Head Basket Shape - how it affects tonality

[rock soderstrom]

The same sort of mesh they put over cellphone microphones.

Does anyone have a source for this kind of mesh?

 

[k brown]

Okay, thanks. At first I suspected it too, but I had also looked at other photos of the mic on Google, but you couldn't really recognize it, but it makes sense!

This pic gives a better idea of the fine mesh (appears to be black):

 

[jp8]

Does anyone have a source for this kind of mesh?

Aliexpress is your friend.

https://a.aliexpress.com/_EwGwBLa

Also available in brass.

https://a.aliexpress.com/_Evg5qd2

 

[rock soderstrom]

Aliexpress is your friend.

https://a.aliexpress.com/_EwGwBLa

thanks jp8, that's exactly what I need for my test rig. I'll order a few different sizes right away...

 

[McIrish]

Do you think the headbasket shape between an M49 and U47 is the reason for the huge proximity difference? A U47 can sound huge when you get up on it but the M49 (at least the one I'm using) doesn't have that same flavor at all. The M49 is much more nuetral.

 

[GeorgeToledo]

Does anyone have a source for this kind of mesh?

You can look at McMaster Carr, they have had it when I looked last.

 

[rock soderstrom]

You can look at McMaster Carr, they have had it when I looked last.

Thanks, but I am on the other side of the pond. I have ordered different sizes from Aliexpress.

 

[Murdock]

Do you think the headbasket shape between an M49 and U47 is the reason for the huge proximity difference? A U47 can sound huge when you get up on it but the M49 (at least the one I'm using) doesn't have that same flavor at all. The M49 is much more nuetral.

I wouldn’t think the headbasket makes that much of a difference in the low end. But maybe because of resonance in the upper register it can sound like that?
Although I would say the different circuits have more impact on the lows. The M49 had a build in roll off as strong as -3dB @40Hz and feedback incorporated which should result in lower THD. The U47 did not have that strong roll off. The later short body U47 had a slight roll off but i think it can result in a slight bump at the corner frequency when the load impedance is light.

 

[OneRoomStudio]

I wouldn’t think the headbasket makes that much of a difference in the low end. But maybe because of resonance in the upper register it can sound like that?
Although I would say the different circuits have more impact on the lows. The M49 had a build in roll off as strong as -3dB @40Hz and feedback incorporated which should result in lower THD. The U47 did not have that strong roll off. The later short body U47 had a slight roll off but i think it can result in a slight bump at the corner frequency when the load impedance is light.

Interestingly, I noticed a similar thing to @McIrish in my M49 build. What I'm hearing (in mine anyway) isn't as much a a lack of true low frequencies (<50Hz), since I'm mostly using it for vocals....but less energy in the low-mids (~80-200Hz) compared to what I would expect out of a U47. I wonder if it has more to do with the particular combination of the VF14 and BV8 in the U47 as compared to an AC701 (or EC71 in my case) and BV11 in the M49. It's also possible that the shape and size of the M49 headbasket puts a singer physically further away from the capsule, reducing the proximity effect compared to a U47.

 

[McIrish]

That's great to hear you hear the same thing. I was a bit puzzled by it so that's why I started the thread. And you could be right. It might be more lower mids than actual low end, since I've only used it on vocals. Some have said that it may also be due to the U47 removing connection from the back capsule in cardioid mode, where the M49 always has an electrical connection.

 

[mrgrooves666]

That's great to hear you hear the same thing. I was a bit puzzled by it so that's why I started the thread. And you could be right. It might be more lower mids than actual low end, since I've only used it on vocals. Some have said that it may also be due to the U47 removing connection from the back capsule in cardioid mode, where the M49 always has an electrical connection.

Well at least in rev c there is a switch for true cardioid. S2 in schemo if I remember...

 

[wafelki]

Good starting starting point is to imagine the head basket as a small room with holes, standing if front of a very big loudspeaker... Which may be your mouth or a snare drum... After realizing some things... About density of air, gravity, and all... You may want to just experiment and see for yourself Laws of physics for Neumanns and MXLs are exactly the same

 

[MagnetoSound]

I wouldn’t think the headbasket makes that much of a difference in the low end. But maybe because of resonance in the upper register it can sound like that?
Although I would say the different circuits have more impact on the lows. The M49 had a build in roll off as strong as -3dB @40Hz and feedback incorporated which should result in lower THD. The U47 did not have that strong roll off. The later short body U47 had a slight roll off but i think it can result in a slight bump at the corner frequency when the load impedance is light.

How do you figure this? I think you’ll find the original U47 60M grid resistor provides much steeper LF roll-off than anything in the M49 circuit. The M49 does have global NFB, as well as the HF shunt at the plate. I can’t see anything in the original circuits that attenuates the low end.

 

[Murdock]

How do you figure this? I think you’ll find the original U47 60M grid resistor provides much steeper LF roll-off than anything in the M49 circuit. The M49 does have global NFB, as well as the HF shunt at the plate. I can’t see anything in the original circuits that attenuates the low end.

The 5Meg resistor is part of the roll off. It’s also written in the manual. If you want flat response down to 20Hz you have to unsolder that resistor else it’s -3dB at 40Hz.
But it wasn’t there in the very first version of the M49. But I would say the majority of M49’s were delivered with it.

And yes, the 60Meg in the U47 together with the 0.5uF output cap results in a roll off. But I think it’s not as steep and early as the in the M49. And earlier (long body) it was 100Meg and 1uF.

But it would be interesting to have a M49 circuit in an U47 body to compare and hear how much the headbasket alters the low end.

 

[ZHOUJUN]

I have done an interesting little experiment. I used different mesh heads on the same microphone and placed it in a soundproofing box. The microphone remained in the same position. The U47 mesh head had obviously more low frequencies. The smaller the mesh heads, the greater the impact on high frequencies. Yes, they will produce more high frequencies. Of course, they may be affected by other factors, such as there is almost no air flow when using an artificial mouth.

 

[Delta Sigma]

It is also interesting that the capsule in the vintage U67 is positioned much lower than in the re-issue.

I read somewhere that Neumann achieved the same results as the original cone with a flat disc headbasket bottom by raising the height of the capsule. Must be in a thread here somewhere.

 

[OneRoomStudio]

I have done an interesting little experiment. I used different mesh heads on the same microphone and placed it in a soundproofing box. The microphone remained in the same position. The U47 mesh head had obviously more low frequencies. The smaller the mesh heads, the greater the impact on high frequencies. Yes, they will produce more high frequencies. Of course, they may be affected by other factors, such as there is almost no air flow when using an artificial mouth.

Are you saying that smaller headbaskets increase treble pickup compared to larger headbaskets, or are you talking about the size of the holes in the mesh itself?

 

[ZHOUJUN]

Are you saying that smaller headbaskets increase treble pickup compared to larger headbaskets, or are you talking about the size of the holes in the mesh itself?

When using the U87 headband, there is a slight peak at around 10K, while when using the U67 headband, the peak is around 8K. I think the density and shape of the headband will have some effect on the reflection of the sound. This is the result of using a 20HZ-20K sweep signal. If it is a real person's voice, there will be reflection of the airflow, and the results may be inconsistent, so this only shows that the shape of the headband does affect the frequency response. This is just an interesting attempt. I can test these very easily. I used a K49 and several different headbands.

 

[k brown]

Ah, but what about the Olivia Newton-John headband?

 

[KrIVIUM2323]

The mesh's layer as well as geometry all play a role.
I heard a Josephson C725 some twelve years ago and there was something about the sound different from other valve based LDC. Sound was more solid and seemed less congested if i can say that. It could be the capsules but i'm pretty sure it's the result of random patterns and wide openings in the 'aluminium foam' headbasket.