What does capsule sensitivity mean

[Ploki]

What does mic capsule sensitivity mean in practice?

Seen numbers from 34-42dB

Does that mean 6dB gain difference in the same circuit?

Does it affect noise floor, frequency response?

 

[Khron]

The sensitivity of the capsule itself, you'll rarely (if ever) see specified. The sensitivity of an entire microphone though, is a far more frequent spec.

Where exactly have you encountered those numbers?

 

[kingkorg]

I oversimplified things here, but MicUlli filled in with more details. It's slightly different when it comes to electret capsules, and ones with built in electronics. Most manufacturers pull specs out of thin air, so i would just disregard them. In general, smaller capsules have more noise and are less sensitive, but there are exceptions.

Sensitivity depends on the whole circuit, and polarization. True condenser capsule doesn't have inherent sensitivity value.

@kingkorg:
True condenser capsule doesn't have inherent sensitivity value.

Not correct. Condenser mic capsule sensivity is given in mV/(V*Pa). (Unloaded output voltage/(Sound pressure*Polarisation voltage)) at least for DC excited capsules...
BR MicUlli

 

[Ploki]

Thanks!

I got the numbers off Ali capsules.
They’re still 50€/piece so i dont want to order so many different just to see what’s up

 

[Khron]

Spoilers: "specs" on AliExpress are worth less than the electrons used to display them on your screen...

 

[OneRoomStudio]

I oversimplified things here, but MicUlli filled in with more details. It's slightly different when it comes to electret capsules, and ones with built in electronics. Most manufacturers pull specs out of thin air, so i would just disregard them. In general, smaller capsules have more noise and are less sensitive, but there are exceptions.

Does this measurement (mV/(V*Pa)) have any direct relationship to the capacitance of the capsule? I imagine there are other factors that have an impact (diaphragm material, amount of gold/conductive material, diaphragm size, acoustic loading due to backplate holes, etc), but it seems like capacitance is one of the biggest factors in sensitivity.

 

[Ploki]

Spoilers: "specs" on AliExpress are worth less than the electrons used to display them on your screen...

I can’t really find any capsules around europe that aren’t rebranded Ali as far as i can tell (and as far as i read kingkorg’s posts here) or that aren’t used neumanns for a grand lol.

I did contact two suppliers on Ali and they said they can send matched pair.

 

[kingkorg]

Does this measurement (mV/(V*Pa)) have any direct relationship to the capacitance of the capsule? I imagine there are other factors that have an impact (diaphragm material, amount of gold/conductive material, diaphragm size, acoustic loading due to backplate holes, etc), but it seems like capacitance is one of the biggest factors in sensitivity.

Capacitance plays a role, but not direct and absolute. Diaphragm damping and compliance are a huge contributor too. Take a look at this thread.

There is a caveat though. The graph above is level matched. The modded capsule is 3.5db less sensitive. By increasing damping, the capsule stifnes is increased, and sensitivity reduced. As the original goal of u67 design was to reduce noise, it is quite logical why they went with brighter and louder capsule and then further reduced noise by adding HF deemphasis part of the circuit.

Unadjusted graphs:

 

[RuudNL]

What to think of the specification of a condenser capsule: output impedance-200 Ohm.

 

[OneRoomStudio]

What to think of the specification of a condenser capsule: output impedance-200 Ohm.

No impedance converter necessary! Just wire it straight into the preamp.

 

[k brown]

All Lying Information Express

 

[rogs]

What to think of the specification of a condenser capsule: output impedance-200 Ohm.

Welll...... it can depend on the configuration. To quote Sennheiser's Manfred Hibbing :
"The impedance of a condenser capsule of 40 pF capacitance decreases with rising frequency from 200 MΩ at 20 Hz to 200 kΩ at 20 kHz.
At high (radio) frequencies - for instance at 10 MHz - the impedance is reduced to 400 Ω "

So a condenser capsule could be considered pretty low impedance when used in an RF mic configuration....
... but not in a 'standard' DC configuration of course !

 

[telewulf]

Crack me if I´m wrong, but my thoughts travel along this line:

Sensitivity means you put in an alternating pressure of air and you get alternating voltage out - hence mV/uPa.

-> With a dynamic capsule this is very straight forward because all the energy required for the transduction is taken from the moving air itself.

-> With an electret capsule it is rather straight forward too, because the voltage output is in a fixed relation to the alternating pressure as well, if you keep the surrounding circuit within reasonable specs.

-> But with a NF condenser capsule it is not at all straight forward at all, since the alternating voltage is also depending on the direct voltage the capsule is charged with, not to mention the fact that due to the incredebly huge source impedance your sensitivity also depends on the following impedance converter or the fact that the capacitance responsible for the signal is not the 50 - 100 pF but must nessisarily be a delta-value as well.

So to me the term "sensitvity" does not make any sence what so ever in relation to a condenser capsule. - But then again Ploki didn´t specify a certain type of tranceducer when he kicked off the thread:

What does mic capsule sensitivity mean in practice?

So Ploki, you asked what it means in practice and I answered what it means in theory - Sorry for that!
To me it is absolutely impossible to seperate the two - absolutely my fault!

So what kind of capsule was it, that you were offered for 50 Quid?

Best wishes from Bremen,
Wulf

 

[Voyager10]

What does mic capsule sensitivity mean in practice?

Seen numbers from 34-42dB

Firstly, these numbers should be given as -34dBV, -42dBV. Leaving off the minus sign and 'V' (volts) is careless but commonly done.

So -40dBV is 10^(-40/20) = 10^-2 V = 10mV.

This is (by convention) quoted at 94dB SPL, this is 1Pa in air pressure terms. So "-40dBV" sensitivity is the same as 10mV/Pa.

For an externally polarised (non electret) capsule, the full specification should give a polarisation voltage. Sensitivity is directly proportional to this voltage. If it's not given, 48V is a reasonable guess.

 

[k brown]

I think capsule sensitivity is the measure of how easily insulted it is.

For example the capsule in the Blue Snowball is a total snowflake; you really have to watch your language around that mic!

 

[Ploki]

Crack me if I´m wrong, but my thoughts travel along this line:

Sensitivity means you put in an alternating pressure of air and you get alternating voltage out - hence mV/uPa.

-> With a dynamic capsule this is very straight forward because all the energy required for the transduction is taken from the moving air itself.

-> With an electret capsule it is rather straight forward too, because the voltage output is in a fixed relation to the alternating pressure as well, if you keep the surrounding circuit within reasonable specs.

-> But with a NF condenser capsule it is not at all straight forward at all, since the alternating voltage is also depending on the direct voltage the capsule is charged with, not to mention the fact that due to the incredebly huge source impedance your sensitivity also depends on the following impedance converter or the fact that the capacitance responsible for the signal is not the 50 - 100 pF but must nessisarily be a delta-value as well.

So to me the term "sensitvity" does not make any sence what so ever in relation to a condenser capsule. - But then again Ploki didn´t specify a certain type of tranceducer when he kicked off the thread:



So Ploki, you asked what it means in practice and I answered what it means in theory - Sorry for that!
To me it is absolutely impossible to seperate the two - absolutely my fault!

So what kind of capsule was it, that you were offered for 50 Quid?

Best wishes from Bremen,
Wulf

Thanks for the elaborate answer!
i'm eyeing these two:
https://www.aliexpress.com/item/1005005133720880.html
https://www.aliexpress.com/item/1005005997124664.html

One is -34dB and the other is -42dB. Judging by the gold pattern of the membrane i'd assume the fancy-patterned one is less sensitive since it covers less contact area. But this is really going by dumb conjecture

I agree there's a lot of things listed on there that only make sense when paired with a mic preamp circuit

 

[kingkorg]

Judging by the gold pattern of the membrane i'd assume the fancy-patterned one is less sensitive since it covers less contact area.

But then, it also has less parasitic capacitance.

 

[Ploki]

But then, it also has less parasitic capacitance.

Huh. Would parasitic capacitance manifest as ringing/resonances at higher frequencies?

 

[abbey road d enfer]

Huh. Would parasitic capacitance manifest as ringing/resonances at higher frequencies?

Parasitic capacitance manifests itself as lack of sensitivity and distortion.

 

[telewulf]

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