On my headunit, I have a subwoofer control. I can switch between 50hz, 80hz and 125hz.
Which would be the best frequency to use??

Headunit is a Pioneer DEH P-736
Amp is MTX Pro50X2
Woofer is 10 inch Kaption

 

50 would be the best for low bass.

 

When I played around with the controls, 80hz gives the most bass and 125hz is not bass at all but 50hz seems to gives the lowest volume in sound. Is it because the songs I listen to don't use 50hz and mostly 80 hz?

 

the louder bass on a system is usullay between 80-100, anything under 40 is inaudible u can only feel it, usually the bass gets louder from 50-100 or a little higher then slants off again. It all depends on what music you listen to

 

Wow... let's try some other stuff shall we?

1st, what kind of box is it? Sealed? Ported? Bandpass?

40Hz isn't inaudible. The human ear can hear 10Hz up to something like 18Khz.

I say go 120, and check the crossover on the amp ( could be why you have "no bass at all" )

 

80 is ussually a good cut off for most music types.