For future experimentation. There is an interesting comment here regarding wiring elecrets in parallel for better noise reduction and signal gain:

https://electronics.stackexchange.com/questions/324450/can-i-connect-multiple-electret-microphones-for-better-gain

"

You can increase sensitivity, gain, and signal to noise ratio by running multiple electrets in PARALLEL-not series. This works because:

1) each capsule has an onboard JFET. When combining noise from multiple FETs, some of it cancels. Two amps= -3dB, four amps= -6dB of noise reduction [see Small Signal Audio Design by Douglas Self, Routledge 2010].
2) Multiple elements will have lower output impedance, which can mean less noisy makeup gain down the line.
3) More diaphragm area means more sensitivity, which makes sense. It also means less self noise, for reasons that I don't really understand - but that's the principle behind the $3500 Audio Technica AT5047 (FOUR diaphragms!).

If you end up with a signal that is too hot and distorts the next stage, put a 10ohm resistor on the audio output of each capsule before wiring them in parallel. This averages rather than sums the outputs.

" 

On Monday, 23 August 2021, 16:26:05 GMT+1, aid <oootini@yahoo.com> wrote:


Thanks Grant. I'll respond on the thread if I figure anything out. 

Aidan

On Monday, 23 August 2021, 16:10:58 GMT+1, Grant Smith <grant@soundtent.org> wrote:


Hi Aidan

Thanks for the update.

Udo could be right on the mics, but I've found the Primo EM272s work fine with the iq card, and it seems the stream has sometimes been running well.

On possible noise from the 4G, I find that taking the dongle out of the box using eg a 1.5m male < > female USB extender usually resolves interference issues, and may take advantage of a better signal higher up.

I'm sorry that I can't offer a useful interpretation of the log. Maybe somebody else can. If the Pi can't access the device and there is no evidence of damage to the hardware, maybe it is a good idea to re-install the software.

Good luck with troubleshooting

bw
grant



On 22 Aug 2021, at 22:39, aid <oootini@yahoo.com> wrote:

Hi Grant,

I see the following error in journalctl: 

"
[locusonus@sherkin-streambox ~]$ journalctl | grep error
Aug 22 22:07:42 sherkin-streambox alsactl[227]: alsa-lib main.c:1405:(snd_use_case_mgr_open) error: failed to import hw:0 use case configuration -2
Aug 22 22:07:54 sherkin-streambox audio.sh[317]: alsa-lib main.c:1405:(snd_use_case_mgr_open) error: failed to import hw:1 use case configuration -2

"

The install is a rpi zero, iquadio soundcard, over a huawei 3372 4g dongle. The noise is intermittent, and is much louder at night. At this point, I'm very much out of ideas as to how to handle this, or whether anything can be done. I suspect that there is EMI from the dongle. Annoyingly, I had the set up running for weeks in my backgarden with no issues. The streambox is installed on an island, so maybe the 4g signal is weaker there. Maybe the iqAudio + rPi isn't such a good combination if it results in such noise in the field? 

Aidan

On Friday, 20 August 2021, 12:02:12 GMT+1, Grant Smith <grant@soundtent.org> wrote:


Hi Aidan

Thanks very much for the new streaming project and letting us know.

Listening in now I hear a lot of electronic noise, as you say.

Can you give more details on the installation / streambox, and I'm sure we can troubleshoot

bw
grant


On 18 Aug 2021, at 08:45, aid <oootini@yahoo.com> wrote:

Hi, I have installed a streambox on Sherkin Island off the coast of Cork, Ireland. When I installed it, it was very windy, and I didn't get to do a proper sound check in situ. 

Stream is here: http://locus.creacast.com:9001/sherkin_north_shore.mp3 There is some quiet digital noise in the background. the streambox is mounted distant from the mics. I have SSH access. is there anything I can tweak remotely to address this noise?

Thanks!

Aidan
_______________________________________________
Locustream / Locus Sonus Streaming Project http://locusonus.org/
To unsubscribe, send a message to locustream-request@nujus.net with unsubscribe in the subject
or follow instructions here https://nujus.net/cgi-bin/mailman/options/locustream
_______________________________________________