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Author Topic: Edge of Near Field?  (Read 2643 times)

Haolemon

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Edge of Near Field?
« on: March 21, 2011, 06:19:55 pm »

I am considering the purchase of a pair of Schoeps MK 2 S capsules, which are said to be optimized for placement at the "edge of the near field".   I understand the near field and the far (distant) field, but I am not clear on what this phrase means.  I looked around a bit on the net, but to no avail.  Could someone (Mr. Satz, perhaps ) make this a bit more clear?

Thanks

Gary Flanigan
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soapfoot

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Re: Edge of Near Field?
« Reply #1 on: March 21, 2011, 07:15:10 pm »

the definition of free field, or near field, is the area where direct sound is louder than reflected/ambient sound.  The definition of diffuse field is the opposite-- reflected/ambient sound is louder than the direct sound.

"edge of near field" would seem to suggest placement at the point where direct sound is just slightly louder than reflected/ambient sound.
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didier.brest

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Re: Edge of Near Field?
« Reply #2 on: March 22, 2011, 05:54:17 pm »

louder than reflected/ambient sound. 

I would define the far field as being the area where the reverberation (including the early reflections) is louder than the direct sound. The ambient noise (I guess that it is what you are calling ambient sound) is not involved in this definition.
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Didier Brest

David Satz

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Re: Edge of Near Field?
« Reply #3 on: March 22, 2011, 11:37:02 pm »

Hi--I apologize if the wording is unclear, but "Soapfoot" basically has it right. The MK 2S was designed for placement at or near the so-called "critical distance" or "reverberation radius"--the distance (which depends on the size and absorptive characteristics of the room) at which the direct sound energy of what you are trying to record is more or less equal to the reverberant sound energy.

Omnidirectional microphones of normal size (i.e. large enough to be quiet enough for the great majority of professional applications) can't be perfectly omnidirectional because at high frequencies, their diaphragm dimensions equal or exceed half of the sound wavelengths. Thus at high frequencies their off-axis response drops below their on-axis response to some extent.

If you're recording from close range, where nearly all the sound energy of interest is arriving directly on-axis, you probably want a microphone with basically flat on-axis response (e.g. Schoeps MK 2 capsule). If on the other hand you are recording from so far away that most sound energy is reflected and reaches the capsule at more or less random angles of incidence all around, then you probably want a capsule that has flat response under those conditions (e.g. Schoeps MK 3).

In other words, the MK 2 is considered "free-field equalized" while the MK 3 is considered "diffuse-field equalized." The other two Schoeps capsule types (MK 2H and MK 2S) are between those two extremes, and since the miking distances most commonly used in live classical two- or three-microphone stereo recording fall somewhere between "quite close" and "quite distant" it's no surprise that the MK 2S and MK 2H outsell the MK 2 and MK 3.

--The problem with the term "ambient sound" is that it has at least two quite different meanings to different people: it can mean the sum of all reflections of whatever you are trying to record (i.e. the reverberation in the room)--or it can mean the noise and other interfering sounds which are present in the space where you are trying to make a recording of something.

--best regards
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