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[Gnas]

If I purchased a U47Fet Collector's Edition mic. Would I be able to use the mic's capsule in a U47 with all 3 polar patterns?

[klaus]

... only if he rear side diaphragm is sputtered with gold, which some are, some are not.

[RuudNL]

I once read that Neumann used capsules for the U47 fet that were not completely within specification on one side.
(Of course this isn't a problem, as the U47 fet is cardioid only.)
Do you know if this is a true story?

[David Satz]

Hmm, I don't think that's exactly right, though there's a slight ambiguity in what Martin Schneider said about this in the two "Pinboard" messages that I have notes about where this question came up. The basics are:

- "Acoustically / mechanically all the capsules are absolutely identical." [Meaning K 47, K 49, K 47fet, K 47/49, or whatever it's called in a given time period]

- "In older days" the K 49 capsules for the M 49 and (later) U 48 had tighter front/back tolerances than K 47 capsules for the U 47, or more precisely "[t]he most symmetrical capsules were named K49. Thus, the capsules with slightly looser tolerance were named K47 (for the U47)."

At some point before the time of his postings, the tolerances for the "one-sided" capsules were brought into line such that the front/back limits became the same--and after that, the only difference was the number of wires. (Well, there was also a name change to "K47fet" for the capsules with no rear contact wire.)

What isn't exactly clear from his first posting is whether this tightening of tolerances occurred before the U 47fet was introduced or not. But the second message says that "Since 1960 the specs have remained the same for the above capsules", so that probably means "before"--in which case the tolerances for the U 47fet's capsules would have been the same as those for the other capsules of this series.

--best regards

[klaus]

(...)
What isn't exactly clear from his first posting is whether this tightening of tolerances occurred before the U 47fet was introduced or not. But the second message says that "Since 1960 the specs have remained the same for the above capsules", so that probably means "before"--in which case the tolerances for the U 47fet's capsules would have been the same as those for the other capsules of this series.

There was a "0 Degree"(i.e. front side) designation printed on each K49 capsule box made between 1959 and 1965, to indicate the side which adhered closer to the ideal spec (i.e. noticeably better than the ±2dB tolerance set for the design) as frontside, as that is the primary side in the M49.

To my knowledge, the U48 with K47 did not receive the frontside-selected K49 capsules. This all stopped anyway, after 1965 and the introduction of plastic diaphragm rings on all LD Neumann capsules.

When I order(ed) K47, K49, or fet47 capsules with two sputtered sides, I have found that designations between the three types as well as front sides were randomly designated. I.e. no discernible performance differences between capsule type and capsule sides, outside of the ±2 dB spec could be measured or heard.

Therefore I always ordered the cheapest version Neumann would offer in a given time period (which, by the way, also changed several times, supporting the argument that all these designations were pretty much made arbitrarily, merely dictated by marketing or available stock.

[gtoledo3]

I have definitely seen more than one “K47fet” replacement part # 53223 come with a rear wire attached, though I don’t know if all of them have.

I have noticed a tendency for the K47fet replacement part 53223 in comparison to part 53291 (K49) to have a less perfectly aligned area of gold evaporation coating but that may have been luck of the draw.

The capsule which is installed in M147 and TLM49 seems to have a piece of clear “mylar” on the backside. I don’t know if early units had gold membrane on the back or not.

[Gnas]

Does the alignment of the diaphragm matter?
Also, could Klaus or somebody explain how to tell if a capsule has been reskinned or not? Thanks for the useful knowledge so far!

[RuudNL]

I have seen many U47 fet microphones with a double sided gold evaporated microphone capsule, with the membrane wire from the backside simply cut off.

[Kai]

If I purchased a U47Fet Collector's Edition mic. Would I be able to use the mic's capsule in a U47 with all 3 polar patterns?

Here‘s a photo of my own 2014 Neumann U47fet Collectors Edition Reissue, peaking through the wire meshes onto the back of the capsule.
You can see the back diaphragm is gold sputtered, the center screw is there, but no wire attached.

Would take a brave heart to mount a wire.

[RuudNL]

Would take a brave heart to mount a wire.

I did this many times. You need a steady hand and the right tools! You have to be careful not to wrinkle the membrane.