R/E/P > Klaus Heyne's Mic Lab

Neumann U47fet Reissue: Complete Tear Down and Analysis

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Ernie Black:
Connector Plate
Aside of using a Neutrik, rather than Switchcraft 3-pin XLR, all seems the same as before.
Note the serial number of one of the first units shipped: 10106. I.e. most likely the pre-series went to <10100 or so, and they started shipping with ser. no. 10100 to customers last week.

Ernie Black:
Head Connectors
Note the close resemblence of the new part to the old. We are starting at ca. 10.000 with the re-issue, (the head plate serial number always used to hover around the serial number of the mic).
The U47fet reissue most likely started at 10.100.

Ernie Black:
Bottom Board
Point-to-point, as always; no chips or multipoint wire connectors to be found anywhere

Ernie Black:
Amp Guts.
According to Neumann's Schneider, the model they chose to duplicate 1:1 for physical circuit layout was from ca. 1972- Circuit #02. While the electrical circuit and physical features of the mic resemble that of the #06 variety (last version with three switches. Two remaining versions, #07, #08 did away with the -6dB switch, and had the transformer output strapping permanently set for 200Ω, i.e. secondaries connected in series).

Notice the same point-to point mess that has tripped up countless repair people over the years. The version after 1974 at least had a board which you could slide forward for better access to most of the amp components (see vertical edge of the gray sub-board, with T2 (BC212) showing horizontally). Until 1974, as in the reissue, every time you want to work on the mic amp, you have to do micro-surgery in situ, due to the lack of a circuit board that can slide out.

Note hexagonal column-construction of the amp compartment of the reissue, same as the original through 1974; whereas plastic injection molding was used after 1974 to form the amp cavity (the original in all pictures is a 1975 model). The plastic mold allowed for a slot to insert a newly developed rectangular circuit board, which made component layout and servicing a bit easier.

It's kind of amazing that Neumann would succumb to such unorderly component layout, but kind of cool that they have no shame doing it, for the sake of keeping it all original and immune from criticism by "100% authentic"-freaks, damn the preconception of German anal-retentiveness.

Ernie Black:
Transformer Side
Note transformer core lamination differences. This could just be the appearance of the cutting edges of each laminate, or it could be a different alloy. Winding resistance seems similar to the old one, ± 10%. In any case, it does not seem to matter- the tone of the new mic retains its original characteristics.

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