Brüel & Kjær 1" lab microphone differences

[FrodeM]

Recently I have tried to look into this, but not found any good answer.

The first set of Brüel & Kjær 1" laberatory microphone capsules were the 4131/4132 types. These are the free-field and pressure-field versions of practically the same mic, similar to how the 4133/4134 1/2" mics are related and the 4135/4136 1/4" mics are.

Later on, they would produce the 4144/4145 pair of 1" lab mics, a pair that immediately replaced the 4131 and 4132. The problem here is that it's clear they did something, but there are no mention in any manual what they did. As soon the new version was out, it's almost as if the old version never existed according to the literature. The 1/2“ and 1/4" versions did for reference not change at the time, on the other hand.

So I will ask, do any of you have any idea of what may have changed for the 1" mics, and why?

[Bryn]

While the microphones somewhat look the same, the newer models are actually optimised for certain things, with the 4144 model for pressure-field measurements and the 4145 for free-field and sound pressure measurements. Should also note that the 4144 model can take measurements within a wider frequency range between 2.6 Hz to 8 kHz.

[1audio]

Sorry I missed this. The 4131 and 4145 are virtually identical. Same for 4132 and 4144. The differences are probably internal materials and maybe a better way to stabilize the diaphragm over time. And possibly repairability. Early on they offered repair but it changed around then and you get a small discount on a new one with returning a broken capsule.