Background noise (1 Viewer)

[Avetarda]

I´m attaching a recording of an eagle owl in which a little noise can be heard in the background (sounds like a "ffffffffff").
I use a Olympus LS P4 and a external mic ME66/k6, cable KA 600 and I´m very happy with the recordings, but...that noise...
Configuration: Nivel rec- medium.

Is this noise of Olympus pre-amps? Any solution? (Yes, you must buy a better recorder )

 

[tconzemi]

I don't get the feeling of a technical issue but more of natural background noise.
Are there any farms or large bird gatherings nearby (like cranes)?
Did you filter the very low frequencies (just below the Eagle Owl) with any software?
Pretty nice recording anyway, your Eagle Owls must be very actif right now, the male Eagle Owls at my place are calling, but still no female is answering at the moment.

 

[Avetarda]

The recording is original, without further editing than "fade", no filters. The recording area is quiet, a few kilometers away from roads and industries, although there can always be some background noise (cranes on roost).
The great owls now are on fire! 😍

 

[besaide]

Hello,

First post in this forum I am writting from Bizkaia (northern Spain)

I use the Olympus LS P1 with PUI AOM 5024L HD microphones:

https://www.puiaudio.com/products/AOM-5024L-HD-R

I use a home made version of an electret battery box:

https://www.making-sound.co.uk/projects/electret-battery-box.html

I'm attaching an example of this configuration (Little owl), no edits. Manual mode (gain level 10).

I would recommend using the manual mode with the olympus with a gain between 6 and 10 and the battery box I mentioned previously, works pretty well.

I bought a Tascam DR-100MKIII.... with the PUI AOM 5024L HD microphones did not get any significant improvements so I returned it. When I want quality, I use a home made parabolic + the home made battery box.

Some DIY proyects I am doing (spanish): https://paseandoconprismaticos.blogspot.com/p/diy.html

 

[Avetarda]

Sounds great the little owl! I`ll try to lower the gain in manual mode, I hope the bird isn´t heard too low later. The battery box ... that's for skilled hands . Thank you.

 

[besaide]

I do not use more than gain 10. If the sound is low then try with a home made parabolic dish with an umbrella (diameter 50cm) or try to get close to the bird.

I am attaching 2 examples so you can have an idea of the quality:

1 - A great tit with the olympus LSP1 + PUI AOM 5024 HD L external microphone + home made battery box (8.4v). No edits at all. GAIN level 6.

2 - A winter wren with the olympus LSP1 + PUI AOM 5024 HD L external microphone + home made parabolic dish (50cm umbrella) + home made battery box (8.4v). No edits at all. GAIN level 8.

 

[tconzemi]

I do not use more than gain 10. If the sound is low then try with a home made parabolic dish with an umbrella (diameter 50cm) or try to get close to the bird.

Do you have experience with parabolic dish in very deep sounds as male Eagle Owl?

 

[besaide]

Do you have experience with parabolic dish in very deep sounds as male Eagle Owl?

I have very very little experience. Mainly with Tawny owls which are very commun in my area.

I started birding a year and a half ago and with audio about half a year ago. All self-taught and learning as much as I can

I am attaching an heavily edited audio of what I think is an eagle owl, but it is an identification that raises doubts in my mind because it is not a common bird in my area.

 

[tconzemi]

I am attaching an heavily edited audio of what I think is an eagle owl, but it is an identification that raises doubts in my mind because it is not a common bird in my area.

I agree with Eagle Owl

 

[Avetarda]

Thanks again. I'll play with differents gains

 

[Borjam]

I have very very little experience. Mainly with Tawny owls which are very commun in my area.

I started birding a year and a half ago and with audio about half a year ago. All self-taught and learning as much as I can

I am attaching an heavily edited audio of what I think is an eagle owl, but it is an identification that raises doubts in my mind because it is not a common bird in my area.

¡Vecino! (Yo soy de Algorta)

 

[besaide]

Kaixo Borja! Elorriotik

I am attaching more examples, this morning I had to stop with an European Robin. Olympus LS P1 + home made parabolic dish with an Umbrella (50cm diameter) + High pass filter (8.4v) with PUI AOM 5024L HD microphone.

No edits, gain level 6, level 5 and level 4. There was a road with quite a lot of noise 100meter away (behind me).

I like gain level 6 the best. It is what I normally use if the bird is close enough, otherwise I use gain 8 or 10 depending on the distance.

 

[Avetarda]

I've done tests lowering the gain and the noise disappears. I was using a very high gain... I think...

 

[Vollmeise]

Egun on 😃

These are some cute results and an interesting setup, thx for sharing!

Those 5024L HD capsules do a great job, for sure they are one of the best low noise and high sensitive mic capsules available today.

Did you arrange an array of several capsules inside Your mic to raise S/N-ratio and sensivity?

I'd love to do so (at my DIY mics), but have to use plug in power right from the recording device without external power for the mics.

Here's what my DIY mics look like:





Cheers)

 

[besaide]

Kaixo Vollmeise

I read this here: https://electronics.stackexchange.c...multiple-electret-microphones-for-better-gain

" I am a technician at a boutique mic company. I like to build electret mics in my spare time.

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!) "

I did some test with 6 microphones in parallel, removing 1 each time to compare. I do not know if I did something wrong because the results were not as expected. I am attaching an image of the results. Left 6 microphones in parallel and removing 1 each time until there is only one, on the right. Conclusion: I only use 1 mic

On the other hand, I did a test with the Olympus LSP1 with its internal mics versus AOM 5024 L HD versus AOM 5024L HD with "battery box".

This test is very easy to do. You can generate the sound with audacity and a speaker: Generate - tone (waveform: sine // Frecuency 500 // Amplitude: 0.2 // Duration 10s)

Then select a part of each sound (graphic in dB) and Audacity => Analize -- Plot spectrum and check the peak decibels.

In my test, (Olympus LSP1 - Gain level 10), Left A, middle B, right C.

A) LSP1 -------------------------------------------------------------------------------> -41.7 dB
B) LSP1 + external microphone PUI AOM 5024L HD -------------------------------> -36.1dB
C) LSP1 + external microphone PUI AOM 5024L HD with "battery box (8.4v) -----> -27.8 dB

The advantage of the battery box, apart from increasing the audio level is that it cleans the low frecuencies pretty well, is very subtle.

Olympus LSP1/4 has PIP also, but the best for the mic is close to 10v : https://www.puiaudio.com/media/SpecSheet/AOM-5024L-HD-R.pdf

As I have the nikon P1000 and it uses EN-EL20 batteries, I have done all my prototypes with this battery. I go with 5 of them, 1 for the camera, one for the "battery box" of my backpack (recording all the time), one for the "umbrella-parabollic) and two more as backup

 

[besaide]

Here's what my DIY mics look like:

View attachment 1367443

This is a very good mic!!!!!! Perfect for the smarthphone and birdnet Love it!

As an idea, you could add the top of a plastic bottle, it helps to remove noise from behind, test it with a river in your back ;-)

 

[Vollmeise]

@besaide,

I did most of Your described tests also, used a parallel setup of 4 > 3 > 2 > 1 AOM 5024L capsules on a breadboard w/ stabilized power of 8,0V.

Noise decreases, sensitivity decreases, de more capsules You use.

That's why I'm using a 2+2 AOM5024 Stereo-Setup w/ dodotronics parabol attached to my sounddevices Mixpre in the fields.

The single AOM5024L-mic with TRRS-jack is for mobile phone use only.

I configured a bunch of water proof outdoor phones with huge batteries inside, but poor internal mics. These phones I can place outdoors, external AOM5024 attached, for more then a week and recording scheduled for e.g. 2
hours starting before sunrise and 2 hours starting at dawn.

An external bettery pack to power a mic array would raise quality, but would be bulky and won't last for 8-10 days.

So power issues are the reason for my cell phone setup using a single external capsule only, more noisy, but long lasting

 

[besaide]

@besaide,


An external bettery pack to power a mic array would raise quality, but would be bulky and won't last for 8-10 days.

So power issues are the reason for my cell phone setup using a single external capsule only, more noisy, but long lasting

It is very interesting what you are doing with the smathphone. I have checked recforge II PRO and it has the programming option

Good to know that I did something wrong with my test! I used also a breadboard, with "batery box" and without (50cm away from the speaker)

I have done recordings of 1 night with the olympus LSP1 with good results with temperatures over 5ºC. For lower temperatures I did an external battery. I have not put it to the limit to know how many days can be recording.

Olympus LS P1 uses an AAA battery:

1 Eneloop AAA=1.3v and 750mAh

1 Eneloop PRO AAA=1.3v and 930mAh

4 AAs in parallel:

1 Eneloop AA=1.3v and 1.900mAh ----> 4AA = 1.3v and 7.600mAh

1 Eneloop PRO AA=1.3v and 2.500mAh ----> 4 AA = 1.3v and 10.000mAh

Some photos:










Batteries are connected in parallel and added some hot glue to protect welds from jerks.



I did the hole no problem at all.









With cold days, it is very important to insulate the batteries!!!!!

 

[besaide]

And all the recorder-battery system fits perfectly in a very small box with a home made "battery box". For cold nights I would use a better insulated box.







The battery compartment is for the battery box, an EN-EL20 (nikon P1000). TRS for the recorder.

 

[Vollmeise]

@ besaide: Wow you made a huge effort!

For programming you can use any smartphone. Just download one of the automation apps like Macrodroid or Tasker and you can schedule and automate almost anything. Some tasks are a bit tricky, as the phone's energy saving settings seem to work prior to android settings and can make you desperate

As I'm a lazy one, I've chosen water proof Okitel WP6 smartphones. The internal battery is 10.000 mAh @3,7V and does it's job down to -10°C for 10-14 days.

There are lots of other phones out there, but I need a 3.5 mm jack socket and tbe WP6 does have one.

Placed some DIY camouflage around, that's what they look like now w/ external AOM5024 attached:
View attachment 1367604

And with a camouflage skirt around: