The Black Hole......

Mark Johnson

Member
Paid Member
2011-05-27 3:27 pm
Silicon Valley
Final version still not available on uspto.gov

However, the application is downloadable; it is attached below. Although it looks to me like cover plate 102 is drawn backwards (!). The chamfered bolt holes "111" belong on the front of the plate, not the back. Similarly the stampy bendy 45 degree corners belong on the back of the plate, not the front.

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The claim is using a diffraction lens to widen the coverage angle of a microphone.

The only prior art claims to use diffraction to narrow the coverage!

So of course I showed actual measurements of the off axis frequency response.

The real issue is are there any security microphone manufacturers who want to see if they have deeper pockets than I do. (I have no problem with spending as much as 10e6 dollars to protect my exclusivity!). ((I once spent a quarter of that collecting a bill!)). (((Nelson if you want to talk about the Devil’s due…)))

The microphone was developed for a specific customer’s needs.

In addition to the patent there is also secret sauce in the final product. The customer has tried it and compared it to other microphones. I was a bit surprised when I looked at the existing products and saw general ignorance of the principles required.

One potential product was trying to use DSP intended for conference systems to edit the pickup. I just can’t see any of those recordings holding up in court!

The other bit of not so secret sauce is that such a microphone should survive a screwdriver attack! One manufacturer attempts this by mounting the microphone capsule well behind the mounting plate and perpendicular to the small sound admittance hole. That has around 20 dB of signal loss.
 
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That and a few others like AV should be AC. Welcoming observations!

I was fortunate enough that dyslexia was not well known when I went to school, otherwise I would have been “special Ed!” and not allowed in “advanced” classes. The only time the issue was noticed was when reading Shakespeare aloud in classes. The teacher attributed this to my books being from my home library and not the school bookshop. Explaining this was normal variation in records of Shakespeare as all examples were produced from the actors memory not the original scripts.

The worst occurred in history class when the final exam was to “compare and contrast the reign of Louis XIV to Napoleon.” I read this several times as I found it to read “Louis XIV to Louis XVI.” Fortunately the teacher went easy on me only dropping it one grade as the question I did my essay answer about was a wee bit more difficult.

Now JC has privately mention my posts often contain errrrors.
 
This is the closest competitive product. It is actually priced below my cost. However the performance is about 4% of mine. Due to our mostly logarithmic hearing the difference can be perceived but doesn’t seem quite that poor.

The other issue is the exposed microphone capsule.

Perhaps someone can explain to me the listed amplifier choice.

https://www.etsnm.com/SPECIALTY MIC DOCS/PM1-LL.pdf
 
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Hans Polak

Member
Paid Member
2005-03-17 4:25 pm
Blaricum
“Perhaps someone can explain to me the listed amplifier choice.”

Simon,
you are the microphone specialist, so what it is that bothers you about their amplifier.
Is it their 60dB S/N compared to yours 74dB S/N, and are both measured against the same reference?
Is “the higher the better” or is there a point for S/N where “enough is enough”.

Hans
 
That gives then a noise floor of 34 dBa, if that were the true figure. They are just quoting the capsule's specification. They don't add in the preamp noise. In reality the best results they get are a noise floor of 40 dBa. As a conversation in a quiet location is around 65 to 68 dBa and although you would like a 20 dB signal to noise ratio, 10 dB is often enough. That leaves about a 15 dB path length loss to pick up a conversation. So even their claim of 25 feet is a bit of a stretch. The microphones are spaced every 50 to 100 feet apart. That is why I go for 74 dB S/N. They don't even get close to handling the maximum levels without distortion.

The interesting issue is the performance adjustment controls. As soon as they are touched, no two microphones will sound the same. There is no provision for easy calibration. Another problem is the output level switch is not suitable for the actual signal levels. It will become noisy.

Most of the microphones sold for the purpose are just capsules on a cord. No additional electronics. Also not premium capsules.
 

Hans Polak

Member
Paid Member
2005-03-17 4:25 pm
Blaricum
That gives then a noise floor of 34 dBa, if that were the true figure. They are just quoting the capsule's specification. They don't add in the preamp noise. In reality the best results they get are a noise floor of 40 dBa. As a conversation in a quiet location is around 65 to 68 dBa and although you would like a 20 dB signal to noise ratio, 10 dB is often enough. That leaves about a 15 dB path length loss to pick up a conversation. So even their claim of 25 feet is a bit of a stretch. The microphones are spaced every 50 to 100 feet apart. That is why I go for 74 dB S/N. They don't even get close to handling the maximum levels without distortion.

The interesting issue is the performance adjustment controls. As soon as they are touched, no two microphones will sound the same. There is no provision for easy calibration. Another problem is the output level switch is not suitable for the actual signal levels. It will become noisy.

Most of the microphones sold for the purpose are just capsules on a cord. No additional electronics. Also not premium capsules.
Thx for your explanation.

Hans