We built a portable stereo using 40mm square tube welded as a skeleton structure 1.4 m x .5m x .5m , surrounded it with MDF , tappered at the front ,
lots of breathing holes in the bottom to allow battery gases to escape .
Put a hinged lid on it to access the components which we kept purely 12 V so we could use a deep cycle battery 140 A/H Marine battery , Kicker 12 inch in box subwoofer fitted flush into MDF box ,
2 kicker 6x9s , kicker 360w 4 channel amp and finally sony headunit which was mount at rear of box for protection ,
We have taken it to gymnastics / parkour / tricking get togethers at the beach and parks .
When we first fired it up we could not believe how loud it cranks running off an i-phone, i have been surfing out the back 300m away and could hear music still , quality is amazing battery lasts for about 7 hrs at full tilt , weight was the only enemy at 55kgs , takes two blokes to lift it or sack truck , but well worth it in the end .
Have photos if your interested . GL with yours