Mad_Cyril …not really like a crossfader, no.
Imagine one knob had the functionality of a 3 or 4-band EQ. The first third of a turn removes the bass end of the frequencies, the second bit the mids, the last bit sweeps-up the highs. I guess the main difference between it and an EQ is that it is just subtractive, ie. you can’t use it to boost frequencies, just take them away… then again, I don’t know many DJ’s that push frequencies on a mixer using the EQ in that way, I certainly don’t.