FIX: Neumann KMS 105

My wife Katie Nelson and I both use Neumann KMS 105 condenser microphones for live performance. We love how the microphones sound and trust the Neumann brand.

The Problem

Recently Katie’s microphone was passing audio inconsistently. Sometimes it was normal, sometimes the output volume was quieter, and sometimes it would crackle as if the XLR cable was bad.

I called Sennheiser, the parent company of Neumann, to inquire about repairs. They connected me directly with a bench technician who kindly asked questions about the symptoms and then walked me through the fix. He correctly suspected that the hex screws holding the capsule to the internal printed circuit board (PCB) were loose. In fact, the capsule was completely disconnected from the PCB. I was surprised that the microphone worked at all considering there was almost no contact between the capsule and PCB.

The Fix

1. Take out the machine screw on the side of the microphone that holds the XLR insert in place. There may be a small lock washer underneath the screw. Set them aside.
2. Unscrew the basket (or grille, as people often refer to it).
3. Slide off the black capsule cover screen.
4. Very carefully pull on the capsule while simultaneously pushing on the XLR insert. WARNING: BE VERY CAREFUL WITH THIS STEP. THE PCB HAS A SERIES OF WAVY CUTS IN IT. TOO MUCH PUSHING OR PULLING CAN BREAK THE PCB. GO SLOW. GO EASY.
5. Pull back the rubber ring around the brass capsule body. Remember the orientation of the ring in reference to the notch in the body.
6. Confirm that spring is seated properly on the capsule center pin.
7. Push the capsule body onto the PCB until fully seated. The hex screws should be positioned over the solder-tinned holes.
8. While holding the capsule and PCB together in that position, use a 0.035″ (0.89mm) hex key to tighten down the tiny set screws.
9. Replace the rubber ring. Make sure the orientation of the ring fits into the notch in the body.
10. Carefully insert the assembly back into the body. Again, be very careful. You will likely need small pliers/grips/etc. to pull the XLR insert all the way into position while simultaneously pushing the capsule into the body.
11. Tighten the screw through the body into the XLR insert.
12. Slide the capsule cover screen onto the capsule.
13. Screw the basket onto the body.
14. Test the microphone. If you still are experiencing audio problems, contact Sennheiser for service.

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