In most active basses you can both cut and boost frequencies. Think of the center position (you probably have a center detent) of your treble knob being the equivalent of the fully open (10) position of the tone knob on a passive bass. When you turn your treble knob past 5 you are boosting the treble frequencies higher than “normal” and you’re also increasing the amount of noise produced by the preamp. I think if you stay between 0 and 5 on your treble knob for normal playing and just go above 5 when you want to “cut through the mix” for certain parts of songs the sound guy will probably get off your back. 
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