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Old 30th October 2012, 12:57 AM   #28641
gpapag is offline gpapag  Greece
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Quote:
Originally Posted by kgrlee View Post
Not so.
so can use very stiff diaphragm materials like Ni. You can work out the pressure changes necessary to move a Ni diaphragm into the plastic range (ie it stretches) and human beings will have given up long before that.

The stiffness doesn't change.

Thank you kgrlee for commenting

Ni has to be a special case indeed.
As for more plastic diaphragms, please check pages 2-15, 2-16
http://www.bksv.com/doc/be1447.pdf

Quote:
Even lesser omnis with 'plastic' diaphragms can be used at great depth in diving chambers and at great altitude.

Correct. With the vent open.
Look at Fig. 2.6 to 2.9 of the above link.

Also Fig. 2.25 of this :
http://www.bksv.com/doc/be1373.pdf


Scott
If you are still interested on mics for infrasonics have a look on this (page 5 and on) Extreme Low Frequency Acoustic Measurement System


George
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Old 30th October 2012, 12:59 AM   #28642
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Quote:
Originally Posted by jan.didden View Post
Slightly OT (again...),

Just had a chat with Mauro Biggio the boss from Clio (his booth is nextdoor) noting that while his product gets better and better diy-interest seems to get less and lesss - could that be related to the price that gets higher and higher? Uhhh, maybe a good point.

Would there be interest in a lower cost version for diy'ers and small business? Definitely I would think!
Opinions?

jan
There is a problem that there is a multitude of free software that does the same stuff.
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Old 30th October 2012, 01:04 AM   #28643
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Quote:
Originally Posted by gpapag View Post
Scott
If you are still interested on mics for infrasonics have a look on this (page 5 and on) Extreme Low Frequency Acoustic Measurement System


George
The GE Novasensor pressure guages work just fine for me. DC to about 3.5kHz. Not too expensive either.
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Old 30th October 2012, 01:30 AM   #28644
1audio is offline 1audio  United States
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Using a Laser on a reflecting surface as a microphone is common today among the spook (intelligence) trade. Measuring the density of air to make a microphone is something Audio Technica is doing (they presented some work on ion microphones but it seemed more relevant to ion speakers.) In the late 60's I read about using a small radioisotope and a sensor to measure the air density and turn it into audio. As usual it vanished since it didn't turn into money.

The optical system seems very close to this: Fiber Optic Measurement Systems: Non-contact Measurement Sensors, Solutions and Systems - MTI Instruments which is technically simple and straightforward if you make a diaphragm (I have used one to analyze a speaker) and it works well.

B&K make an RF version of the microphone preamp that could easily have response to DC. Sennheiser has a similar technology.

A small diaphragm will have a noise problem, it can not sense as much of the pressure wave so its output will be lower than a large diaphragm.

I saw a new mike at AES that uses what appears to be 4 1'X1.5" condenser mikes in an array. Lousy hf performance but good sensitivity and that large diaphragm sound.
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Old 30th October 2012, 02:17 AM   #28645
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Quote:
Originally Posted by gpapag View Post
Ni has to be a special case indeed.
I think you'll find all the serious B&K measurement mikes use Ni. but ..

Quote:
As for more plastic diaphragms, please check pages 2-15, 2-16
http://www.bksv.com/doc/be1447.pdf
Quote:
Even lesser omnis with 'plastic' diaphragms can be used at great depth in diving chambers and at great altitude.
Correct. With the vent open.
Caught out! You are perfectly right George.

But if you have access to a diving recompression chamber, you might want to try this with a Panasonic WM61a mike. There are more holes to seal up but it is still doable.

(Pseudo) guru Lee

Last edited by kgrlee; 30th October 2012 at 02:19 AM.
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Old 30th October 2012, 02:33 AM   #28646
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Quote:
Just had a chat with Mauro Biggio the boss from Clio (his booth is nextdoor) noting that while his product gets better and better diy-interest seems to get less and lesss - could that be related to the price that gets higher and higher? Uhhh, maybe a good point.

Would there be interest in a lower cost version for diy'ers and small business? Definitely I would think!
Opinions?
I worked with Mauro in my previous life when we decided making our own production test gear for speakers was becoming a PIA. Excellent people and his level of support rivals B&K, Naerum. Some of my ideas went into ClioQC which I highly recommend to anyone doing production testing.

I introduced Clio to China and it is now a de-facto standard in Chinese factories. Sadly, there are also many Chinese clones. Please buy the original. It is not expensive for what it does & you support an excellent company.

Quote:
Originally Posted by scott wurcer View Post
There is a problem that there is a multitude of free software that does the same stuff.
Scott, what free software do you recommend for measuring speakers & mikes?

I've been searching for this mythical beast but have not found anything that is as easy to use. The closest is ARTA. But if you can afford ClioLite, buy it. Their inexpensive measurement mikes are probably the only ones whose calibration I trust.

If you do use some lesser package, I recommend you download the Clio manuals and study them carefully.
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Old 30th October 2012, 02:39 AM   #28647
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Default Optomic

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Originally Posted by kgrlee View Post
I've read the Optimic bumph and am frankly quite sceptical ... but it might be NIH syndrome on my part as I've never tried one in the flesh
Actually their latest 'specs' are much less outrageous than their original claims. Now about the level of a better than average electret omni.

Maybe they ran out of Unobtainium & virgins

Last edited by kgrlee; 30th October 2012 at 02:42 AM.
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Old 30th October 2012, 02:58 AM   #28648
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Few years ago I saw on AES subwoofers with feedback by pressure. They glued Panasonic capsules inside of a hole drilled in the case. I asked the guy if the capsule survives the pressure, he answered it even does not saturate.

By the way, probably tomorrow samples with optical capsules will be shipped. I am going to play with them and make a stereo array. If to combine them with vacuum tubes it can be a killing product!
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Old 30th October 2012, 03:19 AM   #28649
RNMarsh is offline RNMarsh  United States
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Fiber-Optic microphones: Why arent more using them and developing them further for more recording appl? Why, why, why? -RNM
Often the people who make microphones arent the best electronic circuit designers (with exceptions).... I would think that with the optical mic capsule, as it were, we here could do an excellent job of the receiving end of the light to voltage/current converter. Anyway, glad that some serious look at the technology has begun. [boy, sometimes, simple things are like pulling teeth here] Good for you - Wavebourn !! That's the spirit I like. Thx-RNM

Last edited by RNMarsh; 30th October 2012 at 03:22 AM.
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Old 30th October 2012, 03:36 AM   #28650
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Originally Posted by scott wurcer View Post
There is a problem that there is a multitude of free software that does the same stuff.
If you need to buy an external soundcard anyway, Clio may offer one with software included that's price-attractive and makes measurements a bit easier as the hardware & software should be better integrated.

jan
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