Terrible, ear-splitting static

[Dankology]

The rehearsal room is being readied for action again...

We've got a couple of Mackie (or possibly Tapco) Thumps that haven't been used in anger for some considerable time - active speakers fed from a Behringer XR18. When I was giving everything a test run last week one of them gave a little crackle which very quickly built up to a quite terrifying loud static sort of noise - pulled the plug but exactly the same thing happened a few minutes after plugging in again. It's a very electrical sounding noise, if that makes sense.

Any thoughts on how to bottom this out? I was wondering about possible condensation inside or maybe a a dodgy solder joint that starts playing up as things get warmer?

[itu]

Is every piece of equipment in the same phase (230 VAC)? Sure a cold solder joint is possible, although they can be complicated to find. How about loose cables, screws or broken PCBAs?

[Dankology]

The electrics *should* be sound - it's a small room in a domestic property that was recently refitted and rewired by the owner's (professional) electrician friend - although stranger things have happened, I I suppose. 

The cables are ok in as much as the speaker misbehaved even with different xlrs and kettle leads.

I'll have to figure out how much a replacement will cost vs my time poking at it with a screwdriver. Thank you for the pointers!

[Dan Dare]

As it's only one of the cabs that makes the noise, that would rule out mains issues. By "static" noise,, I take it you mean a kind of hissing roar. I had a similar experience once with an amp. It turned out to be a capacitor that had failed. Resist the temptation to poke around and take it to a repairer is my suggestion.

[Dankology]

It sounded more like being in a tent that someone was whipping increasingly quickly and forcefully... I think I've got a recording of it that I'll try to post.

But you're right - if it isn't as obvious as a visibly disconnected component, I'll be out of my depth.