I have an Ashdown ABM 500 Evo 210 combo that is giving me a sound that sounds painfully like a blown speaker. This amp has never been gigged and when I began to turn it up beyond 25% of its power for the first time in a jam session, I started hearing the noise. I couldnt even drown out the 1X12 trace elliot 'tramp' combo the guitarist was playing before the speakers sounded like they could no longer handle the volume I estimate that at half of its capacity, there are popping or possibly thrown cone noises during low notes. My lowest note on my bass is an 'E', not a 'B'. I have tried all the variations between pre-amp and output levels to see if there are any differences, and there seem to be no discernable differences when the noise occurs, which seems to be at around half of its capacity. If I cut the bass, I can turn it up louder. If I put in more neck pickup and more bass, the 'thud' comes in earlier. Please help me diagnose this problem.