3000gt

So i just hooked up my stereo system in my car and i took it out of my other truck a month back, and it never had this problem since i owned it all, the only thing different is the headunit is a sony CDX-S2010.

So basicaly the issue im having is that when i turn the gain up while a song is playing or almost everytime i turn the gain up unless the stereo is off first the sub will sudenly start banging harder like to hard and its not even to the beat of the song and it will do it on any volume. Another thing is i can move the gain all the way up to about the half way mark and it doesnt have the issue ever but past that usually is when it goes nto pshyco mode, but if i turn the system on with it already set to like full gain or anywhere then its okay unless messed with then i can only tun it lower or it will act up.
I also have 3 subwoofers but havent tried messing with the other two yet to see if they do it but im sure they will also.

Sonic

iTrader: (1)

Probably have a bad gain **** and/or clipping the sub which is probably to the change in hu.

luke99

could be several factors , loose wiring inside the box , a bad ground can cause issues at higher vollumes , but from the sounds of things its a loose wire or clipping from the amp being maxed out i you have the subs being underpowerd your going to see this problem