Microphones in parallel to reduce noise

"> I'm not happy paralleling the (FET) outputs; seems like the DC

Hmm, can't you just AC couple them into the opamp?

George H.

Eeyore was essentially history, then along comes the dorko twins to feed the troll.

That's OK. Since my filter scheme relies on a "key" file rather than having to change the program, I see all kinds of possibilities for even better troll/troll-feeder filtering ;-) ...Jim Thompson

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| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
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"George Herold" whit3rd

"> I'm not happy paralleling the (FET) outputs; seems like the DC

Hmm, can't you just AC couple them into the opamp?

** Yep - as I have already said, there will be an improved s/n ratio as a result.

When several similar mic capsules are paralled - the random noise voltage drops, compared to one. However, the signal output will remain essentially the same (as from one) long as the capsules are sited together in a directional array.

This simple fact has got some here bamboozled.

..... Phil

Yep! A DimBulb clone.

That's exactly what DimBulb says, dumb donkey.

No shit? What a dumb donkey, DumbDonkey.

You read just as well as DimBulb, too. Yep, DumbDonkey an AssholeAllison really are DimBulb's DimBulb.

Allison?

That would be a 'black ho', wouldn't it?

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Offworld checks no longer accepted!

s a

oltage

y

"> ** Yep - as I have already said, there will be an improved s/n ratio as a

I saw that, sorry I didn't mention it. (Guess I was a bit cranky cause you wouldn't give me the name of a good/cheap dynamic mic... google found nothing for less than about $100. But as is usual I was probably searching for the wrong thing... half the battle is knowing what something is called.)

"> This simple fact has got some here bamboozled."

Correlation effects in noise are not always obvious. (At least it took me a while to figure it out when I first encountered it.)

George H.

For your failure to explain or show a picture or diagram of how the mics are placed, I can not determine what the purpose was. It would be a big problem to do this just to reduce noise. There has to be some kind of directionality involved. greg

Parallel arrays of identical small capsules can be used as a substitute for a large-diaphragm capsule to reduce the electrical and Brownian movement noise.

If identical in-phase signals from two capsules are combined, the resulting signal increase will be 6dB. If the random noise from two identical capsules is combined, the noise increase will only be 3dB because the two noise sources, being random, will partially cancel each other. The result is an improvement of 3dB in the S/N ratio.

This can be done with many more capsules, to give a significant improvement in S/N ratio (I have used a stack of 32 capsules for one specialised low-noise array). The result will not be quite as good as a large diaphragm, because the capsules (being round in shape) will have to be spread out over a larger area for a given size of diaphragm surface, so the phase differences between capsules for off-axis signals will be greater.

However, the capsules can be arranged in a vertical stack, which reduces phase problems in the horizontal plane at the expense of worse phase effects in the vertical plane. That may not matter as long as the performers are all in the same horizontal plane (which they often are).

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They are in a arc, 3 each side with uneven spacing and 4 touching each other in the middle about the vertex.

Steve

When you talk uneven spacing it sounds like your not trying to get high phase addition or cancellation. Its still going to be frequency dependant.

greg

What is claimed? Phased array? Directional? Selective with frequency? ...Jim Thompson

-- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

| 1962 | Help save the environment! Please dispose of socialism properly!

Directional and Noise Rejection.

Outer mics have low pass characteristics, , middle ones have peaks at high and low but are down in the mid range and inner 4 have high pass.

Steve

It asn't a problem even then with well-designed gear.

No need. It's the semi manufacturers that have produced the stunning parts available today, not the AES. 100dB dynamic range is quite routine. 120dB is not unusual on a single signal path. Try looking at app notes.

Graham

-- due to the hugely increased level of spam please make the obvious adjustment to my email address

You're a DAMN MORON !

-- due to the hugely increased level of spam please make the obvious adjustment to my email address

krw and you started the ad-hominem attacks because you have no relevant knowledge to be able to do anything else. Just like the AGW crowd in fact !

Graham

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So you support those who talk crap to make a non-existent point like the AGW crowd do you ? Make your damn mind up will you ?

Now reconsider krw's insane coment " Some "dynamics" are really electrets in drag ". Note that he is unable to post a single link to an example, just as the warmingists can't 'prove' AGW.

Graham

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...and you, DumbDonkey, really are DimBulb's DimBulb.