What does capsule sensitivity mean

[k brown]

My hunch is mostly sales gimmick.

 

[telewulf]

Well, may be they could print my initials in gold! ... cooool!

 

[Khron]

WHAT THE HECK IS THIS????

Why on earth would anybody make such membranes? Errr ... to emphasise certain areas and to suppress partial resonances?

https://groupdiy.com/threads/any-op...rop-capsules-as-used-by-jz-microphones.63882/

 

[abbey road d enfer]

Or perhaps ... wait a minute, I have to get my thoughts around that! ... and I have never before heard the term "parasitic capacitance" ... does that mean: at the edges (and with Neumann style in the middle as well) the diaphragm does hardly move at all and can thus be seen as a constant capacity?

Not only that, but any capacitance due to leads and PCB traces, as well as FET's gate capacitance.

A capacity, further more, that has to be viewed as parallel to the generator and thus acting as a load?

That's exctly it.

 

[soliloqueen]

i was skeptical, but metallization area does change the sound, and it can be significant, just not for the reason JZ thinks it does. Classic example of someone inventing something real by accident. telewulf is right, it's related to which areas of capacitance contribute to the final signal and nothing to do with weight at all as claimed by JZ. It's all about which waves at which frequencies oscillate the diaphragm at the places that are metalized. the diaphragm doesn't pump forward and backward like a speaker, it's more like an big set of oscillating standing waves, and different frequencies consistently are represented on different areas of the diaphragm. telewulf's intuition is quite good, he figured it out faster than its own inventor did, lol.

 

[kingkorg]

WHAT THE HECK IS THIS????

Why on earth would anybody make such membranes? Errr ... to emphasise certain areas and to suppress partial resonances?

Or perhaps ... wait a minute, I have to get my thoughts around that! ... and I have never before heard the term "parasitic capacitance" ... does that mean: at the edges (and with Neumann style in the middle as well) the diaphragm does hardly move at all and can thus be seen as a constant capacity? A capacity, further more, that has to be viewed as parallel to the generator and thus acting as a load?

@ Kingkorg: Is that what you mean by parasitic capacitance? - Interesting thought!

Best from Bremen!
Wulf

Idk if parasitic or passive capacitance is more appropriate. You see, we only care about variance of capacitance when sound hits the diaphragm. It modulates the polarizing voltage and we get AC signal.

However that variation of the capacitance is just a couple of pF at the most. The whole time we have this passive capacitance of static diaphragm in parallel which is 60-100pF for LDC, which acts as a pad and increases noise.

Ideally, capsule at rest should have 0 pF but still somehow vary in capacitance when sound hits it. There is a concept of negative capacitance to negate this, but i still haven't wrapped my mind around it.

JZ applied metalization to the areas where capsule moves the most, minimizing parasitic capacitance to an extent. The weight of the gold is too low to affect any resonance. The diaphragm cushioned by the air behind it doesn't really have resonant point in audible range once it's mounted. Especially if center terminated.

Cavities of the backplate have audible resonant point. But that’s another story.

 

[pasarski]

i was skeptical, but metallization area does change the sound, and it can be significant, just not for the reason JZ thinks it does. Classic example of someone inventing something real by accident. telewulf is right, it's related to which areas of capacitance contribute to the final signal and nothing to do with weight at all as claimed by JZ. It's all about which waves at which frequencies oscillate the diaphragm at the places that are metalized. the diaphragm doesn't pump forward and backward like a speaker, it's more like an big set of oscillating standing waves, and different frequencies consistently are represented on different areas of the diaphragm. telewulf's intuition is quite good, he figured it out faster than its own inventor did, lol.

Nice illustrations here - even for a rectangular membrane. Of course irl the modes are more irregular.

https://link.springer.com/chapter/10.1007/978-3-030-44787-8_6

 

[pasarski]

Also:

https://www.researchgate.net/figure...microphone-type-4134-at-72-kHz_fig1_233834131

 

[kingkorg]

Multiphysics is insane piece of software.

 

[telewulf]

https://groupdiy.com/threads/any-op...rop-capsules-as-used-by-jz-microphones.63882/

Wow! Thank you all for that wonderful thought-fodder ... you really sparked my brain!

Now for the first time I can see a reason why you ought to leave the outer areas of the diaphragm unsputtered (does such a word exist? Well, it does now!)

But then again: If you want to reduce the capacitance of a large diaphragm to that of a small diaphragm, you could just take a small diaphargm! As Schoeps pointed out - even in the 50ies - they come with the advantage of a much better polar pattern and that is only a logical consequence of pasarski´s drawings.

The whole time we have this passive capacitance of static diaphragm in parallel

Well, yes, but isn´t this static capacitance my "store of charge" or my "well of energy"? So how could I even want to get rid of it???

@ Ploki:
Sorry for veering off course on your thread, but it´s just so exciting

Thank you all & best wishes from Bremen
Wulf

 

[kingkorg]

But then again: If you want to reduce the capacitance of a large diaphragm to that of a small diaphragm, you could just take a small diaphargm!

Then you also reduce the "swing" of the capacitance the capsule is able to produce. Which is why SDC have in general higher noise. No free lunch.