I have tried a lot of things to fix this, and can't seem to pin the problem. Got a JL w1v2 hooked up to a Phoenix 1000W max. Got the sub hooked up bridged, 300W RMS on 1 ch. Problem is that the sub stops hitting once you turn the stereo volume past lets say 40%. The light also dims on the amp when the sub doesn't hit. Lack of power? It constantly gets over 13.3V when the engine is running. The ground cord is also short and bolts to th spare tire bolt. Th sub hits hard until the volume goes up. Thanks for the help.

 

I would say to try a different grounding point and make sure that you scrape off any paint under the connection.

ONe more thing. What gauge wire are you using for both the power and the ground?

 

Specs of wire:

# 17 ft of Ruby red 8 gauge power wire
# 3 ft of Onyx 4 gauge ground wire

 

my guess is the amp is not strong enough if the ground wire isnt the case, you could also try going with a shorter ground wire

 

power and ground wires should be the same guage, and your ground also should be a foot or less, 3ft is way too long.

Besides that, did you set your gain properly? Your amp might be clipping due to improperly set gain.