For those of you with subwoofer radio problems here is how to fix or adjust it. When we drove home our new coach from the dealer the sub stopped working. Come to find out the gain was set too high and the amp would automatically shut off. I had to turn the gain nearly all the way down so that the amp would not shut off. That meant that you couldn't get a good balance of sound.
Here are some problems with the stock sound system: Amp too small to properly drive the subwoofer (sub is rated 400 watts), cheap Chinese speakers, and head unit doesn't have adjustments for the sub. All you can do is adjust bass and treble for all speakers including the sub. In other words, if you crank up the bass, it feeds it through the tweeters and you can hear them pop. So, you have to lower the bass adjustment to zero or less on the head unit, and since you cannot adjust the gain on the amp...well you are stuck.
I will eventually replace all of it with better stuff, but I had an old amp laying around and decided to give it a shot. It actually ended up sounding 100% better. I'm still missing mid range sound, but overall pretty good. Now we can watch a movie and when a bomb is dropped, it doesn't sound like a firecracker. Being that the head unit doesn't have a separate option for the sub, I had to turn the bass to zero and treble all the way up for the tweeters, and now with a bigger amp I could crank the gain high enough to properly drive the sub. Not sure why FR mismatched the amp and woofer since the difference in price isn't that much. That little amp they installed goes for 30 bucks and I'm sure bulk would be much less. The 300 watt amp I installed goes for 50 bucks.
Here is the knob you have to turn down on the stock amp:
Here is the difference in size:
Here it is installed: