Measuring Capsule Membrane Resonance

[molke]

Can one maybe calculate it when knowing the volume of the air behind the membrane?

One certainly can (as e.g. in the Shure paper). I tried and failed. The easiest might be an equivalent circuit (lumped elements) in a circuit simulator. Unfortunately, this doesn’t work that well for predicting the response at the resonant frequency (Figures 5–7).

 

[GeorgeToledo]

Not super relevant to the omni discussion, but going back some posts…

There is info about these Neumann testers on one of the historical audio gear sites that’s mainly in German. Forgetting the name of the site at the moment but there is info out there.

I thought it was capacitance over frequency that these measure, but it’s been a few years since I delved into reading about them.

As I wrote earlier in the thread, before it got dredged up again recently, the simple method that AKG used was to ping the capsule diaphragm with a small bead. You can also flick the edge mount of a capsule and usually hear the pitch.

 

[soliloqueen]

Not super relevant to the omni discussion, but going back some posts…

There is info about these Neumann testers on one of the historical audio gear sites that’s mainly in German. Forgetting the name of the site at the moment but there is info out there.

I thought it was capacitance over frequency that these measure, but it’s been a few years since I delved into reading about them.

As I wrote earlier in the thread, before it got dredged up again recently, the simple method that AKG used was to ping the capsule diaphragm with a small bead. You can also flick the edge mount of a capsule and usually hear the pitch.

you can measure the FR of a capsule electrically this way. I think someone did it here:
https://www.beis.de/Elektronik/CM2/CM2.html

 

[Biula]

There is, but I can't remember it. It's purely electrical. Is it impedance over frequency? Capacitance over frequency? I earnestly can't remember. There is some way to do it. I just haven't been able to find the paper on it in a long time.

Is impedance curve under a sweep frequency pressure field (e.g. a speaker in front of the capsule in an anechoic chamber)...

 

[soliloqueen]

Is impedance curve under a sweep frequency pressure field (e.g. a speaker in front of the capsule in an anechoic chamber)...

I said electrically. There is a way to measure the tuning of a capsule purely electrically IE no external acoustic pressure. It doesn't correspond meaingfully to the acoustic response of the capsule, but it's a fun experiment and tells you interesting things about the construction of the capsule. Obviously, you can take way more practical, useful and meaningful measurements by using external acoustic pressure like you describe, but where's the fun in that?