My Vibrolux has been making this noise. It starts out being the standard hum of the amp when its engaged, but starts getting crackily and the hum gets louder and louder until it culminates with a loud popping noise and the hum temporarily subsides to normal levels and then it starts all over again. The sound is similar to when one of your blackberry or iphone friends gets a text message around the amp, but its louder and like I said culminate with the loud pop.
The tubes are around a year old to my knowledge and I play it all the time.
I have tried plugging it into different outlets and surge protectors to no avail.
It makes the noise with or with a guitar plugged in.
I have searched the forum and haven't seen something that hit this right on the head.
Any help would be greatly appreciated!!!