Microphones for below threshold of Hearing

[amirm]

Cool demo from Grass on their very low noise microphone (G.R.A.S. 40HF ):

 

[McFly]

Um, why isn’t this technology in ALL studio recordings

 

[solderdude]

Um, why isn’t this technology in ALL studio recordings

sing into it with the same gain settings and you will know

 

[RayDunzl]

Um, why isn’t this technology in ALL studio recordings

Can't find a price so that makes me assume $$$$$

+ the required phantom power (200V)

+ (maybe) the required preamplification

 

[McFly]

Sorry was my emoji not good enough for sarcasm

 

[solderdude]

mine wasn't as well ?

The S/N ratio was impressive though.

 

[RayDunzl]

https://www.geonoise.com/wp-content/uploads/2016/09/GRASProductCatalogue-2016.pdf

 

[McFly]

It is a shame we can’t have 300db SNR mics. What about a coaxial or tri-axial(?) mic that is microprocessor controlled to switch the lower ones off as the levels get higher?
We’d need the ears to hear it.

 

[PierreV]

It is a shame we can’t have 300db SNR mics. What about a coaxial or tri-axial(?) mic that is microprocessor controlled to switch the lower ones off as the levels get higher?

Oh, but we do have those. The problem is that they are both permanently attached to Rob Watts head.

 

[ZolaIII]

Meh you can buy a great mic with 17 dB self on noise & 140+ dB LPS for 160$ which is both omni & directional & I doubt you will ever need better one.

 

[McFly]

Oh, but we do have those. The problem is that they are both permanently attached to Rob Watts head.

But then I went to -400db and started hearing angels talking to me

 

[dasdoing]

a simple contact microphone should work for the glass jar

 

[jlo]

With those mics, you would need the very best A/D converters ..... but sorry no 200V phantom
https://www.stagetec.com/en/product...matrix/analogue-audio-components/xmic-en.html

 

[Blumlein 88]

I have a microphone that is rated at 4 dbA for self noise. Only 6 db higher than this one. I've not tried recording caterpillars or leaf munching snails. I'd suspect the issue might be the low noise preamplifier. My microphone is rated for 29.8 mV/pascal while the G.R.A.S. is 1.1 v/pascal. I assume that is with their preamp in use which probably provides 30 db of gain or so. It also looks like they did this in some sort of anechoic chamber. I was wondering how do you block out other noise to have a chance hearing the creatures they are listening to. An anechoic chamber would help in that regards.

The microphone comes with the low noise preamp and you get either a 1 channel or 10 channel power module for the 200 volt phantom power.
https://www.gras.dk/products/product/229-12HF.html
Probably need the 10 channel rig or two for doing full Atmos surround recording.

 

[scott wurcer]

I have a microphone that is rated at 4 dbA for self noise. Only 6 db higher than this one. I've not tried recording caterpillars or leaf munching snails. I'd suspect the issue might be the low noise preamplifier. My microphone is rated for 29.8 mV/pascal while the G.R.A.S. is 1.1 v/pascal. I assume that is with their preamp in use which probably provides 30 db of gain or so.

There are techniques for having gain right in the impedance converter. It's not that hard to reach the Brownian motion noise of the air then it gets down to a lot of esoteric issues, B&K has a good (free) paper on this. They are also using 20-40G Ohm impedance levels which requires some care in design. I once bought a lot of used capsules and one of them had a big gob of dried tobacco spit inside.

 

[STUDIO51]

I used GRAS 43BB. Obviously, the noise level was low, but the maximum input limit was low. Difficult to measure earphones simulating ear canal resonance (+8 ~ 18dB) at 3kHz

In addition, since the microphone diaphragm is very flexible, it is necessary to couple earphones and stabilize for 1 minute. Otherwise, you can see the measured value continuously changing for one minute.

 

[scott wurcer]

I used GRAS 43BB. Obviously, the noise level was low, but the maximum input limit was low. Difficult to measure earphones simulating ear canal resonance (+8 ~ 18dB) at 3kHz

In addition, since the microphone diaphragm is very flexible, it is necessary to couple earphones and stabilize for 1 minute. Otherwise, you can see the measured value continuously changing for one minute.


View attachment 69627

If you do the research the slack diaphragm is one of the tricks.