tube problem/ crackle noise?

[Dvir]

Hello,
first of all, i am a JMD501 owner, i purposely write my topic here to get answer from a all tube marshall owners.
so here we go guys, i have a problem with my amp that every time after a while (about 5 minutes, sometimes less) i am starting to hear a crackle noise/ wind noise out of the amp. sometimes it cause the sound go lower and then rise again. i did post it in the JMD forum they said that it's a tube problem. so i am asking you if you have ever heard of it or had an experience with that problem? thanks.

[Laars]

Hello,
first of all, i am a JMD501 owner, i purposely write my topic here to get answer from a all tube marshall owners.
so here we go guys, i have a problem with my amp that every time after a while (about 5 minutes, sometimes less) i am starting to hear a crackle noise/ wind noise out of the amp. sometimes it cause the sound go lower and then rise again. i did post it in the JMD forum they said that it's a tube problem. so i am asking you if you have ever heard of it or had an experience with that problem? thanks.

OOPs.......... looks like I walked into that one....... Didn't notice it said JMD, not JMP.....

Sorry about that.

[surfnorthwest]

The JMD does not have a V1, only a phase inverter preamp tube. I don't suspect that tube is at issue. You are going to have to change out the two power and see if that corrects the problem, I suspect it will. Be sure to set the bias after changing the tubes.