MIDI DJ Controllers are being adopted by shortwave listeners and hams to provide extra tuning knobs and switches. Looks like fun!
Typically, a software defined radio has been a “black box” radio controlled by a computer. All controls have been virtual – menus, buttons and sliders on the screen, and a mouse. For example, you change frequency by clicking on a spectrum scope, and perhaps using your mouse wheel to adjust the frequency up or down. I can live with most of the “virtual controls”. But I really do miss a real big tuning knob.
Enter the MIDI DJ Controller. These are gizmos used by musicians and deejays to control instruments and playback gear. Typically, these controllers cost $150 and up, although they are readily available on the used market.
You will find these MIDI boxes have three types of controls. First, they have push buttons that trigger actions, either when pressed or released. Second, they have range controls – either sliders or knobs – that give you an output between 0 to 126. Third, and most important, are the continuous rotation optical encoders. The MIDI DJ Controller shown above has two large spinners that can serve as tuning controls for an SDR. All you need is a way to interface these controls with your radio software.
MIDI DJ Controllers – How they Work
MIDI (Musical Instrument Digital Interface) is a technical standard that describes a protocol, digital interface and connectors and allows a wide variety of electronic musical instruments, computers and other related devices to connect and communicate with one another. MIDI has been around since the early 1980’s and has been used extensively for digital music and more recently, device control.
The standard includes methods of connecting devices together, as well as messages that represent musical notes and effects, as well as controls. MIDI is essentially an 8-bit serial bus running at 31,250 baud. In the past, sound and gaming support cards contained a five pin MIDI connector. These days, you find most MIDI devices connecting over (and getting power from) USB. Most Windows, Apple and Android devices have native MIDI support.
I just picked up a Behringer CMD Micro DJ Controller cheap on Kijiji. After plugging it in, I downloaded MIDI-OX software to monitor the signals sent by the controller. Most signals are two bytes long. Soon, I will hook up this box of physical knobs and buttons to help control my SDR gear. The big tuning knob will return in style!