how can i fix the volume on my hp pavilion a 1710n?

i just bought a hp pavilion a 1710n 2 days everything works fine except my speakers are so low you can barely hear them. i have look at the control panel and the volume is all the way up i dont get it. i double check that its hook up in the right port and everything i even hook up new speakers that i know work on my other computers and its the same result. whats weird is that the head phone jack works just fine. how can i fix it.