Using a "real" microphone?

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bird_furniture

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Hi all,

I'm working on a project which needs a microphone input. For prototyping, the tiny electret condenser that's recommended for Teensy worked fine, but now I need something with higher audio quality, better rejection, etc. I'm using Teensy 4.0 with the Audio Shield.

I'm fully prepared to cannibalize a "real" microphone, and it seems like my options are as follows:

- use an analog mic, then use an amplifier to bring it up to line level for Teensy's line in
- use an analog mic, then use an ADC to translate it for i2s input
- use a digital/USB mic, and somehow feed that into i2s

Would anyone be able to point me in the right direction here? Surely I'm not the first to need a beefier microphone with Teensy, but I'm having trouble finding other threads on the topic. Any suggestions would be much appreciated!
 
i think the easiest/cheapest/most convenient solution is also the most common signal chain in professional audio surroundings - get a preamp to push the mic output to line signal levels, your first option. make sure you pick a microphone that does not need 48v phantom power, ie. use a dynamic microphone.

there are plenty of very cheap mic preamping circuits out there, so that shouldn't be an issue. for example the famous 5$ mic preamp.

of course your second option works as well, but depening on the ADC you might still need pre-amping/attenuation to get the mic output in the right voltage range.
third option sounds like an ugly bandaid workaround to me.
 
Thank you! This is very helpful. I will look into that $5 preamp, seems like the way to go. I'm glad not to have to resort to that third option...

Thanks again!
 
Been reading this thread, since I also plan to hook up a handheld dynamic mic (eg.Shure SM58 or similar).
Why couldn't I just use the mic input on the audio board to connect it to?
 
The mic input on the teensy audio shield is designed to allow easy use of common electret condenser capsules.
 
FEC8F658-45BD-4A3F-B5D6-B5BB7653742D.jpg

The mic input on the audio shield isn't just an audio input, there's a biasing source.
 
alex_vy said:
Been reading this thread, since I also plan to hook up a handheld dynamic mic (eg.Shure SM58 or similar).
Why couldn't I just use the mic input on the audio board to connect it to?
Click to expand...

Definitely rather noisy, dynamic mics are low impedance and a good mic preamp is needed to get a good
noise figure - otherwise there's little point moving to a professional microphone in the first place. And without
a differential input the EMI/hum pickup would be an issue.
 
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