Have I damaged my amp?


Hi,
I have a Music Angel 300B amp which has been fine for sometime now. A friend visited to hear the new single driver speaker cabinets I've made, to compare these with my previous Kef's (the amp had been on for hours) I unplugged the Rt channel only and we had a listen for 30secs or so then I swapped back, the amp was still on. A few days later it started making loud rustling sounds 'under' the music (not volume dependent) on the right channel with some squeal when I tap the chassis, there is also quite a lot of noise when I power down from the Rt channel. I have tried swapping the valves with no change and have checked inside for loose connections 'bulging' capacitors etc and can see nothing wrong. So is this a probable cause for damage and what could it be? the problem is becoming noisier but only starts after the amp has warmed up an hour or more. My first thought is to replace the main capacitors under the transformer. I don't have a schematic for it but does anyone have any views on this.

Thanks,
Iain
irbow

Showing 3 responses by irbow

I did try gently tapping the 300B's with a pencil and they were silent. The 6SL7's were microphonic, could it be that both of them are dodgy, they're the original Chinese ones and didn't look very new out of the box.

Iain
Thank's for the replies,

I turned the volume down and then swapped the speaker, I wasn't thinking. I'm currently using another amp because it's not enjoyable waiting for the noise to start, as I said I have tried swapping the valves one by one (with the amp off and cooled down ;) and the noise stays in the right channel which is why I'm puzzled (I wouldn't have posted if it had followed a valve). At switch off it's loud more tearing than rustling.

Iain
Well, thanks for the responses, I guess I should take it to a repairer. I'm Ok with a soldering iron but I would need to know where to start.

Iain