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I'm working on a black-box piece of electronics which has a cylindrical "condenser microphone" with a main body diameter of 4 mm and height of 1.5 mm

I want to replace the condenser mic (black box) with a MEMS mic without redesigning the board.

Does anyone have a guess for the mic impedance (capacitive for a condenser mic) and/or volume-to-voltage-curve of similarly sized components? Any way to verify this with just a multimeter?

Is there any MEMS mic of good quality that has a form factor that could be a drop-in replacement for a cylindrical mic that's 4 mm diameter x 1.5 mm height, plus pins? I imagine the MEMS mic would thus either need to be passive (unlike most MEMS mics which are powered), or would need to have a jumper wire go to it from a power rail.

Thanks! Beginner here working on a black box system so I hope I'm asking the right questions.

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    \$\begingroup\$ No, I don't believe there are MEMS mics that are drop-in replacements for condenser microphones. The dynamics are different, for one thing, as also the power sourcing which you mention. \$\endgroup\$ – Anindo Ghosh Apr 16 '13 at 9:10
  • \$\begingroup\$ Anindo do you at least recommend some good microphone vendors who would have similarly-sized but higher-quality condenser mics so I can at least upgrade the mic while sticking to the condenser kind? Thanks! \$\endgroup\$ – AlcubierreDrive Apr 16 '13 at 9:12
  • \$\begingroup\$ Digikey and Octopart are my usual search starting points, then the respective manufacturer pages for additional research, and finally blogs and forums discussing any of the specific parts I've narrowed down to. That way I can start with a practical idea of price and availability. \$\endgroup\$ – Anindo Ghosh Apr 16 '13 at 9:13
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    \$\begingroup\$ From the description, your Condenser Mic is probably actually a electret mic (which is technically a type of condenser mic). Electret mics have some active components internally, and as such have a bias-network on the power connections. There may be even more to the conversion then properly powering the MEMS mic, you may need to figure out how to remove the bias used to power the electret mic. \$\endgroup\$ – Connor Wolf Apr 16 '13 at 9:29
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    \$\begingroup\$ Really, why are you trying to convert microphone types anyways? Electret condenser microphones can have excellent performance, and are widely available. The principle advantage that the MEMS devices have is they can be smaller. That's about it. \$\endgroup\$ – Connor Wolf Apr 16 '13 at 9:30
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I work for Analog Devices, who makes MEMS microphones. I have written an application note to describe how to use a MEMS microphone in a circuit that was originally designed to use electret mics. Along with the MEMS mic, it requires a few additional passive components to remove the bias from the signal and provide a dc supply to the mic's Vdd pin. https://www.invensense.com/wp-content/uploads/2015/02/Using-a-MEMS-Microphone-in-a-2-Wire-Microphone-Circuit.pdf. I hope this is helpful.

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    \$\begingroup\$ Wow, this appnote is the most incredible answer someone could have given! Thanks for the great guide on drop-in-replacing an electret mic with a MEMS mic. :) And Analog Devices mics are great. \$\endgroup\$ – AlcubierreDrive Apr 23 '13 at 3:48
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    \$\begingroup\$ Great, glad I could help. Good luck with your design. \$\endgroup\$ – Jerad Apr 23 '13 at 19:50
  • \$\begingroup\$ Thanks for the tip. I replaced a defective/noisy MEMS with condenser mic, an extra 4.7 kOhms resistor added between Vdd and OUT. Works fine. \$\endgroup\$ – ovidiu grama Apr 4 at 18:37

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