Topic: Neumann Omni Question

[stevetoney]

OK, as a relative newcomer to the really nitty gritty details of this hobby, I don't understand what the difference, in laymans terms, between the AK30 and AK31 omni capsules are.  Can someone explain this to me in common terms.  For example, I don't understand the following terms; diffuse field equalized vs. free field equalized and free sound field vs. diffuse sound field. 

I guess the real bottom line is, which is more appropriate for live music recording?

***

AK30 Description
It is a diffuse field equalized pressure transducer with a flat frequency response up to 10khz (in the diffuse field). In the free sound field this microphone has a boost of approximately 7db at 10khz.


AK31 Description
AK 31 is a free-field equalized pressure transducer. The sensitivity in the free sound field is flat up to 20 kHz. In the diffuse sound field there is a roll-off above 5 kHz.


Thanks oh great and knowledgeable Icculus.

Steve

[stirinthesauce]

The 130 would be better suited for PA taping (IMO) as generally you are taping at a distance.  The slight HF bump will produce some directional charecteristics of the mic.  The 131 is better suited for being close to the sound source (really close), which most of the times tapers are not.  Of course if using in onstage applications, the 131's may be better.  I've owned free field omnis and used to great results.  I currently own diffuse field omnis and use those to good results as well.  Differring applications require different mics.

I'm not great at explaining mic characterstics as some so here is something I snagged from Michael Hartkopf's old page.

[Diffuse-Field (-Equalization)
The expression diffuse-field means a field of sound that consists of reflexions (reverberations, echo). It is the opposite extreme of the free-field. In fact any room and most locations outside are mixes of free-field and diffuse-field. The nearer to the source, the more the free-field conditions rule over the diffuse-field conditions and vice versa. An important set of points in the room is the radius of reverb. The radius of reverb is the set of all points where the intensity of direct sound is equal to the intensity of all reverbs and echoes. In opposition to free-field equalized microphones, diffuse-field equalized ones respect the fact that when they are addressed from the rear, their diaphragm is in their own shadow of sound and by this have a reduced sensitivity at high frequencies. So diffuse-field equalized microphones have a light treble-boost (don't confuse it with a presence-boost, which has a fall towards the high frequencies!) while free-field equalized ones are ruler flat. Diffuse-field equalized microphones are used in the distance from the source, where there is more reverb and echo than direct sound. The typical application is as ambience mic.

Free-Field (-Equalization)
The expression free-field means a field of sound without any reflexion (reverberation, echo). The sound spreads from the source into all directions and either travels to infinity or is killed at the borders of the field (anechoic chamber etc.). In the free field, there is direct sound only. A free-field equalized microphone is constructed in a way that the sound that arrives the diaphragm from the front causes a ruler flat frequency response curve. Free-field equalization ignores the effect that the dimensions of the microphone itself must be taken into account when sound addresses the mic from the rear, because in this case the diaphragm is in the sound-shadow of the microphone. Free-field equalized microphones shall be used anywhere direct sound is stronger than reverberation. i.e. inside the radius of reverb. Because main mics, such as AB, MS or OSS/Jecklin disk, must be set up inside the the radius of reverb, free-field equalized mics are the right selection for these applications. The nearer the mics at the radius of reverb the more they may have a little (!) treble boost.

more from Hartkopf on subject

Omnidirectional
Often it is a highly underestimated Polar Pattern. It has no preferred direction, which means it picks up sound from any direction with almost the same intensity. Because it is a Pressure Transducer that works behind the omni pattern, we get an extended bass response, no close-up effect, a clear and linear reproduction through the whole frequency range. The frequency response is constant in a very large angle around the microphone. Unfortunately, the larger the capsule the larger the difference between a free-field equalized element and a diffuse-field equalized one. The dimensions of the capsule itself must be observed when viewing at the sound field. In case sound comes from the rear to the mic, the diaphragm is in the sound-shadow of the whole mic (including capsule). This results in a small loss of trebles. So you have to decide whether you want to use the mic in a distance from the sound source (where is more reverb than direct sound) - e.g. as ambience mic - or inside the radius of reverb, where there is more direct sound than reverb. Diffuse field equalization results in a bit of treble boost. For distant miking, you have to select a diffuse-field equalized omni microphone, and for close miking (including AB setups, OSS/Jecklin discs, MS setups) the correct selection is a free-field equalized omni microphone. However, in fact, the more distant to the sound source, the more treble boost the mic may have.
Single-diaphragm omni capsules are constructed a as closed cylinder of which the front end is the diaphragm. Only a very tiny hole allows the atmospheric pressure to go into the capsule (otherwise it would be a barometer). Sound cannot pass the hole, so it is acoustically tight.

edited for late night brain fart.  Confused on model numbers.

[DSatz]

Free field = a fairly extreme situation in which nearly all sound reaches a microphone directly, "free" of obstacles and sound-reflecting surfaces, i.e. in an anechoic environment, or at some elevation outdoors--or else so close to the sound source(s) that the microphone picks up little if any reflected sound.

Diffuse field = the extreme opposite in which there is little if any direct sound. The angles from which sound reaches the microphone are essentially random; the path lengths (and thus the arrival times) from the sound sources to the microphone are extremely diverse. In a pure diffuse sound field there is no possibility of localizing any sound sources.

These two terms, and the scenarios they represent, are familiar to acousticians; measurement microphones are always one or the other. Neither extreme corresponds to the typical usage of omnidirectional microphones for modern stereo recording of music, however. For a variety of reasons having to do with the size of a microphone and the effect that this has on its pickup pattern at high frequencies (causing even an "omnidirectional" microphone to become distinctly directional), some kind of choice is unfortunately necessary.

Neumann offers only those two strongly defined types; most other manufacturers' omnidirectional microphones fall in between those two extremes, however, because an in-between characteristic will generally fit better with contemporary recording practice. When these two types are the only alternatives, however (as it is currently with Neumann and as it used to be with Schoeps, for example), people's preferences vary: Classical engineers tend to go for the free-field type more, while pop and rock engineers go for the diffuse-field type. This is because the free-field type would simply sound lacking in high frequencies when placed at typical stereo recording distances in a normally reverberant space. The diffuse-field type suffers from an excess of high frequencies in such placement--but where pop and rock are concerned, "too much" seems to be preferred over "not enough," while for classical (especially classical musicians, as opposed to engineers and producers) it is often the other way around.

With the small Neumanns the polar patterns of the two types are absolutely identical, so you could choose either one, make your recordings, then use an equalizer to make the result sound just as it would have sounded if you'd used the other type of mike instead. Or you could record with either type of microphone and equalize it to some point between the two extremes, which would usually sound better anyway.

--best regards

[stevetoney]

Both responses...awesome!  Thanks, that really helps and FWIW, I searched the archive and this seems to be the first such response on this subject so it's really appreciated. 

By the way...both of you truly are Icculus!!!

[silentmark]

+t's 

[DSatz]

tonedeaf, thank you (I think), but is an Icculus like a cross between Icarus and Daedalus, or is it more like a succubus doing calculus while on cannabis?

--best regards

[illconditioned]

Thanks!

Could you explain *why* a diffuse field will behave as it does?  In other words, there is some physical process that gets less high frequencies to the mic from reflected sources?  Is it just that high frequency components decay as they reflect (so the diffuse mic compensates for this with a high frequency boost)?

OK, if the high frequencies dissipate, what is the *ideal* diffuse source?  We know the ideal free field source is an anechoic chamber, what is the ideal diffuse source?

By the way, this was explained to me in another way.  Someone told me that a diffuse source is like putting the mic on an (infinite?) surface and putting that mic + surface in an anechoic chamber.

Oh yeah, suppose I've got a "standard" omni mic like a DPA4060.  Is that diffuse or near field, or some compromise?  Is this listed in the spec sheet?

Ah, shit, now I've confused myself.

  Richard

[stevetoney]

tonedeaf, thank you (I think), but is an Icculus like a cross between Icarus and Daedalus, or is it more like a succubus doing calculus while on cannabis?

--best regards

Icculus was the mythical prophet in Phish's imaginary Gamehenge saga.  This was Trey Anastasio's senior project, which he created and set to musical form when he was in college many many years ago.  It was actually quite an innovative and insightful story that is not unlike the story of the Hobbit in Lord of the Rings.  Obviously, it's a looooong story, but to make it short, there was a book...the Helping Friendly Book...that was written by the great and knowledgeable Icculus.  That means that the characters of the story were intended to 'read Icculus'.  Get it?  Read-Icculus...ridiculous!!!  Trey has that kind of sense of humor!

Anyhow, I liken the knowledge that you have to that contained in the Helping Friendly Book!!!  Thank you very much!

[F.O.Bean]

Also, what he is saying is, if you pointed the free field, say directly vertical(upwards), then it would have a slight HF bump at 5kHz regarding the sound source, right?

But the diffuse field, it doesnt matter where its pointed regarding the sound source, it will still have a HF bump, correct? which is DEF necessary from far-field recording IMO as omnis can pack a PUNCH, especially at jamband shows.....

[DSatz]

illconditioned, a diffuse sound field is built up from the reflections in a room. The sound is bouncing off the walls (literally) as well as the floor, ceiling, people, furnishings, etc., and with each bounce there is some attenuation because some of the sound energy turns into miniscule amounts of heat. The thing is, this happens very unevenly at different frequencies, with high frequencies being absorbed more than midrange frequencies in general. Even just traveling through the air, the losses are a little greater at high frequencies, but the main high-frequency losses come from absorption when sound is reflected.

Add to this the fact that an omnidirectional microphone isn't omnidirectional at these same high frequencies--if you want flat response on axis, you pay for it with rolled-off response off-axis. The standard frequency response curves which the manufacturers all print are free-field response curves, meaning that they show the microphone's frequency response for sound arriving as "plane waves" on the 0-degree axis of the microphone. Move 30 degrees to the right or left, however, and the picture changes considerably at high frequencies. That information is contained in the polar response graphs which, unfortunately, not very many people know how to read (but it's not actually hard to figure out, and HUGELY worth learning).

There is no typical environment that produces an ideally diffuse sound field in the sense that an anechoic chamber offers an ideally direct (free) sound field. You can approach it in some large Gothic cathedrals where the sound hangs around in the air for six or seven seconds after a singer has already let go of a note, but it is a theoretical construct as is the perfect anechoic chamber (real ones all have limits and problems).

I'm not very familiar with DPA's product line so give me a moment to go look. Or better yet, let me tell you what I would be looking for, and then I don't have to go look. If this is a microphone of the more or less usual diameter for a small-diaphragm condenser, then it will show an on-axis elevation of several dB (5 - 6 - 7 - 8) at around 8 - 9 - 10 - 11 kHz if it is a diffuse-field type. (For smaller microphone diameters the frequency range would be higher.) A free-field type will always have flat high frequency response on axis; in a sense no one cares about its off-axis response since essentially no sound is reaching it from off-axis anyway.

If the microphone is made to be extremely small then these distinctions will no longer matter within the audible range. That may seem like the ideal, but it's not--because such small microphones have rather high equivalent noise levels and anyway, most engineers seem to find that their recordings sound better with some directionality in the microphones at high frequencies, though I suppose that could vary with the circumstances and with people's personal tastes (he said, trying to avoid any arguments with Earthworks users).

I hope this answers your questions to some extent.

--best regards

[easy jim]

Once again many thanks DSatz for the excellent and informative posts.  +t

[stevetoney]

Pretty obvious Neumann put alot of thought into the design of the AK30 and AK31.  What's somewhat interesting is that they haven't ever modified the design of the AK50 to offer an additional option to match what the majority of music recordists desire in that capsule...namely the warmer boost on the low end of the hyper capsule.  I think most music people prefer a warmer version of the AK50.  Oh well, guess that Neumann can't make every variation to meet every desire and need of every sub-group that uses their products.

Thanks once again for such insightful input on this interesting subject.

Steve

[anhisr]

I just "fix" the AK50 in post.  I have even saved the eq so I don't have to set it every time.  Just made it look more like the AK40 cap. 

[F.O.Bean]

I just "fix" the AK50 in post.  I have even saved the eq so I don't have to set it every time.  Just made it look more like the AK40 cap. 

Now thats a GREAT idea. Care to share what settings you have it preset for? Hmmm, I need to hear more of your recordings, Jerry. I guess I could go thru that Phish you sent me. I transferred all but like 6 shows so far

Might have to get some ak50's and ak40's then. Always LOVED the ak40 sound!

[DSatz]

tonedeaf, the Neumann AK 50 is evidently a compromise between the requirements of close speech and general applications (including music recording), with the speech applications coming out somewhat ahead in the bargain (-10 dB at 50 Hz). One could assume that film and video dialog recording and high-end P.A. systems were the primary market that Neumann envisioned for this capsule. But its directionality is very consistent across the audio frequency range, and as a result, what anhisr describes is a perfectly reasonable strategy for music recording.

One of the "secrets" of making a microphone respond well to equalization is to keep its polar pattern as consistent as possible across the audio frequency range; the other is to start from basically flat frequency response, i.e. a generally neutral/natural/transparent sound quality, without much if any special "personality" or "character." Most of the capsules in Neumann's KM 100/KM 180 series have a certain "sparkle" to them as the result of their slight high-frequency enhancement, but it's not glaring--just a slight push in a glamorous-sounding direction.

It's not an emphasis that I usually prefer because I mainly record trained professional musicians who already have the good stuff in their own sound; adding a layer of simulation onto the real thing doesn't generally give a very convincing result. But in some respects that little bit of built-in EQ can make untrained voices sound more like trained ones, which certainly is a neat trick.

--best regards

[anhisr]

Bean, I didn't start "fixing" my AK50 tapes until recently.  The shows I sent you were not "fixed" yet. I will post my setting as soon as I have time too. 

[stevetoney]

Bean, I didn't start "fixing" my AK50 tapes until recently.  The shows I sent you were not "fixed" yet. I will post my setting as soon as I have time too. 

...and does this 'fix' satisfy you regarding the needed/desired amount of warmth, balance, or whatever?

[anhisr]

yep.  More of a warmth thing. 

[anhisr]

Bean, you are quite the slut 

[DSatz]

tonedeaf, a lack of "warmth" in a recording is one thing that can often be improved with fairly simple equalization. A friend of mine built what he called a "warm filter" once, which was just a Radio Shack box containing a couple of op amps with a shelving boost at around 250 Hz as I recall.

Let me just say that when I was active as a studio engineer, the older guys all used EQ with a degree of skill that I think has become almost a lost art. As far as I could find out, they used EQ as a matter of course on nearly all the live recording that they ever did, often in relatively small amounts such as 2 dB here or there, but knowing when and where to apply it was a thing which they'd learned through decades of practice.

I see that EQ has a bad reputation today--people seem to think that it spoils the "purity" of their sound--but I chalk that up to using too much in the wrong place, and also to some wishful thinking about how "pure" their sound is to begin with.

--best regards

[illconditioned]

Hey DSatz, I've got another question for you about "warmness":

I'm been recording with DPA 4060 lately, and find there is some kind of "harshness" in the sound.  All the frequencies seem to be there, and there is tons of detail, but I find the guitar amplifier, in particular, to sound harsh.  I don't think this is how it sounded in the room, either.  The mic seems to be doing something to it, but I can't say what.

The clip is at: http://soundmann.com/2007-11-10-NathanColes_clip_dpa4060_eq.mp3
I'm not sure if I applied EQ or not, but it didn't really change the sound.

Comments?
  Richard

[DSatz]

The clip sounds a bit "glassy" to me. Spectrum analysis shows a sizable bump in the octave around 2 kHz, and I'd prefer less of that, or maybe none. I say that with caution since my computer loudspeakers are nothing serious and I don't know what kind of sound you like. But if your reaction resembles mine, you could try reining in the 1.5 to 3 kHz region by a couple of dB to see whether that gets at what's bothering you.

--best regards

[illconditioned]

The clip sounds a bit "glassy" to me. Spectrum analysis shows a sizable bump in the octave around 2 kHz, and I'd prefer less of that, or maybe none. I say that with caution since my computer loudspeakers are nothing serious and I don't know what kind of sound you like. But if your reaction resembles mine, you could try reining in the 1.5 to 3 kHz region by a couple of dB to see whether that gets at what's bothering you.

--best regards

Thanks!  I'll try to play with the EQ.  I'm wondering if there is more to it, though.  These mics are constructed quite differently than "classic" electrets.  They have a thin gold plated (mylar?) sheet, but it is rectangular, and not tensioned.  Instead it is just resting on the (articulated) backplate.  This probably accounts for the detail, but may be causing some of the weirdness as well.

 Richard

[illconditioned]

The clip sounds a bit "glassy" to me. Spectrum analysis shows a sizable bump in the octave around 2 kHz, and I'd prefer less of that, or maybe none. I say that with caution since my computer loudspeakers are nothing serious and I don't know what kind of sound you like. But if your reaction resembles mine, you could try reining in the 1.5 to 3 kHz region by a couple of dB to see whether that gets at what's bothering you.

--best regards

Hmm.  On second thought, could this 2k boost be caused by having the mics on my hat?  Anyway, even if reduce the frequency near 2k, it still sounds a bit "sharp" for my liking.  Maybe it did sound like that in the room, I don't know.  But it doesn't sound good on the recording!

 Richard

[KLowe]

I see that EQ has a bad reputation today--people seem to think that it spoils the "purity" of their sound--but I chalk that up to using too much in the wrong place, and also to some wishful thinking about how "pure" their sound is to begin with.

--best regards

This is THE MOST QFT statement I've read all year.  I'm firmly in the EQ to taste camp.  I have never understood all of the "EQ ruins the tapes" B.S.

DSatz...... you are a man among men.

[Tim]

I see that EQ has a bad reputation today--people seem to think that it spoils the "purity" of their sound--but I chalk that up to using too much in the wrong place, and also to some wishful thinking about how "pure" their sound is to begin with.

--best regards

This is THE MOST QFT statement I've read all year.  I'm firmly in the EQ to taste camp.  I have never understood all of the "EQ ruins the tapes" B.S.

DSatz...... you are a man among men.

My reservation is that many people don't know what they are doing and don't have good monitors to do the work on.

[Gutbucket]

The clip sounds a bit "glassy" to me. Spectrum analysis shows a sizable bump in the octave around 2 kHz, and I'd prefer less of that, or maybe none. I say that with caution since my computer loudspeakers are nothing serious and I don't know what kind of sound you like. But if your reaction resembles mine, you could try reining in the 1.5 to 3 kHz region by a couple of dB to see whether that gets at what's bothering you.

--best regards

Thanks!  I'll try to play with the EQ.  I'm wondering if there is more to it, though.  These mics are constructed quite differently than "classic" electrets.  They have a thin gold plated (mylar?) sheet, but it is rectangular, and not tensioned.  Instead it is just resting on the (articulated) backplate.  This probably accounts for the detail, but may be causing some of the weirdness as well.

 Richard

The interchangeable 'grids' on the DPA 4060 change the mic's high frequency response by creating a little resonant bump depending on the length of the grid tube.  The mics come with two different length grids, but some people also use them without the grids, presumably to get a flatter (possibly rolled-off?) high end response.  Below is a response chart showing curves for both grids for the DPA 4060. There is no published response data that I know of for the mics without any grid. The longer grid creates a bigger, peakier bump that is designed to help accommodate common lavaliere placement for announce/stage voice work.  I don't think many use the long grid for recording music.   

I wonder if the resonant tube design of the grids has something to do with what you're hearing, Richard.  I've thought about using some brass tube bits and experimenting with different tube lengths & possibly cutting the tube end at an angle to broaden the peak.  I've also thought about doing that to make the mic more side address oriented which would be beneficial for some of the ways I use them.  I realize that I probably shouldn't notice much directionality, given their extremely small size, the data from the DPA polar plot and my 4+ decade old ears, but I do hear some of the airy top end roll-off when off axis, so I point them appropriately. 

I almost always prefer the short grids. I do notice the emphasis which I often find useful at the distances from which I typically record, but can sometimes be a bit bright near cymbals for instance.  The only time I've found the long grid useful for music is when putting the caps flush on opposite sides of a 8" ball to emulate something like the Schoeps KFM6. I believe the omni caps in the KFM6 are diffuse-field eq'd or have some sort of additional high shelf boost (D.Satz, please correct me if I'm wrong), so it would seem that by using the longer grids perhaps I'm creating a more boosted diffuse field response curve suitable to a stereo sphere mic application? I only use that technique in the center of a circle of acoustic musicians, which is a different application than what the KFM6 is designed for in any case. 

Here's the polar plot & response graphs with the two grids, from DPA's site-

[Gutbucket]

Here's the 4060 polar plot-

[DSatz]

gutbucket, many thanks for the juicy diagrams but the frequency range that I find to be exaggerated in this recording is lower than where the peaks are in those diagrams. What I'm hearing is "too much of a good thing" in a frequency region near where most people's hearing is at its most sensitive.

That other stuff way up top is kind of--not the icing on the cake; icing is far more important than that. It's more like whether a few chocolate sprinkles on the whipped cream on top of the icing on the cake are glazed sprinkles vs. unglazed sprinkles.

I should really find out what type of microphone this is. The odd thing is that its polar diagram implies a rather small capsule (1/2" or maybe even smaller?) without much rolloff in its off-axis response at high frequencies. But when you have that characteristic, you no longer need a high-frequency boost in the 0-degree response (normally required in larger omni microphones that are intended for distant pickup, to bring up their diffuse-field response to something like flat). So the whole acoustical design is a bit of a puzzle to me--it seems like a special-purpose item which would only be needed in a hall full of overstuffed pillows (or people, perhaps).

--best regards

[Gutbucket]

^^^
That's why I figured I'd post the charts.. as you mention, the mic's response peaks are higher in frequency.  I just listened to the sample and hear the presence boost on the guitar but not the vocals, so maybe its due to the mic location more than the mic's inherent response? Could be directly on-axis with the guitar amp? Just a guess.

As for DPA's odd 4060 design- it's an extremely small back-electret lavalier mic, originally targeted towards stage and announce work and built to survive sweat, makeup, etc.  It has a very small 5.4 mm diaphragm that is oriented vertically, half of which protrudes from the cylindrical brass body of the mic. When one of the protective grids is installed the entire capsule in then 'inside the tube' facing to the side. Even though the capsule faces sideways, it's still a end address design and is measured that way in the polar plot. DPA makes several different sensitivities to match with different wireless manufacturers and most people around here have the lower sensitivity 4061 model which are commonly found used from stage productions.  The self noise and signal to noise figures are better for the hotter 4060 version however, and personally I find the 4061's a bit noisy for acoustic music. 

The mics became popular around here and for music recording in general because of their small size and their transparent sound.  Since their introduction, DPA has developed mounts to mic pianos, close-mic brass, guitars & violins, and now has a system of small preamp/stereo pan/summing boxes that chain together and feed a stereo mix to the board for the whole section.  Blasphemous as it may be for classical music, each members of a string section has their own small preamp and stereo sum buss chained to the next member with a single stereo feed for the whole section.

So it is a bit of a special purpose item and I'd guess that any frequency bump was initially engineered for 'on the actor' placement and happened to work out well for some music applications too.


4060 specs-
 
Sensitivity, nominal, ±3 dB: 20 mV/Pa; -34 dB re. 1 V/Pa
Equivalent noise level A-weighted: Typ. 23 dB(A) re. 20 µPa (max. 26 dB(A))
Equiv. noise level ITU-R BS.468-4: Typ. 35 dB (max. 38 dB)
Total harmonic distortion (THD): <1% THD up to 123 dB SPL peak
Max. SPL, peak before clipping: 134 dB
S/N ratio, re. 1 kHz at 1 Pa (94 dB SPL): 71 dB(A)
Dynamic Range: Typ. 100 dB

Microphone length: 12.7 mm (0.5 in)
Weight: 7.5 g (0.26 oz) incl. cable and connector

[illconditioned]

^^^
That's why I figured I'd post the charts.. as you mention, the mic's response peaks are higher in frequency.  I just listened to the sample and hear the presence boost on the guitar but not the vocals, so maybe its due to the mic location more than the mic's inherent response? Could be directly on-axis with the guitar amp? Just a guess.

As for DPA's odd 4060 design- it's an extremely small back-electret lavalier mic, originally targeted towards stage and announce work and built to survive sweat, makeup, etc.  It has a very small 5.4 mm diaphragm that is oriented vertically, half of which protrudes from the cylindrical brass body of the mic. When one of the protective grids is installed the entire capsule in then 'inside the tube' facing to the side. Even though the capsule faces sideways, it's still a end address design and is measured that way in the polar plot. DPA makes several different sensitivities to match with different wireless manufacturers and most people around here have the lower sensitivity 4061 model which are commonly found used from stage productions.  The self noise and signal to noise figures are better for the hotter 4060 version however, and personally I find the 4061's a bit noisy for acoustic music. 

The mics became popular around here and for music recording in general because of their small size and their transparent sound.  Since their introduction, DPA has developed mounts to mic pianos, close-mic brass, guitars & violins, and now has a system of small preamp/stereo pan/summing boxes that chain together and feed a stereo mix to the board for the whole section.  Blasphemous as it may be for classical music, each members of a string section has their own small preamp and stereo sum buss chained to the next member with a single stereo feed for the whole section.

So it is a bit of a special purpose item and I'd guess that any frequency bump was initially engineered for 'on the actor' placement and happened to work out well for some music applications too.


4060 specs-
 
Sensitivity, nominal, ±3 dB: 20 mV/Pa; -34 dB re. 1 V/Pa
Equivalent noise level A-weighted: Typ. 23 dB(A) re. 20 µPa (max. 26 dB(A))
Equiv. noise level ITU-R BS.468-4: Typ. 35 dB (max. 38 dB)
Total harmonic distortion (THD): <1% THD up to 123 dB SPL peak
Max. SPL, peak before clipping: 134 dB
S/N ratio, re. 1 kHz at 1 Pa (94 dB SPL): 71 dB(A)
Dynamic Range: Typ. 100 dB

Microphone length: 12.7 mm (0.5 in)
Weight: 7.5 g (0.26 oz) incl. cable and connector

The interesting thing is the rectangular diaphragm.  It is (apparantly) not tensioned like a circular one, but just lying on a backplate (with ridges in it).  Similar designs are used by Knowles Acoustics (for hearing aids) and Sanken (so-called "vertical diaphragm).  As I said in an earlier post, I feel that this capsules has a *qualitatively* different sound than the classic "cylinder" mic.

  Richard