audio system cuts out when turned up

Hey all just after a bit of help.

I have a 1985 Mazda 626, i know old, and crappy, but i am a student, and i have to do with it for now. I have for a while had installed a cd head unit, a set of 6.5" speakes in the front, as well as a set of 6.5s in the back, also have a 700 watt amp powering 2 12" subs. now the problem is when i turn the deck up to a certain point, it restarts, i figure this could be due to not enough power, but am after a few opinions. Could capacitor help stop this? any suggestions i would be greatful for. O and what can i say about having a good sound system in my crappy car, other than i like my music.

amp could be overheating, headunit could be overheating, lots of possibilities

Does everything cut out? Just the subs? When you say it restarts, are you saying it starts back at the beginning of the song or it just cuts out and then comes back?

when i say that it cuts out i mean the whole audio system (head unit, amp, whole lot. when i say it restarts i mean that the head unit turns off and then back on. It only does this when i turn it up past a certain point. however come to think of it, it also cuts out when the cooling fan kicks in (that is when the head unit is turned up to a certain point). As i say i think that maybe i am draining to much power. But i am very thankful for any input. I am after a cheap, or even just suggestions as to what i can do to fix this problem. Thankyou

I would check both your battery and your alternator; Im not really sure, but I want to say that the 626 has quite a small battery, and I'm sure that the alternator probably can't handle running the headunit and the amp especially. You may want to look into getting a higher-amp alternator first off, and then maybe a more powerful battery (If you even have a place for one under the hood)

Ok, thenks for that. That what pretty much well what i had in mind, but didnt wana go spend heaps of money to have the same problem. i am sure that if i dont have enough room for a bigger battery then meybe with a hacksaw u could make some. lol