Neumann K87 and K67 capsule capacitance

[soliloqueen]

I wouldn't worry about this so much. Your capsules sound and measure correctly and that is the important thing.

I don't disagree with you! as long as there is consistency i'm not bothered, but i am quite curious.

With how hard the diaphragm assembly is pinned down by the screws, it's difficult to believe material would make a huge difference.

 

[Tim Campbell]

My experience with K67 capsules including my own is that the tuning frequeny is directly related to the capacitance. If you are going to increase the capacitance you must lower the polarization voltage or raise the tuning frequency or they will collapse.

 

[soliloqueen]

My experience with K67 capsules including my own is that the tuning frequeny is directly related to the capacitance. If you are going to increase the capacitance you must lower the polarization voltage or raise the tuning frequency or they will collapse.

yeah! i've seen cheap chinese capsules that show up as 80 or even 90 on my setup (so 65-75 on yours maybe?) and my assumption is those must be tuned insanely high.

 

[GeorgeToledo]

That would make sense. The U89 capsule is edge terminated and higher capacitance.

I’d been thinking that but the reason I did speculate “unlikely” is that the drawing is already labelled U67. But on second thought it could be a vestige of something earlier, so it could still be related to that.

Thiersch has put a new diaphragm on the purported early edge terminated U60 capsule, but there isn’t much detail out there. It had once come up for sale on the Neumann forum ages ago. More recently on Reverb, with Thiersch refurb on the capsule.

 

[soliloqueen]

I DID end up re-testing this. On a better cap meter the k67 samples I have test 55-62, and two of my capsules 59 and 61.

 

[Gus]

A question for the posters in the thread, do you test with the charge voltage applied to the capsule?

 

[Tim Campbell]

A question for the posters in the thread, do you test with the charge voltage applied to the capsule?

No. I measure just the capsule. The capacitance while polarized can vary by the strength of the polarization voltage if the membrane is tuned low.