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[klaus]

No, it does not make sense. A red dot next to the serial number identified the padded U87 version until the early 1970s, thereafter the dot was changed to light blue. (I'd call it turquoise)

[afterlifestudios]

Thanks Klaus. Yes, it seemed out of sequence to me too.  Yet, here they are.   (It may be the same color/lacquer that was used on the mounting screw on the switch assembly from previous post.)
Lower serial mic with “turquoise” dot. (930-20 circuit)
Higher serial mic with red dot. (930-21 circuit)

[klaus]

The blue dot does not look stock. Sloppy paintwork is not a hallmark of Neumann, also, the color is not right.

[afterlifestudios]

Thank you Klaus.  Agreed.  Sloppy paintwork is not a hallmark of yours either, but would this (like the mounting screw paint on the switch assembly) be something you may have done after working on it? Maybe impedance strapping change?

[Derek Samuel Reese]

Seeing this thread made me want to take a peek at my “pair” of old (non “a”) U87’s capsules.
One head assembly has the “kk 87 a” badge with serial number as expected, and the capsule looks good.  The other U87 has no badge on the head assembly, but a serial number baked into the plastic.  It also has epoxy over one of the fastening screw holes, leading me to believe it’s never been opened.  Not feeling like I should open it just out of curiosity?  (It sounds great!).
Any info to be learned from what’s visible?

What does these numbers represent ? i zoomed in but can't read the numbers ?
Im assuming these are the baked in the plastic numbers you mentioned ?
I also have a series of numbers on my u67 in the same place.

[afterlifestudios]

What does these numbers represent ? i zoomed in but can't read the numbers ?
Im assuming these are the baked in the plastic numbers you mentioned ?
I also have a series of numbers on my u67 in the same place.

This is the serial number of head assembly I believe.  Later moved to a badge like in the other photo.  (Klaus please correct me if wrong?)

[Derek Samuel Reese]

so a serial number of the head assembly doesn't have anything to do with the serial number on the bottom of the mic ? Then there must be another group of numbers somewhere that can date the head assembly ?
That would be cool.

[afterlifestudios]

so a serial number of the head assembly doesn't have anything to do with the serial number on the bottom of the mic ? Then there must be another group of numbers somewhere that can date the head assembly ?
That would be cool.

Again, Klaus will be able to verify, but in my efforts to date mics with Neumann, they replied that they have no dates for serials of heads.  Only for "bodies".

[Derek Samuel Reese]

Again, Klaus will be able to verify, but in my efforts to date mics with Neumann, they replied that they have no dates for serials of heads.  Only for "bodies".

This is interesting, why even put numbers on something if a record won't be kept.
I also wondered about the serial number on my psu ?
it happens to be a lower number than on my u67, but if the mic's serial number has nothing to do with the psu serial number than we will never know lol
im gonna go have a bowl of cereal now.

[klaus]

Numbering mics, power supply and other relevant parts like head assemblies is done to:

1. record design changes and when they happened, which will also be noted on internal schematics (note in most schematics it will say "starting with serial number XXXX" or a letter suffix indicating major changes in heads)

2. to trace sales and connect each to a specific item- when it was sold, and where it went, and how much it sold for

Neumann's power supply numbers are usually higher than the corresponding mics they came with: spare units, loss, theft, damage, raised the numbers. It is very rare to have a number match between mic and p.s.

[David Satz]

There's always some detailed information that gets generated during production as a microphone manufacturer measures and tracks the characteristics of "sensitive" components, e.g. sorting a large batch of semiconductors or capacitors according to their exact, measured values into some number of bins. But by the time assembly and testing are complete, the characteristics of those components have been adequately balanced by other interrelated selections.

There's no necessary reason for a manufacturer to code such parts in a way that's transparent to the general public, or even to archive that information for themselves in many cases. Eventually such information loses its reliability anyway as those components age, or because of repairs that the factory knows nothing about.

Some people even choose to modify their microphones, or so I've heard; that may be fake news, though ...

--best regards

[klaus]

Completely fake news.

[afterlifestudios]

Is it known when the first non “dome shaped” base for the k67/870 capsule was introduced?  (The flat-topped one sits 6mm higher.)
.

[gtoledo3]

You can safely assume that, originally in 1973, a 1973 K67 will sound exactly like a K87 would have sounded of that same build era. But time may have done all kinds of numbers on diaphragms and other parts of the mic, (contrary to speculation, diaphragm tension is not among them).

Klaus, interestingly, in this thread you explain how you find capsules losing tension over time:

“Exactly what wears out?

Diaphragm tension becomes lower, affecting the diaphragm’s
uniformity of movement...”

Anyway, in this thread you also state that Neumann denies that, but fwiw, Neumann had and has stated that is a service issue, outside of whatever max SPL handling is.

http://forums.musicplayer.com/ubbthreads.php/topics/476943/question-for-klaus#Post476943

It’s certainly everyone’s prerogative to be able to change their mind, it just seems that the Klaus of yesteryear comes closer to agreeing with me than the current model. :-) Hope you’re having a good day!

[Derek Samuel Reese]

I would love to know what the two letters and two numbers represent on an original u67 brass capsule ?
maybe the letters were the initials of the person testing the capsule ? but the numbers ? I'm just guessing lol
I realize that the brass capsule's were produced from 1961-1964 but I kinds of stinks that you don't know if you bought a 1961 or 1963 brass capsule, so each capsule is within a four year mystery ?