The best way to wire a Microphone on NI 6120 DAQ card and acquire data

[wmg025]

Hi Folks,

I would like to wire a Microphone in my DAQ card NI 6120 in order to acquire audio better then the USB audio adaptor because I need to have a very high data resolution to test what is bad and Good in my products. Anyone have the best practice or good ideas to do this and would like to share ?

Thanks in advanced,

[Bob_Schor]

You need to think about matching voltage ranges, matching impedances, and proper grounding.  You should (probably) use your A/D in differential mode.  You do know, don't you, that your A/D converter is only 16 bits, which may limit the resolution (in Y) of your input signal -- for audio, and particularly for "high data resolution", I think 24 bits is more often used.

Bob Schor

[joej]

It looks like the card has a range setting and sample rate that can accomodate an audio microphone  at +/- 200 mV.  What do you mean by "very high data resolution"?  That could be voltage resolution and as Bob pointed out, 16 bits of voltage resolution is at the low end for modern audio capability.  If you mean frequency resolution, certainly the sample rate capability of the 6120 bests the typical sample rate of a vanilla USB audio adapter, which would increase the frequency resolution at the highest audio frequencies.  

You'll need to say more about what kind of microphone it is and what kind of measurement you want to highly resolve - detect accurate frequency content, or a sound pressure dynamic, i.e. something going from really quiet to really loud.  Also many microphones these days I suspect are buffered, that is they have their own preamp built in and provide a single ended, ground referenced output - so that would need to be accomodated in how you setup the 6120 AIs.