My new amp came yesterday and it seems pretty sweet although i havent got the chance to crank it yet. It's a Carvin MTS 3212. 100 watts, all tube, 2x12 combo. Anyways, at certain frequencies, the reverb tank seems to be vibrating and making an unpleasant rattle. Any ideas from you tech guys (yea u know who u are!)? Any help would be much appreciated. thanks.