Passive SUB question

[SterlingFan]

One thing I don't understand. The passive SUB has a control for bass and treble.
Since it's passive, how do they work? Most passive basses only have one tone control.

 

[Bassplyr]

The bass and treble can only be cut, not boosted (as in an active bass). So you can either have them at 0 or less. I know of alot of other passive basses that have a bass and treble, then there are some with 2 volumes. But either way, you'll be making more adjustments on your amp.

 

[SterlingFan]

Thank you.