jl audio components

I have a set of jl components and on the crossover box there is a switch that says tweeter level and its marked reference and -3db, whats the real difference between these positions will it just make it 3 db quieter?

Yes, it will make them 3dB quieter.

iser there really any point . I mean is 3 db really that noticible? thanks for the speedy reply.

it is kinda subtle, but sometimes you need it if you mount a tweeter closer than a midrange - or mount the tweeter in a place where there are lots of direct reflections