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Learning more - Ultrasonic Microphone building
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Learning more about building ultrasonic microphones, I posted a while ago about ultrasonic electret mics. I've found the advantages of them for sure, being nice and easy. learning more and more though, I'm looking for something that gets up to 100k, like the oh-so expensive Sanken CO-100k. I've measured up to 40k on the electret mics that i'm using, which is very nice. but I want more. does anyone offer capsules that have that sort of response? If not, what are the other options for achieving this high of a response? Is the only option to build them myself? As a sound designer, I'm looking to capture the largest amount of frequencies possible.? Thank you again, you incredibly knowledgeable people!? -Soundwich |
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Lots of cheap MEMS mics go higher than 40k. Am Fr., 27. Dez. 2024 um 19:59?Uhr schrieb soundwichartist via <soundwichartist=[email protected]>:
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As Underwood suggests in his post, the ultrasonic response of some MEMS mic capsules can be quite good ...... Certainly better than most electrets in my experience.
The capsule in this unit from Micboosters :
wiil give a useful response up to around 100KHz. .... It is that capsule that gets used in many commercial bat detectors.
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You can buy just the capsule without the PCB mount - but it's very tiny and difficult to work with manually .... |
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On Fri, Dec 27, 2024 at 08:01 PM, Richard Lee wrote:
I too would be interested to learn how soundwichartist makes the appropriate measurements.....?
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I have found that measuring the detailed ultrasonic response of mic caspules is not an easy task, without access to some serious scientific equipment.
The published ultrasonic responses for cheap capsules - like Knowles MEMs and electrets - show a pretty erratic response (See Knowles App note here: )? ?
Even the expensive Sanken? CO-100k model mentioned earlier has a very non-linear HF response (see here: ).
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I've found applying the ultrasonic output from a suitable generator directly to a piezo audio 'tweeter' - like this one: ? - can give a rough idea of the ultrasonic response of a capsule......
Sadly of course the linearity of that type of transducer at ulrasonic frequencies introduces another unknown to the proceedings!
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The published ultrasonic response for the Knowles MEMs capsules can be quite useful.
I find a complex response curve like that easier to correct digitally - in post - than it would be trying to build an accurate hardware analogue filter to compensate.
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开云体育Actually it depends very much on what one expects. I think the preferred source for ultrasonic measurements is still
a spark gap. Le 28/12/2024 à 12:48, Arjay1949 a
écrit?:
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When it comes to using studio mics for ultrasonic recording - and especially for outdoor nature recording - then I think the Sennheiser MKH8020 would probably be hard to beat ? .....? Extended upper FR to at least 70KHz, and a lot more linear than other mics I've seen recommended for ultrasonics.?
Plus the advantage of 'low Z' RF technology for resistance to outdoor moisture problems.
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The only downside for amateurs like me is the price!?
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On Sat, Dec 28, 2024 at 01:44 PM, Jerry Lee Marcel wrote:
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Thank you so much for this, I had come across MEMS before but was honestly unsure about the best practices to use them. I assume its in best practice to create a PCB for them? I know for sure that would be the best case scenario for 3d printing a case for it, but is there anything else I should know about these types of microphones? I realize there is one ready and make on mic boosters, but its not really the mic shape im going for in my working prototype, so i'm definitely up for learning a little more about PCB design with an experienced friend I have. |
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To be honest, the way I measure ultrasonics might be a little crude. I honestly just attached an ultrasonic transducer to a signal generator, then 3d printed a stand for the mic and transducer to attach it to. I think i'm definitely going to go the MEMS direction, it seems to be the most straight forward way to go about what i'm trying to achieve! |
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On Sat, Dec 28, 2024 at 03:45 PM, Ivano Pelicella wrote:
I'm pretty sure that Dodotronic (along with many other ultrasonic mic manufatureres ) use the Knowles capsules I mentoned earlier: (see here: )? ?
That should give you an idea of the kind of HF frequency perfomance you might expect....
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On Sat, Dec 28, 2024 at 04:06 PM, <soundwichartist@...> wrote:
The basic micboosters capsule is very tiny and (almost) impossible to work with by hand!?
However, if you're going for a PCB you will need to create a surface mount style board, to accomodate that capsule.... That's quite brave for a first try, IMHO!
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One thing I have discovered (the hard way!) is that MEMs capsules really don't like excessive voltage applied to them..... Keep it below 3 volts, to be safe.?
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I've use a MEMs capsule in the prototype boom pole mounted? mic that? I used this last summer - in conjunction with my Zoom F3 recorder - to record bat echo location calls.? That uses the Micbooster's PCB mounted capsule, fitted into a section of 32mm plastic waste pipe, to help keep the weight down on the end of the boom pole.
Some preliminary notes on that project here: https://www.jp137.com/lts/MEMS.Ultrasonic.Interface.pdf |
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Re: measurements, I'd be very wary of the frequency response of anything you can produce with audio equipment that's not specifically designed for ultrasonics. The cheapest thing I've found for testing if you're getting some amount of ultrasonic signal up to 100kHz is a short spray from a can of computer dusting gas, but it varies hugely depending on a number of factors including how much gas is left in the can. Lately I've been using one of those pesticide-spraying bottles with a manual pump on it and running it dry with only air inside — this allows me to produce a long hiss of the same pressure for multiple tests.
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Of course this also produces an unknown frequency response, but by shooting-out against a "flat" acoustics measurement mic and a CO-100k, I can use the calibration data of each mic to get a decent-enough profile of the frequency response of my noise source. This is the best I can do for the moment, but it's accurate enough for ballpark figures, so that when I do eventually pay for fancy sound lab measurements it will be giving me detailed data I can use for small tweaks in my design.
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In terms of electret capsules, the best I've found so far is the Primo em258, but this has a pretty steep upper frequency rolloff, so your SNR at 100kHz is more than 40dB worse than it is at 20kHz, but even a Simple P48 build with this is going to give you access to frequencies that no regular studio mics will.
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As for the ultrasonic sound source (limited frequency range, obviously) could serve a "dog whistle". Or several, from different manufacturers. As I imagine that they would differ in produced frequencies.
Such a whistle (or several) connected to a cheap pressure regulator and a source of compressed air (even a car tyre will suffice or a sprayer mentioned above) is should give relatively consistent results. And be quite easy to put together.
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Easier than befriending a bat. |
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On Sun, Jan 5, 2025 at 06:51 AM, Zander wrote
I too discovered that the EM258 has a steep roll off above about 50KHz.? ?The Knowles MEMs SPU1410 capsule is a lot better than that, and at least there is a published HF frequency response for that particular capsule, which I linked to earlier- see here: ?
As you can see, it's horribly non linear, but at least the noise profile follows the frequency response, so correcting? for that maintins the S/N ratio at higher frequencies.
It's also not an easy response to correct for with simple analogue filters, so I tend to do it in post , by running my bat recordings through an appropriate EQ script.
( Some details on the last page of my ultrasonic mic notes you can find on this page: ? )
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The best ultrasonic repsonse I've seen from a studio mic is the Sennheiser MKH8020....? Bit too expensive for simple bat echo-location recordings though ! |
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I'm also interested in the topic but I would like to record well over 100k. :-)
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I recently had the opportunity to record sounds from . According to the inventor, some of the instruments produce sounds in the ultrasonic range up to 500 kHz and that the ultrasonic sounds have a positive effect on the audible frequency range. I asked how this was measured and was told that an was used to study the sound characteristics of the stone instruments. It was confirmed that the sound of some instruments was reliably measured up to about 200 kHz and beyond.
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I don't want to hijack this thread, but I would like to ask two questions.
I would like to give it a try to record the stone instrument with ultrasonic mics.
Is it feasible as a hobbyist to build a low-noise, high-sensitivity microphone to record in the audible and ultrasonic range well above 100k? Are there any instructions for building a SimpleP48Ultra maybe?!?!
Has anyone tried the Dodotronic USB Ultramics which seem to record up to 384k?
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I found the following articles by Zach Poff interesting:
and
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- Heinz
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On Sat, Dec 28, 2024 at 03:59 AM, <soundwichartist@...> wrote:
Learning more about building ultrasonic microphones, I posted a while ago about ultrasonic electret mics. I've found the advantages of them for sure, being nice and easy. learning more and more though, I'm looking for something that gets up to 100k, like the oh-so expensive Sanken CO-100k. I've measured up to 40k on the electret mics that i'm using, which is very nice. but I want more. does anyone offer capsules that have that sort of response? If not, what are the other options for achieving this high of a response? Is the only option to build them myself? As a sound designer, I'm looking to capture the largest amount of frequencies possible.? |
开云体育
Le 07/01/2025 à 11:38, Heinz via
groups.io a écrit?:
FFT analyzers going up to GHz are known, but the problem is with transducers. Typical microphones hardly go up to 200kHz. In order to measure "sounds" up to 500kHz, I believe the only way is to use constraint gauges or optical systems. Top lab work. |
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On Tue, Jan 7, 2025 at 10:38 AM, Heinz wrote:
AFAIK, the Dodotronics USB mics use the same caspules as most other commercial ultrasonic mics -- that is either a Knowles SPU1410 series MEMs or a FG series electret. (Details of those here: )?
Add to that the limited resolution of the the USB interfaces when sampling at 384KHz, and I think the quality of recording at the higher frequencies is pretty restrictive.
The next 'rung up the ladder'? - as it were - is probably the Avisoft condensers - (see here )? Considerably more expensive and still with a question mark over the resolution of 384KHz sample rate recorders.??
Above that, it's the kind of equipment Jerry describes..... But we're talking serious money, I fear!
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I'm hoping the next generation of Zoom field recorders might include a 384KHz sampling for their 32 bit float recording format.? That should put the limitations back onto the transducers!.
My undertanding is that Zoom's current 'F' range of recorders use the (now obselete) AK5388 A/D converter, which has a max sample rate of 192KHz. The current range of similar Asahi Kasei converters ( listed here: ) include sampling rates up to 768KHz.
If those higher rates are enabled in future ranges of audio field recorders, the frequency response of the recordings should become limited by the transducers, not the recorder sampling rate. |
underwood
Ivano Pelicella
Zander
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