Having an issue with my swr sm 500 bass amp or possibly my speaker cab, I noticed as I was setting up my gear for a gig last Friday evening the speaker cab, which is an swr 4 x 10 Goliath 3 cab, started to fart and splutter a bit when I played my Bass. At first I thought it may be the central tweeter on the speaker cab, but after 5 mins it cleared and seemed ok again, I turned my amp off to finish setting up, then turned it on again and the same thing happened, i’m glad to say that it was ok for the gig and I didn’t notice any distortion or spluttering coming from the cab. I’m thinking maybe an amp problem, possibly a valve, the amp has a preamp valve in it, would a dodgy valve cause this sort of problem? Or maybe something more serious in the amp or even maybe the central tweeter on the cab? Anyone else experienced similar? Thanks in advance!