built into the electret capsule.

I replaced the capsule and biased it using the circuit on the bottom of the page zobsky pointed out. I changed the 1K resistor to 2.2K because my electret capsule said its impedance was 2.2K.

Everything seems to work but the output of the mic is very low.

Not sure if an external amp was orignally needed because this mic seems to plug direclty into the xlr jack of my camcorder.

THanks
 
What exactly do you mean by without the extra circuitry?
Like directly hooking up the electret capsule (with the battery and biasing circuit) to the xlr jack?

I believe the microphone itself has some other circuitry inside, but i think its for the M and V switch which toggles a rolloff filter or something.
 
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