Slight cracle from one channel of Jolida SJ302a

Two areas, and sometimes both are involved. A bad tube. You can try changing left and right channel tubes. The other possible problem (and "crackle" sounds like this could very well be it) would be a capacitor going bad. That one is a little trickier to trouble shoot, and not being very familiar with that particular amp I wouldn't know where to tell you to start looking. Sometimes, it's a combination of the two, which can make trouble shooting very difficult.

I had a 302a a few years back... It developed a slight, intermittent crackling sound and, a few days later, the fuse blew out. Changed it out, and it played beautifully after that.

I'd check the tubes first, that's most likely the culprit... but, fuses are less than a buck, so if it's not the tubes, you might try replacing the fuse in the back.

Enjoy the amp... it's a fantastic piece of equipment.

Best,
Eric

I own several Jolida's. When you change the tubes try cleaning the tube sockets with some good contact cleaner. I've had crackling show up on retubing and cleaning the sockets fixed it.