I picked up this used Vox AC15 on the promise that the owner had changed the tubes. Well he did, sort of and well. I factored in the cost of new tubes. I've owned dozens of Vox's of all kinds now and they've all needed NEW TUBES. The factory tubes are junk and seem to rattle sooner or later. I love these amps otherwise, but the tubes??? Garbage. But otherwise a bitchin amp.