discussion / Acoustics  / 4 June 2019

Raspberry Pi Hardware Mono Mic Problem

Hi all,

I'm building a passive bioacoustic device for a PhD project and I have come across an issue for which I need advice from someone with more audio tech experience. 

I am in the final stages of preliminary device design, but I cannot find any hardware which allows me to attach a mono microphone with 3.5mm jack to a raspberry Pi 3 (likely the B+). I am aware of the Wolfson sound card and the Cirrus Logic card, but these are both either really hard to find or discontinued. I have spent a few hours looking through all the 'HIFI' 'DAC' 'HAT' products on electronic component sites to see if any offer a high quality mono mic input, but they all seem to geared towards high quality output for music playback. With my currently limited audio recording hardware knowledge, I am led to believe I require a mic input and line-in or RCA inputs will not work? I believe this has something to do with mic inputs being built in order to maximize quality of transmission, as opposed to line-in? And that RCA inputs are incompatible with mono?

As a recap, the situation is; a Raspberry Pi 3 (e.g. B+), a Clippy Mono EM172 microphone with 3.5mm jack, which needs a HAT or other hardware option to facilitate high quality recording between the microphone and the Pi. The purpose is for high quality recording of bird calls, so a built-in microphone does not replace the need for a directional high quality mono microphone to my knowledge. 

Thank you all in advance for your time and advice.

- Sam

Edit: I have realised that it may also be possible to use the stereo version of the Clippy microphone, but it is double the cost and I'm not sure it would be worth it if there is a more cost effective solution. In this case however, would a simple adapter such as the Behringer Audio Interface (made for musicians) or a HIFI DAC hat which offers a stereo attachment (HIFIberry DAC light) be the correct way to allow transmission of high quality audio to record?




Sam,

I suggest you look for a "USB Sound Card".  They  are small dongles that plug into one of the USB ports of the Pi and have a stero mic input that should accept your microphone plug, e.g.

https://www.newegg.com/global/uk-en/creative-sound-blaster-play-3/p/N82E16829102100?Description=usb%20sound%20card&cm_re=usb_sound_card-_-29-102-100-_-Product
that's just one example but a search with Google or on Amazon will give you plenty to choose from.

I'm not familiar with the Clippy microphone, but if it's this one:
https://micbooster.com/primo-microphone-capsules/65-clippy-em172-microphone.html

the spec says it has a stero 3.5 mm jack fitted, so you don't really want to be plugging that into a mono 3.5mm socket.

Good luck
EAP

We've had good results with two mono inputs accepted via the stereo 1/4" input jack on the Pisound HAT on a 3B+ and just about to test with the 4. Details and links to Pisound folks in Lithuania here -- http://www.orcasound.net/2018/04/27/orcasounds-new-live-audio-solution-from-hydrophone-to-headphone-with-a-raspberry-pi-computer-and-hls-dash-streaming-software/