Right, so I've had this old Peavey Century 200 (4ohm) head sitting around for AGES, finally the other day I decided to give it some company by purchasing a TC Electronic 2x10 (8ohm) cab.
Because the Peavy is 6,000 years old and the cab is pretty modern, they both have different connection plugs (Peavey is standard 6.5mm jack output while the cab is Speakon input).
So I buy the right cable to connect them, turn on the power and everything seems ok. A short while later however I start getting this almighty thudding sound, like a heartbeat on steroids. It doesn't matter which dials I turn on the amp, even with everything dialled off, I still get the thudding sound. I look at the speakers and they're about to jump out of the cab.
Here's the weird part though, when I tilt the head 45 degrees, the thudding stops completely and everything functions as it should. I should also mention there is quite a lot of heat, I'm sensing this is a bad thing as I've never had an amp kick out so much heat.
I'm hoping someone can help me understand what's going on before I ultimately burn down my house.