Effect of capsule height in head basket

[McIrish]

I was looking at on of my recent capsule swaps and I noticed the capsule was a bit high in the head basket. The upper part of the capsule is covered slightly by the head basket top structural band. That got me wondering about tonal changes due to head basket and capsule height. Anyone care to elaborate?
The mic is a Miktek CV4 and the capsule is the Ari Flat 47. The capsule comes with the holder but not the post. The only post I had at the time is a little too tall. I already ordered another one to test out.

 

[kingkorg]

I was looking at on of my recent capsule swaps and I noticed the capsule was a bit high in the head basket. The upper part of the capsule is covered slightly by the head basket top structural band. That got me wondering about tonal changes due to head basket and capsule height. Anyone care to elaborate?
The mic is a Miktek CV4 and the capsule is the Ari Flat 47. The capsule comes with the holder but not the post. The only post I had at the time is a little too tall. I already ordered another one to test out.

I just made the measurements, as i was in the middle of something similar. Sorry, no images of the setup, some proprietary stuff going on.

Anyways, lowest shape is the capsule with no headgrille, middle shape is capsule 2mm from the upper cap of u47 style grille, so as high as it goes, upper shape is the capsule in the middle of the grille.

The levels are separated so you can see easily the difference in shapes.

So yes, as i pointed many times before, everything around the capsule is crucial for the sound. As important as the capsule itself.

 

[McIrish]

Wow! I would not have expected that much difference. Very good to know. Thanks for posting the chart.

 

[kingkorg]

Wow! I would not have expected that much difference. Very good to know. Thanks for posting the chart.

Some images just to ilustrate what the positions were.

 

[McIrish]

The top of my capsule is just covered by the top band around the head basket, so it's not as extreme as yours looks. I've got a new post coming today so I will find out if I hear the difference. Granted... the top of my hearing range is somewhat diminished. age...

 

[Murdock]

As always great stuff @kingkorg !
It seems the closer the capsule is to the base it acts a little like a de-esser...
maybe that’s also part of why the u47 is so revered as a vocal mic.
Although it is not so extreme in the U47 I think. The capsule sits a little bit further up.

 

[kingkorg]

As always great stuff @kingkorg !
It seems the closer the capsule is to the base it acts a little like a de-esser...
maybe that’s also part of why the u47 is so revered as a vocal mic.
Although it is not so extreme in the U47 I think. The capsule sits a little bit further up.

Exactly. However this is just effect of the grille, no body attached to it. The body adds whole nother level of complexity to the sound. This is the reason i love building mics designed to be transparent in this respect, like Elam, u87... The goal is to avoid these effects, so the transparent the better. With u47 type mics, you have to nail all these imperfections, which is a nightmare. So many variables.

Edit:
Also the notch frequency will vary with every millimeter of headbasket diameter variation. The notch on 0° axis is most likely present as sharp boost in FR at 180°.

 

[Андрій Чубака]

So all this placing level can change level of sound recording and maybe can change signal to noise ratio. Or I am not correct understand it.

 

[kingkorg]

So all this placing level can change level of sound recording and can maybe can change signal to noise ratio. Or I am not correct understand it.

No, i made the difference in the level so it's easier to see the difference in the response shape. The level and snr are the same.

 

[terry setter]

Tube Neuman U47s (at least the long body version with the chrome cap) have the capsule high enough that the headbasket's top structural band slightly covers the diaphragm. I end up ordering Thiersch's longest post to try to emulate that placement.

 

[McIrish]

I ordered a different post/holder from Peluso. I got it on Friday and installed it. Kind of a PITA, as it's a bit hard to creat a hole template that works perfect. Anyway, It's the same as the last one I got. It's a much nicer one and has some vibration dampening but still it's not quite what I had hoped for. Maybe I will look at the one from heisermann.
Right now, it sits exactly like a K47 sits in the headbasket of the U47. The metal band just slightly covers the upper area of the capsule. Maybe I should leave it and move on with life... Probably obsessing over something that may not make much difference.

 

[living sounds]

Headbasked geometry/material and bottom geometry/material matter as well. Try some foam below the capsule, it will sound quite different.

 

[terry setter]

Or, here's a favorite approach of mine (photo). The well-damped, semi-circular wad of plastic below the capsule improved the sound of the mic appreciably. I had been concerned about all the flat surface area below the capsule in a mic that is about 3 inches wide. This proved to be the solution in our case. I've used foam, too, but I hate how it turns into sticky goo and begins to flake after only a few years.

 

[kingkorg]

Or, here's a favorite approach of mine (photo). The well-damped, semi-circular wad of plastic below the capsule improved the sound of the mic appreciably. I had been concerned about all the flat surface area below the capsule in a mic that is about 3 inches wide. This proved to be the solution in our case. I've used foam, too, but I hate how it turns into sticky goo and begins to flake after only a few years.

This is a nice solution, however if one is going for the accurate replica of say u47 which has the flat platform you have to nail the complete geometry around the capsule to nail the sound. And that's where the nightmare starts.

 

[terry setter]

And that is only one of so MANY nightmares when trying to replicate the U47! By the way, I used the term semi-circular, when I should have said that it was a section of a sphere. Guess I was in a hurry. Fortunately, that design was not intended as a clone, but as something that would fall roughly between the U47 and 251, particularly in regard to perceived brightness.

 

[Marik]

That's how we deal with reflections and resonances. Note, there is no basket around the capsule--the head is the capsule itself. The holder is made as an acoustical lens. Any obstacles (rings, sidebars, etc.) around the capsule will affect the sound. The carbon fiber body is dead to resonances.

Best, M

 

[Marik]

Here is our approach to SDC cardioid back wents

 

[k brown]

Yeah, diffraction is a thing . . .

Ask any speaker designer about the headaches it can bring.