CMV563 noise

[weatherbox]

I bought a CMV a while back that's got a bit of a noise problem. It arrived fairly quiet and nice; within a week it was screaming static. I replaced the PSU with a Drefahl unit + cables, which helped a lot (it was unusable before.) It's still got more low frequency-centered hum than I'd use for anything less-than-raging, volumewise - too prominent for acoustic guitars and vocals. I bought a replacement tube which turned out to be unusable. It's got a Telefunken ec92 in it now, though my experience with bad tubes has generally been more broadband in annoyance. Grounding appears to be ok.
I'm kinda leaning towards transformer as the culprit based on absolutely zero experience. Does the following freq chart point to anything to more knowledgeable eyes?

[hogfish]

How old is the mic and when was it last serviced? EC92 is the stock tube for that mic. There should be a 5 uf cap connected to the plate of the Tube. Do you know if that capacitor is failing? If you bought the mic blind, I would find a good mic tek to look at it or send it to Gefell, who services those CMV mics. Neumann will refer those mics to Gefell if you send it to them......

[Nick Sevilla]

Hi,

It is not the power supply, nor is it the tube. It is probably a filtering capacitor (they have some in there)...

You should try to take it to a reputable mic tech. Where do you live?

As to using Geffel / Neumann, there are mixed reviews, as they sometimes might replace stuff that does not need replacing necessarily... caveat emptor.

Cheers

[joel hamilton]

I bought a CMV a while back that's got a bit of a noise problem. It arrived fairly quiet and nice; within a week it was screaming static. I replaced the PSU with a Drefahl unit + cables, which helped a lot (it was unusable before.) It's still got more low frequency-centered hum than I'd use for anything less-than-raging, volumewise - too prominent for acoustic guitars and vocals. I bought a replacement tube which turned out to be unusable. It's got a Telefunken ec92 in it now, though my experience with bad tubes has generally been more broadband in annoyance. Grounding appears to be ok.
I'm kinda leaning towards transformer as the culprit based on absolutely zero experience. Does the following freq chart point to anything to more knowledgeable eyes?

one of Mine just started doing this. its time for a recap.