Big Knob expression port knob controller. This simple device is a heavy-duty CNC machined black anodized knob for use with your expression port on any midi/usb keyboard controller. Simply plug into your expression port and immediately have a 0-128 mappable control knob. Currently there are 10 spring loaded detente positions and a hard stop for quantized physical snapping, however by removing the 1″ chromed steel ball bearing and spring, you can create a smooth position knob controller. The detente disc is made from self-lubricating delrin which both supports the potentiometer and creates a smooth snap in with the chrome spring loaded ball bearing. The stainless steel frame is adjustable and clamps onto either your keyboard or table.