Electret microphone question

[zobsky]

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/c...tretinput.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 ?

[SY]

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.

[Juergen Knoop]

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

[zobsky]

Thanks to both the posters. Those were the answers I was looking for. I'll build a pre-amp.

[Juergen Knoop]

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

[zobsky]

Originally posted by juergenk
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

[Juergen Knoop]

the circuit is for interfacing a dynamic microphone faking it into a electret one.
it won't work with a electret capsule

[zobsky]

Originally posted by juergenk
the circuit is for interfacing a dynamic microphone faking it into a electret one.
it won't work with a electret capsule

That's true for for the first circuit on the page, .. not for the ones way down using a battery and a resistor & capacitor.

[SY]

Take a look at the Mighty Mike article that Joe d'Appolito wrote. It's a very simple circuit that works great.

[Juergen Knoop]

using a battery and a resistor & capacitor.

thats not needed with a mic-input
regards