Mesa Mark IIB crackling/buzzing noise

[TheDosss]

Hey guys lately I have been noticing my amp makes a loud crackling noise when I let chords ring out. I have no idea what it is or how to fix it so if anyone has any idea please let me know. I have uploaded a couple recordings of the noise.

https://soundcloud.com/jason-fados/mesaampbuzz1
https://soundcloud.com/jason-fados/mesaampbuzz2

 

[Don]

Sounds like it could be screen grid resistors. They're the 470 ohm/2 watt resistors connected to the power tube screen grids.

 

[user 37328]

I had a similar problem when I first bought my Mark II-B. It turned out to be old/dirty preamp tubes. Have you tried replacing them? They're relatively cheap.