help me plz

[sonnyandersonrx3]

i have 2 12s hooked to a 800 watt pioneer amp all went well for 6 mnts now all of sudden bass power in minimal at best and when i turn the bass boost knob the sub move in and out as i turn the knob im stuck all parts were new 6mnts ago was working fine then all of sudden low power

 

[americanaudiophile]

Best guess is that when you turn the bass boost know the sub amp is sending DC into the woofers which would move the cones.
If you connect a VOM to the speaker terminals of the amp and measure a DC voltage over .5v then the amp is the problem.
The woofers may also be damaged by the DC output of the amp. You will need to check them on another amp or measure the impedance with the VOM.
https/www.wikihow.com/Measure-Speaker-Impedance