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Topic: recording between 20Hz and 80KHz (Read 14215 times) previous topic - next topic
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recording between 20Hz and 80KHz

does anyone know a cost sensitive way to record audio between 20Hz and 80KHz?
quality is nice but the principal constraint is the frequency response range.

thanks for any help you could provide.

recording between 20Hz and 80KHz

Reply #1 –
Quote from: noireanqa on
does anyone know a cost sensitive way to record audio between 20Hz and 80KHz?
quality is nice but the principal constraint is the frequency response range.

thanks for any help you could provide.


Any of a goodly number of computer audio interfaces work well up to 96 KHz.  Search on 24/192.

Your biggest problems would be microphones and speakers.  There are speakers that work up to 100 KHz or so, but they are mostly very directional, so the sweet spot is limited. There is also quite a bit of atmospheric absorbtion in the 50-100 KHz range.

recording between 20Hz and 80KHz

Reply #2 –
Quote from: Arnold B. Krueger on
Any of a goodly number of computer audio interfaces work well up to 96 KHz.  Search on 24/192.

Your biggest problems would be microphones and speakers.  There are speakers that work up to 100 KHz or so, but they are mostly very directional, so the sweet spot is limited. There is also quite a bit of atmospheric absorbtion in the 50-100 KHz range.


great, so any of the common 24bit, 192KHz recording boxes would suit me? do you know of any portable ones that obviate the need for a computer? i need to record cats for extended periods of time and would prefer not to also have to buy a dedicated computer and leave it at the animal sanctuary solely for recording purposes.

recording between 20Hz and 80KHz

Reply #4 –
Quote from: noireanqa on
does anyone know a cost sensitive way to record audio between 20Hz and 80KHz?
You probably want to record digitally at 192 kHz sampling rate, which is not much of a problem these days. If you need a microphone, then your choice is rather limited. A (1/4 inch) measurement microphone might be your best option. In general the noise specs are not terrible, but 80 or even 100 kHz bandwidth is possible. I only know a few rather pricy versions. Perhaps others can chime in for more affordable ones

http://www.bksv.com/Products/TransducersCo...hones/4954.aspx
http://www.microtechgefell.de/eng/prod/mes...301/mk301_0.htm
http://www.earthworksaudio.com/our-microphones/m-series/m50/

recording between 20Hz and 80KHz

Reply #5 –
Quote from: odigg on
Look around some online audio stores for a portable audio recorder.  Make sure you check and verify the specs to make sure the microphones can actually record the frequencies you need.

Examples are below.

http://www.bhphotovideo.com/c/product/6994...#specifications

http://www.bhphotovideo.com/c/product/5241...tml#accessories


im thinking the korg mr1, how does it look to you?
http://www.korg.co.uk/products/digital_rec...r_mr1_specs.asp

i'd have to record in 1bit to get to 100KHz, but i think it looks like a good option. does anyone have experience with these units?

recording between 20Hz and 80KHz

Reply #6 –
Quote from: Kees de Visser on
Quote from: noireanqa on
does anyone know a cost sensitive way to record audio between 20Hz and 80KHz?
You probably want to record digitally at 192 kHz sampling rate, which is not much of a problem these days. If you need a microphone, then your choice is rather limited. A (1/4 inch) measurement microphone might be your best option. In general the noise specs are not terrible, but 80 or even 100 kHz bandwidth is possible. I only know a few rather pricy versions. Perhaps others can chime in for more affordable ones

http://www.bksv.com/Products/TransducersCo...hones/4954.aspx
http://www.microtechgefell.de/eng/prod/mes...301/mk301_0.htm
http://www.earthworksaudio.com/our-microphones/m-series/m50/


this mic problem is going to be tough .. im unfortunately on a really tight budget. hmm ... maybe i could rent one.

recording between 20Hz and 80KHz

Reply #7 –
Quote from: noireanqa on
im thinking the korg mr1, how does it look to you?
http://www.korg.co.uk/products/digital_rec...r_mr1_specs.asp

i'd have to record in 1bit to get to 100KHz, but i think it looks like a good option. does anyone have experience with these units?
You'd "have" to record in 1-bit? No, that's for the DSD/SACD format, which is another kettle of fish entirely. Someone else would have to advise on whether or not it would be at all suitable, but it's certainly not directly comparable to PCM.

I thought you only wanted to get to 80 kHz? That unit supports 192 kHz, which will get you all the way to 96 kHz.

recording between 20Hz and 80KHz

Reply #8 –
Quote from: dv1989 on
You'd "have" to record in 1-bit? No, that's for the DSD/SACD format, which is another kettle of fish entirely. Someone else would have to advise on whether or not it would be at all suitable, but it's certainly not directly comparable to PCM.

I thought you only wanted to get to 80 kHz? That unit supports 192 kHz, which will get you all the way to 96 kHz.


oh, in which case i believe im misunderstanding something.
on the page i saw:

Quote
Frequency Response:
10Hz ~ 20kHz ±1dB @ Fs44.1/48kHz, 10Hz ~ 40kHz ±1dB @ Fs88.2kHz/96kHz/176.4kHz/192kHz, 10Hz ~ 100kHz (1 bit)


could you explain what 10Hz ~ 40kHz ±1dB @ Fs192kHz means?

thanks for all your help so far everyone, its really very appreciated.

recording between 20Hz and 80KHz

Reply #9 –
Quote from: noireanqa on
Quote from: dv1989 on
You'd "have" to record in 1-bit? No, that's for the DSD/SACD format, which is another kettle of fish entirely. Someone else would have to advise on whether or not it would be at all suitable, but it's certainly not directly comparable to PCM.

I thought you only wanted to get to 80 kHz? That unit supports 192 kHz, which will get you all the way to 96 kHz.


oh, in which case i believe im misunderstanding something.
on the page i saw:

Quote
Frequency Response:
10Hz ~ 20kHz ±1dB @ Fs44.1/48kHz, 10Hz ~ 40kHz ±1dB @ Fs88.2kHz/96kHz/176.4kHz/192kHz, 10Hz ~ 100kHz (1 bit)


could you explain what 10Hz ~ 40kHz ±1dB @ Fs192kHz means?

thanks for all your help so far everyone, its really very appreciated.

My guess is that they use 192kHz to relax on filter specs, not to increase bandwidth.

For most music purposes that is perfectly sane, but for your purpose it might be bad.

-k
 

recording between 20Hz and 80KHz

Reply #10 –
Quote from: knutinh on
My guess is that they use 192kHz to relax on filter specs, not to increase bandwidth.

For most music purposes that is perfectly sane, but for your purpose it might be bad.

-k



aah i see. hmm, this is trickier than i thought. the equipment seems to exist but i only have a budget of around £300
i figured i could buy the recorder and rent the microphone but finding a mobile recorder that uses 192kHz is harder than i imagined

recording between 20Hz and 80KHz

Reply #11 –
Quote
this mic problem is going to be tough .. im unfortunately on a really tight budget. hmm ... maybe i could rent one.


Therea are very few mics that respond even up to 40 KHz, let alone 80. Theones that come to mind are in the $1k - $2K range, and not exactly common at pro audio rental places. Remember that the rentals for pro audio geear are different than renting a car or a house - the rental company basically wants to make their money back every 30 days ir not sooner.

recording between 20Hz and 80KHz

Reply #12 –
B&K 4135 or 4136 or 4139 should do the job. Keep in mind that they require 200V polarization, not 48V like pro-audio microphonea. So you would have to buy/rent an appropraite preamp or entire sound level meter. B&K sould level meters usually have "AC" output, which is basically line-out.
Ceterum censeo, there should be an "%is_stop_after_current%".

recording between 20Hz and 80KHz

Reply #13 –
A crazy idea maybe, but here goes...

Would it be possible to use a sensibly priced conventional portable recorder to simultaneously record the sound up to 20kHz on one channel via a conventional mic, and content up to 80kHz (and possibly well above) on the other channel via the headphone output socket of a hand-held bat call detector?

This won't give a true seamless encoding covering the entire frequency range required as the bat call detector output will be frequency shifted downwards, but all of the information required will be there in one form or another, and in sync on the stereo channel pair.

It might then be possible to import both channels into an audio editor at a later stage, pitch shift the bat call channel upwards appropriately, then mix it with the conventional audio channel to at least crudely reconstruct the entire 20Hz to 80kHz spectrum as one signal in a 192kHz samplerate final encoding.

Apologies if the above seems a little unconventional and doesn't achieve exactly what the OP needs as a single-pass solution, but tight budget constraints often lead to the requirement of a little additional effort and some 'out of the box' thinking.

recording between 20Hz and 80KHz

Reply #14 –
Quote from: Slipstreem on
A crazy idea maybe, but here goes...

Would it be possible to use a sensibly priced conventional portable recorder to simultaneously record the sound up to 20kHz on one channel via a conventional mic, and content up to 80kHz (and possibly well above) on the other channel via the headphone output socket of a hand-held bat call detector?

This won't give a true seamless encoding covering the entire frequency range required as the bat call detector output will be frequency shifted downwards, but all of the information required will be there in one form or another, and in sync on the stereo channel pair.

It might then be possible to import both channels into an audio editor at a later stage, pitch shift the bat call channel upwards appropriately, then mix it with the conventional audio channel to at least crudely reconstruct the entire 20Hz to 80kHz spectrum as one signal in a 192kHz samplerate final encoding.
I was thinking of suggesting that literally right before I read your post! I’m doing some work with bat detectors at the moment, one of which performs frequency division, i.e. shifts the input down by a defined factor (typically 10) so it can be heard by humans, and indeed recorded by more general equipment.

Also, my bad for not noticing the info on that recorder’s response, or considering the upper limits of microphones.

recording between 20Hz and 80KHz

Reply #15 –
Quote from: noireanqa on
i need to record cats for extended periods of time...
Sounds like an interesting project. Can you share a bit of background information ?
I've found that "The hearing range of the cat for sounds of 70 dB SPL extends from 48 Hz to 85 kHz, giving it one of the broadest hearing ranges among mammals."
Are you also supposed to (electrically) generate sounds up to 80 kHz? Finding a suitable transducer (speaker) for that won't be easy either.

recording between 20Hz and 80KHz

Reply #16 –
I've done up to 40khz or so for acoustic testing of materials.  I used a pair of NI DAQ cards, labview and a piezo microphone and tweeter.  Neither were remotely linear in the region, but if you don't mind giving up some SNR on the DAQ cards you can calibrate and linearize them easily enough.

recording between 20Hz and 80KHz

Reply #17 –
I tested the Zoom H1 recommended by odigg and was rather surprised that in 96khz mode it is able to record up to 48khz quite lineary. For the test I recorded accoustic instruments which have a rich amount of harmonics. There isn't much of a noticeable drop in energy up to 48khz.

recording between 20Hz and 80KHz

Reply #18 –
Quote from: Northpack on
For the test I recorded accoustic instruments which have a rich amount of harmonics. There isn't much of a noticeable drop in energy up to 48khz.
Did you use the built-in microphones ? Most microphones "drop" above 20 kHz, but gradually, like most analoge devices, so it's quite normal to see energy up to 48 kHz.

recording between 20Hz and 80KHz

Reply #19 –
Quote from: Kees de Visser on
Did you use the built-in microphones ? Most microphones "drop" above 20 kHz, but gradually, like most analoge devices, so it's quite normal to see energy up to 48 kHz.

True, but what I have seen so far drops considerably around 30khz, so that there isn't much left, if any, at 48khz. I don't think I have ever seen a "purple" amount of energy at 48khz

It's done with the build in mics. I think those small diameter electrets are quite efficient at high frequencys. They are used as measurement microphones after all.

recording between 20Hz and 80KHz

Reply #20 –
The problem is that we don't know how the natural frequency response of the recorded instrument should look like. But even if we optimistically assume a linear drop from 200Hz to 48kHz (black line), the device would have a response of an approx. -15db at 48khz: