So, just last week i installed an aftermarket head unit (Sony MEX-BT3800U nothing amazing but it does for me) and 2 new vibe slick 5x9 front door speakers.

Everything is working fine apart from one thing, the 3 amp fuse in the cars fuse box keeps blowing everytime i turn the volume up loud. In my haynes manual the 3 amp fuse is the " instrument cluster, radio, navigation, DVD player"

When i installed the head unit i didnt buy the wiring adaptor, i just soldered and heat shrinked all the wires myself. Ive checked if there is any loose wire sticking out but theres nothing, so its cant be shorting (i dont think).

I was thinking it could be:-
-higher in car fuse (maybe a 4 rather than a 3)
-speakers on the wrong way (p-p, p-n, n-n or whatever)

Any other suggestions guys?