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Measurement Mic. Diy Help
Measurement Mic. Diy Help
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Old 6th September 2017, 01:07 PM   #1
Jishu is offline Jishu
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Default Measurement Mic. Diy Help

Dear, Gurus
I want to diy a precision measuring mic (thr ones that require an electret microphone); I have read a few articles and guides but they are pretty old, and I was just not able to find Panasonic WM61A nor WM61AY nor any of the alternatives. I searched the net but I could not find any new guides. Is the diy electret measuring mic died with that panasonic model going obsolete?
I would really like to make one and ask you of recommending an alternative to the panasonic model or maybe a new guide completely. I could buy from both digikey.in and mouser.in or also from amazon.in and ebay.in.
Thank you.
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Old 6th September 2017, 10:28 PM   #2
PRR is online now PRR  United States
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Panasonic WM-61A Mic Capsule to be discontinued

> not able to find Panasonic WM61A nor

They can be found, but not from P-Sonic and maybe under another number.

DigiKey lists two alternates from PUI, a long-time mini-mike supplier who probably contracts Asian factories for P-Sonic work-alikes. The $2 model looks good to me. More looking-around would be wise.

This CUI is very flat, though they don't plot below 100Hz.

This eBay vendor is offering JLI mikes with graphs that are very flat for a good price.

Making a small f-l-a-t omni is not rocket science. They have become a commodity, like resistors. The design tends to a bass-droop and a top-ring. Some have more of both for better speech intelligibility. Others let the bass run below 50Hz, and mini-capsules tend to have enough damping to control (not eliminate) the top-ring.

Last edited by PRR; 6th September 2017 at 10:31 PM.
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Old 4th November 2017, 09:17 AM   #3
Jishu is offline Jishu
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Quote:
Originally Posted by PRR View Post
DigiKey lists two alternates from PUI, a long-time mini-mike supplier who probably contracts Asian factories for P-Sonic work-alikes. The $2 model looks good to me. More looking-around would be wise.

This CUI is very flat, though they don't plot below 100Hz.
thank you.

Quote:
This eBay vendor is offering JLI mikes with graphs that are very flat for a good price.
the shipping is about 20 times the product, could not afford it.

Quote:
Making a small f-l-a-t omni is not rocket science. They have become a commodity, like resistors. The design tends to a bass-droop and a top-ring. Some have more of both for better speech intelligibility. Others let the bass run below 50Hz, and mini-capsules tend to have enough damping to control (not eliminate) the top-ring.
could you recommend some guides?

And I am sorry for being late almost abandoned the thread. I downloaded a ton of datasheets from mouser.in and after a while after after reading 23 datasheets I found this:

AOM-5024L-HD-R PUI Audio | Mouser India

what do you think? is this good enough? please do reply...
thank you.
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Old 4th November 2017, 06:02 PM   #4
PRR is online now PRR  United States
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Good mike but the Mouser page shows none in stock.
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Old 4th November 2017, 07:49 PM   #5
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Originally Posted by PRR View Post
Good mike but the Mouser page shows none in stock.
its a new product, they will restock it. what do you say, i get one?
would this be better than the panasonic wm61a?
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Old 4th November 2017, 08:00 PM   #6
lholland is offline lholland  United States
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Measurement Mic. Diy Help
Just FYI. I recently spoke to a guy deep into this part of the industry (a measurement mic mfg) and he said that the Panasonic mic element was the foundation of most low cost measurement mics on the market and that Panasonic's decision to end production was a huge hit to a lot of OEM's.

He also said that as of this time their isn't a replacement with the sample to sample consistency and reliability that the Panasonic unit had, thus this segment of mic OEM's is still looking for a solution. Many of the better OEM's are now buying larger batches, testing each element and tossing the outliers.

Not a pretty situation, but a DIY'er can buy (10) or so and sort through them with the proper measurement equipment.
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Old 5th November 2017, 01:36 AM   #7
1audio is offline 1audio  United States
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Measurement Mic. Diy Help
However, without a reference how do you select good elements? Things like reciprocity measurements are not really possible with an active electret. To my knowledge no one has made an electrostatic actuator for this type of microphone. it would be interesting to try to make one.

Free field measurements need reference mikes. This is expensive but a good way. However there are a ton of pitfalls in even comparing measurements between microphones if the physics of how they interact with the acoustic fields aren't addressed.

I could see someone setting up a service testing elements and sorting them. But it would be time consuming and not cheap. Is there enough interest to get this off the ground? (I have the essentials but would need to find a high school student with appropriate skills and patience to do it.)
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Old 5th November 2017, 01:11 AM   #8
wintermute is offline wintermute  Australia
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Measurement Mic. Diy Help
There were people around that would calibrate your diy mic, though I don't remember the details. I know there was one here in Aus, and pretty sure there was someone offering the service in the US, though I can't remember how expensive it was. Now that relatively cheap calibrated mics are available, it may no longer be worthwhile.

If you have a VERY flat mic (like the panasonic WM60AY) then one way to get an idea of how accurate it is (in the higher frequency ranges) is to measure a reputable tweeter and compare to manufactures published curves. If the results are very close (as they were in my case) then you can probably safely use it uncalibrated.

It all depends on what you are trying to achieve. If you mainly want it for crossover modeling, provided it doesn't have any big anomalies in your crossover region you will probably get decent results with an uncalibrated mic, provided you don't put too much empahsis on "correcting" for spl differences in the upper or lower octaves where you may be getting incorrect readings from your mic. You would be better off trusting manufacturers (or simulations in the lower octaves) curves there.

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Last edited by wintermute; 5th November 2017 at 01:12 AM. Reason: add simulation comment.
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Old 5th November 2017, 01:24 AM   #9
scott wurcer is offline scott wurcer  United States
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Quote:
Originally Posted by 1audio View Post
Free field measurements need reference mikes. This is expensive but a good way.
I had good luck with the spark discharge method for 500Hz - 20kHz once I found the right literature. For absolute SPL and low frequency response I used a homemade piston chamber and a medical pressure gage ($15) which is calibrated and goes to DC. It was strain gage based and had response out to 3k or so. They sold our mic business before I could cross calibrate.
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Last edited by scott wurcer; 5th November 2017 at 01:28 AM.
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Old 8th November 2017, 12:43 PM   #10
Ultima Thule is offline Ultima Thule  Europe
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I too have been looking long for a microphone suitable for my budget DIY stuff, had just a look at Mouser and checked through only a few, especially the brand CUI Inc. seemed to have a few new interesting microphones, some of them are already in stock at Mouser.

CMC-4015-25T CUI | Mouser Europe
CMC-6027-24T CUI | Mouser Europe
CMC-6027-32T CUI | Mouser Europe

Attached PDF's of the 3 above link examples, perhaps someone with better understanding on microphones could comment on these.
Attached Files
File Type: pdf cmc-4015-25t microphone - CUI.pdf (448.7 KB, 13 views)
File Type: pdf cmc-6027-24t microphone - CUI.pdf (396.5 KB, 11 views)
File Type: pdf cmc-6027-32t microphone - CUI.pdf (368.8 KB, 8 views)
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