Describing my outside microphone setup

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Uploaded by: radiorobbe

Upload date: 4/29/2025

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Hello folks! Steffen here, also known as Radiorobbe. 

Since some of you have been wondering how my 24/7 street microphones work, here is a brief explanation of my setup. It's not very professional, but it's working fine for more than 5 years. 
First of all, I apologize for the artificial version of my voice. It corresponds to my voice when I was about 10 years younger and was trained with some of my German podcasts from that time. I could try to stutter my way through the automatically translated text, but I'd rather not do that to anyone. Anyway, back to the topic.

First, the mics. These are two standard Primo omnidirectional electret capsules (EM272) attached to the outside window sill using simple metal clips. The capsules are available as ready-made microphones from various manufacturers for about $100, e.g. as Clippy EM272. These microphones have the advantage of being relatively discreet and can be used in almost any weather. Even if they get wet, they usually don't break easily. They do sound a little strange for a while, but once they dry out, they work fine again. Small fur windscreens are on top of the capsules. Unfortunately, they are not very effective, but at least they keep out small gusts of wind. The microphone cable is thin enough to go through the window frame without drilling. However, I put an extension cable between the mics and the sound card to avoid damaging the actual microphone cable when opening and closing the window. 

Now to the signal processing. The microphone is currently connected to a cheap USB sound card, model Axagon ADA-17. It costs just around $20 and is one of the few sound cards in this price range with a 3.5 millimeters stereo microphone input. An audio recorder with a USB interface or a mixer might be a better solution, but a test showed that the sound quality of the USB dongle is hardly worse than that of an Olympus recorder, for example. I also wanted to keep the technical effort to a minimum, as there is currently no room for an additional mixing console. The computer is a cheap Beelink S12 Pro Mini PC. These computers are very quiet and energy-efficient, making them ideal for such tasks. Of course, you can also use a Raspberry Pi for streaming, which I have done when first setting up the mics. However, since the computer has other tasks that have nothing to do with streaming, a better solution was needed. 

The rest is just software. The microphone signal is streamed to an Icecast server using the RadioCaster program. Then the non-public stream is archived in audio files of one hour each, allowing me to quickly cut out noise or special events from the stream, provided I know about them of course. Over the past 5 years, I have been able to collect a considerable number of odd and sometimes spectacular audio clips in this way. Lightning strikes, fighting cats, falling trees, and of course crazy people that I don't want to share with a wider audience for privacy reasons. In summary, I'd say that 95% of the time it's very boring, but for the remaining 5%, the technical effort was worth it. 

Well, that's all for now. I hope I've inspired some of you to try your hand at building such a system. If you want to build your own, you can expect to spend around $200 to $300, with the computer being the most expensive component. Hhave fun!

I'm impressed with the quality of the AI voice.

Thank you for doing this.

@ironcross32 Tanks. The voice has too much breath noise for my taste, but otherwise it is very close to my natural voice.

Awesome, thanks very much for the setup, I would love to try this, would need to do some changes though given that there is no room near the window for a computer, guess the old Olympus ls14 or lsp4 will do the job, cutting the files can be manually done :)

If you hadn't said, I wouldn't even have noticed your voice was artificially generated. It's miles better than the one I made with personal voice. Do you stream your 24/7 audio anywhere? I would actually listen to it for a few minutes now and again. It's intriguing listening to a live feed of some other part of the world.