The crossover knob goes from 30Hz to 120Hz.
Does anyone know if the crossover scale on T series Subwoofer is linear i.e. 75Hz at 12 o'clock?
(120-30=90 so half way there is 45 plus starting point at 30Hz gives 75Hz at 12 o'clock)
The scale on the crossover control is not linear, so I'm pretty sure 12 o'clock is not -3dB point at 75Hz. It's closer to 50Hz.
In our experience setting up Tzeros, 12 o'clock is the best place to start with both the crossover and level controls. Most room set are within +/- 3 clicks from that 12 o'clock position. By click, I mean the detents you can feel with exercising the controls.
I'm sorry there are no marks between the min and max of the crossover control of the Tzero. I'm sure this was a style decision.