Please help me!!

Lucas, You were right, the very first thing to look at would be to put in a new tube.

 

You could eliminate theories 2 and 3 above by playing through the headphone jack and using another cable for an extended time.

 

$10 it's the preamp tube.

 

I'd try a new instrument cable first- I wasn't going to say anything, since I know absolutely nothing about SWR redheads, but I'd think swapping the cable first would be a heck of a lot easier than the tube.

 

I don't know, but usually it's a simple matter. Consult your manual or look it up at swr.com.

And yes, it would be consistent if it was the speaker. What you're hearing sounds like a dying tube.

 

You would hear crackling even if you weren't playing anything if it was the cable.

 

I don't move around much when I'm not playing anything, but whatever, man. Just trying to suggest the simpler fix first.

 

I know this is an old post but I thought I would reply for anyone else having this problem. I took my amp down to my repair guy and and he said he replaced out all the hard solder. Said it was cheaply done at the factory and a flaw in the design. When the speaker vibrates the cab the old hard solders gradually weaken and ground out causing the very bad crackling noise. I'm now electronic wiz, but this is what he told me. Anyway it's fixed now.