After replacing the provided electret microphones, this kit works well. Easy build, plenty of gain - although, as above, the board's channel markings are reversed with conventional headphone plug wiring; otherwise, the board quality is fine.
The provided microphone elements are omnidirectional so there is little stereo sound field with only ~2" separation. More importantly, the supplied elements were excessively noisy with unbalanced frequency response and sensitivity; a bad batch, perhaps. I replaced them with a new pair of smaller elements I had on hand.
PRO: Very sensitive mics. Runs on 3 AAA or 1 9v. I am a BIW and I use this board in my helmet. I actually use 2 boards. One to drive my speech and the other to give me stereo hearing. It drives my headphones very well, I can't even use it on 1/2 power as it becomes too loud.
Con: L & R are reversed as connected to the headphone jack.
the solder lands and traces were very poor..even with a temp controled station,the free lands came completely off and stuck to the tip,the lands and traces came up off the board and cracked. the slightest finger pressure on the componet side would break the lands...I bought two of these and had to make multipal repairs on the circuit board side before they would even work ! the mic's were a pain in the butt to mount,and when it's all said and done the output levels are not balanced...I'm not very happy with these products.
For the price this mic is unbelievable. You can hear a whisper at over 100 ft and discern what is being said. It is so sensitive you have to be careful where you direct it because you hear your own breathing. A case would be nice but I think you could easily make one out of a covered soapdish if needed. It is very frugal when it comes to battery consumption. I've had mine on continuously for more than 6 hrs straight without depleting the 3 AAA batteries! Easy to build with basic soldering skills.
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MCM is a great company. Very fast service and shipping of Raspberry Pi. Will tell all my friends to buy from MCM