Takamine CTP-2 Cool Tube 2 Preamp The midrange frequency can be cut or boosted with the mid slider. The range of frequency covered by the rotary knob is 200hz to 8.5Khz. With this control, the player chooses the depth of effect the tube places on the signal generated by the proven Takamine "Palathetic" pickup. And harmonic density with fatter lows and rounder highs; or levels of rewarding richness for finger style players. An LED display reveals the note being played and directs the player with illuminated arrows that show sharp and flat.