Audiophiles go to great lengths to get the absolute best sound possible out of their audio equipment. Sometimes they even buy super expensive hardware of dubious value because they are convinced they can hear the difference — even if the product’s claims defy the laws of physics. But you know an audiophile is truly all in when they go so far as to build their own hardware. That way, every piece of the system can be customized and tuned to suit the owner’s unique tastes.
That could be a very costly undertaking, but Nerd Musician has demonstrated that it is possible to build your own equipment on a budget. You will have to make some compromises, but at least you will know exactly what went into it and how to tune it perfectly to your liking. Specifically, Nerd Musician built a custom DJ controller — and you can too with about $30 in parts and a free weekend.
Designing the circuit with MIDI Controller Builder (📷: Nerd Musician)
The project is designed around an Arduino Pro Micro that packs enough power to function as a native USB MIDI device. Rather than relying on expensive commercial hardware, the controller uses a collection of readily available components, including two rotary encoders fitted with large 60mm 3D-printed jog wheels, five potentiometers for filters and volume control, and five arcade-style buttons for programmable functions.
To keep things simple, the design uses every available pin on the microcontroller without resorting to multiplexers or expansion boards. That approach keeps costs low while still providing enough inputs for dual-deck DJ operation. The rotary encoders handle jog-wheel duties, while the potentiometers serve as deck volume faders, audio filters, and a crossfader. The arcade buttons take care of controls such as play, cue, and shift functions.
To simplify construction, Nerd Musician used exposed solid copper bus wires as common power and ground rails. This method dramatically reduces wiring complexity by allowing multiple components to share the same connections. Individual signal wires then run from each control back to the microcontroller.
The assembled device (📷: Nerd Musician)
Using the web-based MIDI Controller Builder application, the layout was arranged digitally before being exported for 3D printing. The resulting case consists of a top panel and bottom shell with integrated mounting features for the Arduino. Custom jog wheel caps and multicolor printed parts give the finished controller a polished appearance despite its modest budget.
After assembly, the controller is programmed using the Arduino IDE. Once configured, the device appears to a computer as a class-compliant USB MIDI controller capable of sending standard MIDI messages. Specialized output modes allow the jog wheels to work correctly with professional DJ software such as Traktor, which expects relative directional encoder data instead of traditional absolute values.
In the end, Nerd Musician had a DJ controller that delivered many of the functions found on commercial hardware while remaining affordable, customizable, and fully open to modification by its builder. Be sure to watch the video below for more details.