Before you can check anything, you need to find the number. Neumann serial numbers are not always in the same place.
Pro Tip: If the serial number is printed on a cheap sticker that can peel off, be suspicious. Authentic Neumanns use permanently engraved or etched numbers.
During this period, Neumann assigned different number blocks to different models.
⚠️ Warning: Many counterfeit mics have plausible-looking numbers. Always cross-check with construction details (capsule type, PCB color, transformer markings).