For someone who flies a plane with the TF-34's sister engine, the CF-34 (Bombardier CL-65), we use N2 (core speed) settings for lower rpm (mostly ground, crossbleed starts etc.) and N1 (fan speed) for higher rpm settings (when airborne). It's obviously a mix of both, but these engines are actually under electric fan speed control above a certain rpm (79% N2 I believe), which means they're "N1 controlled" at anything above that, while below this percentage they're under hydro-mechanical control or "N2 controlled" when you move the thrust levers.
(Sorry if I'm a bit rusty. That's what happens when you fly the somewhat bigger version of the same jet with FADEC controlled engines).
While I'm unfamiliar first hand with the specs of the TF-34, I'd say that's a safe assumption.