Beyerdynamic M260 N(C) with extremely low output

[Seb Mo]

Does anyone know what would cause a Beyerdynamic m260 n(c) with the black handle to have an extremely low output and very limited frequency range? I also have a m260 n (with the blue-grey handle) which is much much louder and has full frequency response. Can a bad or loose ribbon cause this, and if not, what else might?

Thanks in advance for any help- I am a newbie to microphone repair and gave been lurking and searching through these forums a lot but I have hesitated to actually ask anything because I know I still have so much basic groundwork to cover and that there is so much good information already available here, but I’m at a dead end.

 

[OneRoomStudio]

https://repair.ulrigg.com/beyerdynamic-m260/

 

[Seb Mo]

Thanks OneRoomStudio, I am aware of Ulrigg and will reach out to them if it comes to it. From what I’ve read, a weak magnet on an m260 likely wouldn’t reduce output by more than a few dB, and I (perhaps incorrectly) would expect the ribbon to do absolutely nothing if it was broken, not just pass a very weak signal. Is this what you would expect from a stretched or loose ribbon? And if not, what else could cause this?

 

[OneRoomStudio]

I linked to that page because of the information there - he states:

“In many cases, there is debris in the magnetic gap, which can take the form of flaking glue, or sometimes metal contamination. In this example, flaking glue is preventing the ribbon from proper movement. Unfortunately, in most cases the ribbon needs to be replaced in order to properly clean.”

There’s a good chance that’s your issue.

 

[Seb Mo]

Thanks for the glue tip. I ended up taking off the wave guide and reseating the ribbon, which may have come loose or pinched off on one side, but it still has very low output with limited frequency response. There isn’t glue blocking anything, but the ribbon doesn’t appear to be crimped in any way, longitudinally or transversely, which leads me to suspect the ribbon is either stretched or non-original.
Could either of those ribbon states cause such extremely low output?

If glue had been the issue, I guess I could have tried the method I read in another thread of sweeping a tone through the mic using the ribbon as a speaker to loosen the glue, but alas, that doesn’t seem to be the problem.