The only time I hear that quickly rising sound from the subs is when someone has added the sub amp to a factory system and not installed a remote turn on adapter (signal maker) but just jumped the amp power to the remote connection. They then forget to leave the radio on (or buddy/girfriend/etc) then the amp has no signal but is on and just ramps up until it blows (usually breaks the voice coil on the subs though). Do you have a correctly wired amp remote turn on signal from the head unit?