Microphone Or Capsule With Sibilance Dip

[Recording Engineer]

Has anyone done a mic (better yet just a capsule) with a drop, instead of a typical rise, in the 6k-9k range and is relatively linear every where else? The U89 is the only time I've seen something like that!

 

[Marik]

Has anyone done a mic (better yet just a capsule) with a drop, instead of a typical rise, in the 6k-9k range and is relatively linear every where else? The U89 is the only time I've seen something like that!

Do you want just a dip (i.e. with response gradually coming back on higher frequencies), or roll off (or just linear response)? We designed ground up our own capsules for upcoming condenser microphone production, and can make any voicing on the top, so if you need one with roll off we could make it for you. It will require machining the chamber with different parameters, but since we do everything in house that won't be a problem.

Best, M

 

[Recording Engineer]

Hey Marik!

In this case I was thinking of a dip with gradual rise back up... For use on a vocal.

Although, I also like the idea continued roll-off after the dip; particularly as room mics on drums or something... Even electric guitar cabinets.

By the way, just now got your 12:1 transformers in my C12-style pair... Along with a CT12 reskinned capsule with platinum coated 1-micron Mylar and a triple-mica 5751, these things are angels whispering in your ear!

 

[Marik]

Hey Marik!

In this case I was thinking of a dip with gradual rise back up... For use on a vocal.

Although, I also like the idea continued roll-off after the dip; particularly as room mics on drums or something... Even electric guitar cabinets.

While such a dip would be quite easy to make in a ribbon microphone it would probably be nearly impossible to shape in a condenser, so the roll off around that area would be the only option for what you do... or make it linear and then EQ...

Best, M

 

[Recording Engineer]

Well let's have it continue to roll-off then for my drum room mics (and possibly electric guitar cabinet) line of thought! How are we looking for that? You can tailor a capsule for that?  I'm about a month-out to fund a pair!

 

[RuudNL]

Isn't this what equalizers are made for?

 

[Tim Campbell]

Recording Engineer anyone building capsules would be able to tailor their frequency response in this way.
Ruud's suggestion is much more useful. A shelving filter will allow you to roll off top when needed but have extended frequency response when you want to record another source such as acoustic guitar. Good capsules take eq very well.

I cannot understand this modern idea of avoiding equalization at all costs and that microphones must have perfect response for a particular source without any processing. I'm sure none of your favorite music was recorded this way unless they are classical or purist jazz recordings.

 

[Recording Engineer]

I see what you guys are saying here... But I genuinely question if that's  really the case. And I look to experts actually making capsules, like you guys, and others for answers.

Can we purposely take this too extreme for a second? Business-opportunities and research aside, do we just need a couple global ultra-linear, ultra-wide bandwidth, life-capturing (or bigger than life), musically-exciting capsule options and simply EQ to application and taste? In our current technological state, I have always assumed it wasn't as simple as that because parameters may be tied-together (not completely independent) to result in the hard-to-define-thing that might considered as enjoyable musicality.

Other parameters aside and for better or worse aside, I also assume the end-results may be different enough between drastically tailoring the frequency-response at the capsule, compared to the preamplifier inside a mic, compared to after a preamp outside a mic.

But maybe with a small-range dip, even in the critical sibilant area, it just doesn't make a big-enough difference at what stage the dip occurs? However, I'd imagine there are plenty of critical-ears out there who'd maybe argue it does; a lot.

Thoughts anyone?

 

[Tim Campbell]

Sometimes there are fewer artifacts by changing the parameters at the capsule, sometimes more. You could make a narrowband mechanical filter at the capsule but the artifacts would be greater than if you simply used a well engineered equalizer especially when we are only discussing cutting frequencies rather than boosting.

I have used U89's very often. For some things they sound terrific. On other sources they exhibit unpleasant off axis phase problems.

 

[Marik]

do we just need a couple global ultra-linear, ultra-wide bandwidth, life-capturing (or bigger than life), musically-exciting capsule options and simply EQ to application and taste? ...

The on axis frequency response would not give you the whole picture of complexity of the capsule's sound and tone. The off axis information pickup and directivity (which is frequency dependent) very often are even more important. Depending on the capsule style the response will depend on distance from the source, which again, is also frequency dependent.

Different diaphragm material and thickness can also give you different tone (even though two capsules can measure the same). The tone will also be very different between aperiodic capsule designs (most of Neumann) and resonator based ones (AKG). 

Then we have controllable and un-contorllable distortions (both 'pleasant' and 'unpleasant', whatever those mean). The causes include parasitic capacitance, nonlinearity of the capacitance-to-voltage transfer, diaphragm resonances, chamber resonances, non parallel nature of diaphragm deflection in respect to backplate, etc..

So to answer your question, there will be much more than a couple 'basic' designs to cover the whole spectrum of microphone use.

Our approach is designing a linear and neutral sounding capsule, with full and balanced low end and smooth and neutral top.
The capsules are single sided 3 chambered type of the design. The system parameters chosen so that the 1st and 2nd chambers  used mostly for shaping the capsule's frequency response, and the 3rd to set time delay (without affecting the frequency response, much).  Because of such independence it allowes much easier  and more precise optimization all the parameters. Also, that independence insures superior phase integrity in off axis response, which allows to take EQ very well (the reason I mentioned it, first thing). The essential part is eliminating the capsules parasitic capacitances, so all together that provides very realistic sound picture.

Best, M

 

[Tim Campbell]

Your capsule sounds very interesting Mark. I can't wait to see and hear one

 

[Marik]

Your capsule sounds very interesting Mark. I can't wait to see and hear one

Hi Tim,

Thank you! Also, wanted to mention, a few times I used your superb CK12 re-creation and very highly regard it--great job!

Speaking of U89... it has quite an interesting capsule. Have you looked at it closely? Looking at the backplates and overall construction I wouldn't think those bigger holes go through. Are there are smaller holes connecting the chambers?

Best, M

 

[micaddict]

The on axis frequency response would not give you the whole picture of complexity of the capsule's sound and tone. The off axis information pickup and directivity (which is frequency dependent) very often are even more important. Depending on the capsule style the response will depend on distance from the source, which again, is also frequency dependent.

Different diaphragm material and thickness can also give you different tone (even though two capsules can measure the same). The tone will also be very different between aperiodic capsule designs (most of Neumann) and resonator based ones (AKG). 

Then we have controllable and un-contorllable distortions (both 'pleasant' and 'unpleasant', whatever those mean). The causes include parasitic capacitance, nonlinearity of the capacitance-to-voltage transfer, diaphragm resonances, chamber resonances, non parallel nature of diaphragm deflection in respect to backplate, etc..

So to answer your question, there will be much more than a couple 'basic' designs to cover the whole spectrum of microphone use.

Our approach is designing a linear and neutral sounding capsule, with full and balanced low end and smooth and neutral top.
The capsules are single sided 3 chambered type of the design. The system parameters chosen so that the 1st and 2nd chambers  used mostly for shaping the capsule's frequency response, and the 3rd to set time delay (without affecting the frequency response, much).  Because of such independence it allowes much easier  and more precise optimization all the parameters. Also, that independence insures superior phase integrity in off axis response, which allows to take EQ very well (the reason I mentioned it, first thing). The essential part is eliminating the capsules parasitic capacitances, so all together that provides very realistic sound picture.

Best, M

Well worth a duplication, folks.

 

[Recording Engineer]

So, for my application, it comes down to do intentional roll-off at the capsule or keep it linear?

My thought would be that a drastic roll-off at the capsule vs. keeping the capsule linear would make all electronic stages react (so to speak) differently; if all were the same. Of course, one might not design or choose the same electronics stages should the capsule responses be drastically difference.

Thoughts?

Still, I am a big fan of linear capsules!

 

[micaddict]

There's more than one way to skin a cat (nasty expression BTW), but the end results won't necessarily be the same.

Let's start with equalizing after the fact. This, of course, is very common practice and it will "do the job" in many cases.
So, can we make a U47 sound like a C12 or vice versa? Well, good luck with that.
But what if we start with a very neutral and clean sounding mic? Better odds for sure. But can you make an edge terminated capsule sound exacty like a center terminated one, both on and of axis and under all circumstances? Some may think so. I have my doubts.
Or can you take a very clean sounding microphone and make it sound like a vintage mic? In any case not by EQ-ing alone. So what if you add the needed "distortion" and such by means of digital modelling? (Slate VMS anyone?) Well, I haven't been convinced, yet.

OK, let's leave outboard EQ for now and take a look at the mic itself.  Here's more than one way to skin a cat, too. To get it to sound like you have in mind, you can manipulate the circuit or you can "voice" the capsule. Or both.
So can you get the exact same results (capsule voicing versus circuit fine tuning)?  I personally don't think so.

Fairly recently, a guy named Gousheng Zhuang started a his own microphone line (3U Audio). Since he's a  veteran capsule maker, he decided to use linear circuits and rather focus on his specialism. So he voices his capsules to get the desired results. But his starting point is not just one capsule type. (!) It's one of the the three classic capsule types, viz. a K47/49, a K67/87  or a CK12 type.  By voicing a K47 alone, he makes the mic sound more in the direction of  a  U47 or more in the direction of an M49. And by voicing a "CK12" (not a true multi-chambered one like Tim makes BTW) he either aims for the C12  or rather the Ela M251 sound. I think most here will agree that this is ball park at best. Guosheng never claimed he makes clones, mind.

The most interesting one in this regard is his U87-ish mic. Here he voices a K67/87 capsule to sort of sound like a vintage U87. But the circuit has no de-emphasis and it has zero feedback to boot. So it's all in the capsule.  To his credit I must say I've heard some very nice results that did have some of the vibe, if that makes sense.  In itself, that's quite an achievement, especially at that price point. That said, the thing may approach the original plots and even have some of "the tone", but without the original circuit it can never behave the same dynamically. Again IMO. And I'd say the differences will be most obvious on the tricky transients.

Just some food for thought.
And without scientific backup from my part for now.

 

[MS Vienna]

Speaking of U89... it has quite an interesting capsule. Have you looked at it closely? Looking at the backplates and overall construction I wouldn't think those bigger holes go through. Are there are smaller holes connecting the chambers?

The Beyerdynamic MC740 capsule is a very close relative to the K89 in general design, acoustics and materials,  just voiced a bit differently.
I owned a MC740 and I still have a capsule. Maybe those pictures are useful to you.

The build quality is outstanding. An interesting idea is the use of an O-ring between the backplates to make the air friction resistance adjustable.

Diaphragm diameter is 21,5mm, total diameter is 30mm.

And I'd say the differences will be most obvious on the tricky transients.

Yes, frequency response, be it on-axis or off-axis, is certainly important. Transient response is at least as important!
That´s why I sold my MC740 although it was an very good specimen among other MC740s I´ve heard. It just never was as pleasant as my C414comb and C414EB in the whole picture.

 

[Recording Engineer]

As a note, I was just looking at the Soyuz SU-017 response and it "in essence" also dips around the sibilance area.

 

[ricardo]

Can we purposely take this too extreme for a second? Business-opportunities and research aside, do we just need a couple global ultra-linear, ultra-wide bandwidth, life-capturing (or bigger than life), musically-exciting capsule options and simply EQ to application and taste?

Yes.

To do it properly, you have to be able to manipulate the directivity of the mike too.  It can be done with this.

https://ambisonic.info/tetramic.html
http://www.core-sound.com/TetraMic/1.php

If someone is prepared to lend me a C12 and a U47 for a year or so, I'll be happy to dream up a version that is indistinguishable.

But most people who try this find they prefer the "ultra-linear, ultra-wide bandwidth, life-capturing " version.

 

[leswatts]

We just go for a flat response in the high frequencies...that reduces sibilance a lot.

We also use EQ in the studio, but EQ doesn't know direction. Tailoring response in the mic allows us to have specific responses
in specific directions. Off axis response is super important in determining the character of a mic.

In a disk or circular cylinder end the center pressure is 10 dB higher when diameter equals wavelength... a very sharp peak. The effect is less near the disk edge. For example in a 35mm capsule the peak is at 343/.035=9.8kHz. It's directional as well.

Ways to control this peak:
1) make the capsule smaller
2) center terminate the diaphragm
3)change the edge geometry

At that frequency most pressure/pressure gradient capsules become interference pressure microphones because the delay chamber has cut off. Since they are mid tuned diaphragm inertance tends to roll off the peak.

We have a precise (in frequency and phase) impedance analogy model of this diffraction peak, so we can adjust parameters in the computer to get the desired results...a peak, flat, rolloff, perhaps a dip (never tried it). In general other parameters must be manipulated (acoustic networks) to get good control of the highest octave.

This goes for other than condenser mics...in our multi pattern ribbon in omni and supercardioid we manipulate the peak with acoustic resistance fixed to the capsule edges.

Les
L M Watts Technology
http://lmwattstechnology.com/

 

[Recording Engineer]

Les, I gotta get my hands on your mics! Same for you Mark! Tim, I've 5 of your CT-12s as you know; if that tells anybody anything!

I just have to get through this year with all my planned Barbaric Amplification tube mic projects (it will be a good couple dozen) and then start gathering a few of yall's mics over next year and the following year... Just don't be going anywhere, ok?!