We would like to use the Audiomoth as a recording platform for adapting some ultrasound microphones to it (the Bufo or Myotis from our Sonitor system) to get low-noise recordings.
I would like to know whether in principle, it is possible to de-solder the built-in microphone (or install a switch, simply) to connect another microphone (like the Knowles SPU0410LR5H-QB or Vesper''s VM1000) to the PCB even though those microphones' native sensitivity would be much lower than the built-in microphone's, around -38 dB.
Are the pre-amps on the Audiomoth strong enough to boost the signal to an acceptable level? If it worked, we would be keen to show that the Audiomoth can be expanded with this open-source mic system. We would like to show that in an upcoming new version of our aforementioned article for which we would be glad to get new collaborators involved.
Hi, The next version of AudioMoth which we are working on now and will hopefully be out early next year will support external microphones. In principle you should be able to modify the PCB to accept any microphone. Alex
These are excellent news Alex, thanks! Could you disclose more information about what kind of interface (connector, solder pads) would be used?
Hi Alex, your post on twitter was really eye-catching. Do you have any news about the next Audiomoth with external microphone ?
https://twitter.com/OpenAcoustics/status/1185968565960220673
Hi, It will definitely be later this year. We have the case coming out next, and then an update to the firmware to support triggering. We're ordering the final PCB versions for the external microphone this week and will be testing it over the next couple of months. Alex
Hi Alex,
Thanks that is such good news! It also relates to one of my other posts where I asked about a triggering function, so that's also answered now.
Just a quick question, will the external mic be a specific Audiomoth microphone with a specific cable? Or will we have to use other types of microphones (if the Audiomoth only comes with an external mic port)?
Also, I need to monitor at heights of 100 - 120m for wind farms, will the hardware be able to support such long microphone cable extensions for me to have the actual Audiomoth device close to the ground?
As far as I know the higher frequency calls may suffer a bit at such long extensions.
Thank you very much for the help.
Hi there, congrats on rolling out Audiomoth 1.2 with connectivity to external microphones!
However, it is unspecified what kind of microphones could be connected to the Audiomoth with the 3.5mm audio jack. I suppose, only Electret-condensed mics that need a voltage bias? Probably not MEMS elements?
Hi Kevin, There‘s an application note coming out today to describe this. It is intended for Electret capsules. However, it would probably work with a MEMS microphone with the appropriate circuit. We’ll have a look at this option. Alex
Hi Alex, Did you finally have a look and how to use an external MEMS micro? I purchased a Knowles SPU0410LR5H-QB from Micbooster mounted in a PCB: https://micbooster.com/ultrasonic-microphones/146-ultrasonic-mic-board.html
and soldered in a mono jack wire, attaching the + and out (signal) to the tip and the - to the sleeve. But the AM does not get any audio (no sound, just noise).
Many thanks,
Rob
@Robert Manzano Hi Rob, It is possible but needs an additional circuit along with the MEMS microphone to make it look like a conventional electret microphone so this isn't very easy to do. Alex
Hi Kevin,
The application note is now available, check out our latest announcement with the link.
Andy
The note doesn't mention the PIP voltage value. Depending on the voltage supply of the PIP provided from the device, some electrets would work better than others.
Hello, I would like to know if tests have been carried out with primo EM272 capsules (new version of EM172)? The note "Using AudioMoth with External Electret Condenser Microphones ", only mentions the EM258 capsules. The latter displays an operating voltage of 3V against 5V for the EM272. Could an EM272 capsule still work? Thank you very much, Thomas Zgirski
Hey Thomas, not sure if they have done any testing with the EM272 or not. The primo mics are hard to source in the US and I found alternatives to the EM172. I have never come across a recording device that has 5 volt plug-in-power (which is the EM272 operating voltage-https://micbooster.com/datasheets/EM272.pdf). Most recorders with plug-in power output around 2-3 volts. That being said I have plugged a EM172 into a plug-in-power recorder and it worked but maybe not to its fullest potential. I prefer this mic element made by PUI Audio which is rated at 3 volts and has the same signal to noise ratio as the EM272 (https://www.puiaudio.com/media/SpecSheet/AOM-5024L-HD-R.pdf). This would also be more in line with the flu-in-power output capabilities. Hope this helps.
Thank you very much Hall for the response. I will order the latest version of the audiomoth and I will test with my microphones (EM172). I think it's worth it. My olympus LS11 and my sony PCM M10 give excellent results with the EM172. My idea is to be able to connect my parabolic dish to the Audiomoth to carry out night migration monitoring.
Thomas
Thomas, you should contact me on my email. I have been working on that same project for a couple of years and have some insight I could share. Halmitchell@gmail.com