2. Operating principles
The term controller naturally derives from the verb control, and thus refers to determining the operation of a device. As controllers are ubiquitous in a wide variety of applications, e.g. "computer technology" or "finance", let's first of all outline our field of reference. For our purposes, "controllers" are electronic units as part of a compter-oriented studio environment, which can regulate - control - various processes. Such a unit may be a piece of either software or hardware. A sequencer such as Logic, which controls a different program on a computer, for example "Reason" (master-to-slave operation), is one type of software controller. So as not to let our definition grow too unwieldy, we shall resrict ourselves to hardware controllers for the purposes of this guide.
The Korg Kaoss Pad Mini (Touchpad Controller)
Operating principles
A hardware controller consists of one or several controls which can come as rotary knobs, buttons, joysticks, faders, beam sensors etc, which track the movements and actions caused by the user and convert them into appropriate control signals. In principle, a computer keyboard does exactly the same thing, but it is unsuitable for delicate tasks - unless you want to enter pitch blend data manually....?
The signals thus generated are transmitted to the device to be controlled through an interface (MIDI, USB, mLAN, etc). The controller and the target device must therefore "speak the same language" to be able to understand each other. The target devices may be softsynths, VST effects, etc., but also hardware such as synthesizers or SysEx-compatrible effect devices. We'll address the topic of MIDI SysEx later on. Depending on the controller, one or several devices can be remotely controlled simultaneously, i.e. a single controller can instruct many devices either individually or collectively and adapt to the relevant target device as long as the controller has been appropriately programmed. Depending on the quality of the "intelligence" contained inside, the controller recognises the connected device or devices independently by running a MIDI scan and assigns appropriate functions to its controls and buttons.
