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Why not keep all the electronics and sound card in the house and run a long XLR cable to the microphone? Battery and sound card and preamplifier outdoors to th

Why not keep all the electronics and sound card in the house and run a long XLR cable to the microphone? Battery and sound card and preamplifier outdoors to then run a USB cable out to it seems like a bit of a faff.

kazinator 2y ago
I suspect that though the author describes running a USB cable to the house, he may be preparing it for remote operation. (If you can count on it being next to a house where you can run a USB cable, you could also just power it off USB and skip the battery, right? So the battery must be designed in for a reason.) The mic is a condenser mic, so a pre-amp is needed, XLR or not. Cheap mics tend to be single-ended things without the balancing transformer or amplifier, so that would all be extra cost. XLR connectors and cables are more expensive. You'd want to go into some audio interface with XLR jacks which is also more expensive.
- gwern 2y ago
  'remote' also means you can set up networks of them to cover your area. Just dump a bucket every n meters, and spend a few hours driving around every few weeks to harvest the data & swap out batteries.
hcfman 2y ago
I developed a recorder project last year that make's this easier and you could deploy it on a Raspberry Pi zero and use a wifi link. https://github.com/hcfman/sbts-aru https://github.com/hcfman/sbts-aru It's using a cheap (0.40c) sound card, but personally I choose to have high quality mics (primo em272 mic capsules, used in high quality parabolic systems. However, there's nothing to stop you using < 10.00 euro microphones.
- hcfman 2y ago
  Checkout how good the primo mics are here for example: https://acousticnature.com/journal/how-to-make-diy-microphone-with-em172-272-capsules https://acousticnature.com/journal/how-to-make-diy-microphon...
- hcfman 2y ago
  sbts-aru writes the files to an SD card so you don't need a whole running windows for this. Also, it passes all the audio through real time jackd, so while it's writing files you can also have an addition consumer running a real time matchin algorithm on it. If you use a Pi 4 or 5 you would be able to also do that at the same time on the same Pi as is recording.
pvaldes 2y ago
Or even better do it an isolated area to filter as much noise as possible
contingencies 2y ago
PoE works better (cheaper, higher bandwidth, differential signalling for higher EMI resistance, readily shared, etc.). Plastic covers are ~free (splash out and deploy duct tape if necessary). MEMS mic -> I2C -> cheap MCU -> ethernet. Theory: Capture digitally, and send the data - forget XLR and other expensive analog 'professional' fancabulation[0]. [0] https://www.youtube.com/watch?v=Ac7G7xOG2Ag https://www.youtube.com/watch?v=Ac7G7xOG2Ag
- jononor 2y ago
  I think you mean I2S (or PDM)? I2C is not common on MEMS microphones, as the bandwidth is generally insufficient for audio signals.
  - contingencies 2y ago
    Right, I don't usually touch audio or video applications.
- hcfman 2y ago
  POE very easily tends to inject noise into microphone inputs. If you run a Raspberry Pi for example with POE you get that. This can be fixed by using a power conditioning hat and a POE splitter but now the costs are really increasing. But it works.
  - 15155 2y ago
    Galvanically isolate the ~100mA of supply current you need - the Ethernet interface is already isolated.
    - hcfman 2y ago
      I’m pretty sure that Raspberry pi’s draw more than that. But if you have a good way to fix this I’d like to know. The pi supply hat also has that probably and no one has fixed it in a couple of years.

kazinator 2y ago

I suspect that though the author describes running a USB cable to the house, he may be preparing it for remote operation. (If you can count on it being next to a house where you can run a USB cable, you could also just power it off USB and skip the battery, right? So the battery must be designed in for a reason.) The mic is a condenser mic, so a pre-amp is needed, XLR or not. Cheap mics tend to be single-ended things without the balancing transformer or amplifier, so that would all be extra cost. XLR connectors and cables are more expensive. You'd want to go into some audio interface with XLR jacks which is also more expensive.

gwern 2y ago
'remote' also means you can set up networks of them to cover your area. Just dump a bucket every n meters, and spend a few hours driving around every few weeks to harvest the data & swap out batteries.

hcfman 2y ago

I developed a recorder project last year that make's this easier and you could deploy it on a Raspberry Pi zero and use a wifi link. https://github.com/hcfman/sbts-aru https://github.com/hcfman/sbts-aru It's using a cheap (0.40c) sound card, but personally I choose to have high quality mics (primo em272 mic capsules, used in high quality parabolic systems. However, there's nothing to stop you using < 10.00 euro microphones.

hcfman 2y ago
Checkout how good the primo mics are here for example: https://acousticnature.com/journal/how-to-make-diy-microphone-with-em172-272-capsules https://acousticnature.com/journal/how-to-make-diy-microphon...
hcfman 2y ago
sbts-aru writes the files to an SD card so you don't need a whole running windows for this. Also, it passes all the audio through real time jackd, so while it's writing files you can also have an addition consumer running a real time matchin algorithm on it. If you use a Pi 4 or 5 you would be able to also do that at the same time on the same Pi as is recording.

pvaldes 2y ago

Or even better do it an isolated area to filter as much noise as possible

contingencies 2y ago

PoE works better (cheaper, higher bandwidth, differential signalling for higher EMI resistance, readily shared, etc.). Plastic covers are ~free (splash out and deploy duct tape if necessary). MEMS mic -> I2C -> cheap MCU -> ethernet. Theory: Capture digitally, and send the data - forget XLR and other expensive analog 'professional' fancabulation[0]. [0] https://www.youtube.com/watch?v=Ac7G7xOG2Ag https://www.youtube.com/watch?v=Ac7G7xOG2Ag

jononor 2y ago
I think you mean I2S (or PDM)? I2C is not common on MEMS microphones, as the bandwidth is generally insufficient for audio signals.
- contingencies 2y ago
  Right, I don't usually touch audio or video applications.
hcfman 2y ago
POE very easily tends to inject noise into microphone inputs. If you run a Raspberry Pi for example with POE you get that. This can be fixed by using a power conditioning hat and a POE splitter but now the costs are really increasing. But it works.
- 15155 2y ago
  Galvanically isolate the ~100mA of supply current you need - the Ethernet interface is already isolated.
  - hcfman 2y ago
    I’m pretty sure that Raspberry pi’s draw more than that. But if you have a good way to fix this I’d like to know. The pi supply hat also has that probably and no one has fixed it in a couple of years.