yes, it probably is the sub. when running optimum power on a sub when it is new, it will have a "clapping/humming" sound. dont worry, ur sub is fine. just dont bang it really hard for a couple of weeks (2). after that it will have a muffled sound so then u can gradually turn it up more and more til u reach desired music level....and yes keep ur head away from the sub when listening to it, u will hear some noise.