M50 aluminum membranes

[Tim Campbell]

If anyone here has any technical info on Neumann aluminum M50 capsules please contact me.

 

[Murdock]

What exactly do you want to know?
I assume you saw the great "saturn-sound" website?

 

[Delta Sigma]

Ben did a run of M50 capsules. I assume he has some info. Pretty sure he did a couple versions too.

 

[k brown]

Ben did a run of M50 capsules. I assume he has some info. Pretty sure he did a couple versions too.

Later M50s were Mylar - did he do metal as well?

 

[Delta Sigma]

Don't think he produced any aluminum. Just thought he might've dug up info when producing his M50 capsules.

There's a thread somewhere here on it.

 

[Delta Sigma]

https://groupdiy.com/threads/feeler-k50-capsule-for-m50-mic.74813/

 

[k brown]

If anyone here has any technical info on Neumann aluminum M50 capsules please contact me.

I assume you've seen the Saturn Sound pages?
http://www.saturn-sound.com/Curio's/neumann's kk50 capsule assembly.htmhttp://www.saturn-sound.com/Curio's/neumann's kk50 - 2nd type k50 capsule.htm
Also, the aluminum M50 capsule was the same as that in the KM 53; might be a bit easier to obtain one of those for dissection.

 

[Tim Campbell]

Thanks guys. I have a very old M50 that needs a new diaphram. I just need to check the thickness of the aluminum and tuning freq, I have the old diaphram which is extremely thick so I just want to check that this is really correct and the tuning freq. so I can save some time

 

[k brown]

Thanks guys. I have a very old M50 that needs a new diaphram. I just need to check the thickness of the aluminum and tuning freq, I have the old diaphram which is extremely thick so I just want to check that this is really correct and the tuning freq. so I can save some time

BeezKneez did a copy of that capsule; here's their post about it:

 

[Tim Campbell]

Thanks K Brown. My capsule is from 1952 and the spacing between membrane and backplate is machined into the capsule. I have replaced it with mylar but it does not sound as good.

 

[k brown]

And some info from Klaus Heyne about how difficult those diaphragms were to tension:

 

[Murdock]

Thanks guys. I have a very old M50 that needs a new diaphram. I just need to check the thickness of the aluminum and tuning freq, I have the old diaphram which is extremely thick so I just want to check that this is really correct and the tuning freq. so I can save some time

Diaphragm thickness of the aluminium version is 8 micron. Tuning freq is probably as high as possible. I know that for the first version with pvc diaphragm the resonance frequency of the whole system was 15khz. But it also had a different frequency response than the later aluminium one.

 

[k brown]

FWIW, this post claims 0.7 micron, though they mis-identify it as nickel (there never was a nickel one).

 

[k brown]

I know Tim already knows this, but for others following the thread - though they share the same aluminum capsule, many sellers of KM 53 will say pop an APE on one and get virtually the same sound as an M50; I'm convinced that the biggest contributor to the sound on the M50 (and M49) - other than the capsules, obviously, is the particular, huge transformer used, which the KM 53 does not have; the AC701 contributing far less to the mics' sound. Decca were quite content to convert their M50s to FET, but would never have replaced that juicy transformer.

 

[k brown]

Thanks K Brown. My capsule is from 1952 and the spacing between membrane and backplate is machined into the capsule. I have replaced it with mylar but it does not sound as good.

Not surprising - as you can see on the Saturn Sound diagrams, the construction of the Mylar capsule was completely different from the one with the alum diaphragm, with also very different spacing.

 

[Murdock]

I know Tim already knows this, but for others following the thread - though they share the same aluminum capsule, many sellers of KM 53 will say pop an APE on one and get virtually the same sound as an M50; I'm convinced that the biggest contributor to the sound on the M50 (and M49) - other than the capsules, obviously, is the particular, huge transformer used, which the KM 53 does not have; the AC701 contributing far less to the mics' sound. Decca were quite content to convert their M50s to FET, but would never have replaced that juicy transformer.

Don’t forget the headbasket. And in the M50 the capsule is flush mounted in the sphere. The kk53 in the km53 has a gap between capsule and housing as far as I know.

 

[Tim Campbell]

Well I know that the nickel capsule was 0.8 micron but the aluminum diaphragm that came on my M50 capsule mounted on my MM2 measure a whopping 60microns thick which I cannot understand.

 

[k brown]

Hmmm . . . plus that image doesn't look like any of an actual M50 capsule that I've ever seen; including the post, which is supposed to be 2-pc rubber; no part of it was that long, or solid metal as that appears to be. Almost seems like the entire capsule was replaced with one from a measurement mic.

 

[Tim Campbell]

K Brown this is the earliest version of the M50 capsule. Neumann produced it from 1948 -52. This is a Neumann MM2 microphone built for anechoic chambers. Only 90 of them were ever built. Mine is no.50

 

[Barry Hufker]

I know Tim already knows this, but for others following the thread - though they share the same aluminum capsule, many sellers of KM 53 will say pop an APE on one and get virtually the same sound as an M50; I'm convinced that the biggest contributor to the sound on the M50 (and M49) - other than the capsules, obviously, is the particular, huge transformer used, which the KM 53 does not have; the AC701 contributing far less to the mics' sound. Decca were quite content to convert their M50s to FET, but would never have replaced that juicy transformer.

@k brown, which transformer is in the M50?