Amp buzzing made worse when I use my tone knob

Different amps?

 

Grill rattle ?

 

Does not seem like a speaker issue.

I would say it's a bass issue, but you said other basses do the same thing?

That leaves the amp. The crackling knob is definitely the amp.

 

That's just the nature of the J bass, man. You could get hum canceling pickups or check the grounding, but that is not the amp or cab.

Edit: just heard the crackling of the amp's knob. It could be the amp. My money is on the bass though.

 

+1. I think the mid knob could use a TINY bit of de-oxit, but it's unrelated to the buzz. You might want to poke around in the pick up & electronics section.

 

If it happens with multiple basses, it's your amplifier (not bass or speaker). Is the amp properly grounded? Does the buzz happen when on different outlets? Have you tried it outside your home in a different location? Buzzing from an amp can happen due to electrical issues (or by having dimmers or certain types of lights on the same circuit) or it may need servicing.

 

What were the other basses you tried it with ? If they were single coil pickups it does not matter who made them they have some hum to them . And even more when you are facing the amp.

 

It's not the speaker, a speaker only reproduces the signal sent to it. I'd say it's the bass, since it changes with the position of the tone knob, but if it happens with different basses then it's most likely your house. Something may be radiating EMI and/or RFI.