Ultramaster KR-106

A Quarter Century in the Making

Ultramaster Group was born in the year 2000, in a loft in Brooklyn, NY. Their bold mission: professional-grade audio software for the Linux ecosystem. They were young, idealistic, and perhaps a little bit ahead of their time.

Life eventually pulled the founders into different orbits. Karl went on to found the art and design powerhouse Kayrock Screenprinting, while Dave joined the engineering teams at Google. But the music never truly stopped.

Twenty-five years ago, they were targeting the Pentium Pro, working without the luxury of oscilloscopes, service manuals, or community hubs like ModWiggler and Reddit. Today, after decades spent designing Kayrock Powertools and scaling global infrastructure, they have returned to the Juno source code.   

A lot has changed since the late 90s. Hardware is exponentially faster, and DSP methodology has evolved. The team has spent time heavily recalibrating and refining the engine for the modern era. While the interface remains intentionally familiar, the internal architecture has been overhauled for better performance and precision.   

Ultramaster Group is rereleasing KR-106 as an open-source project under the GPL to give back to the community that inspired them from the start. Their goal is to make the software as accurate as humanly possible, and they invite users to help them get there.

Support the Project

Ultramaster KR-106 is, and always will be, 100% free and open source. We don't take donations, but if you'd like to support the hands behind the code: for Karl, visit Kayrock Screenprinting or check out Kayrock Powertools. For Dave, just go use Google Maps or something.

Have a Juno-106?

Help us calibrate the KR-106 by recording a few factory presets on your hardware. We provide MIDI files that program your synth via SysEx and play test notes. Just hit play, record the output, and send it our way. The more units we hear from, the better we can model the real thing.

Features

• 60 / 106 Mode
• 6/8/10 Voice Poly
• Band Limited DCO
• IR3109 VCF
• MN3009 BBD Chorus
• DAW Synced ARP and LFO
• 128 Factory Presets
• Oscilloscope
• Component Variance
• QWERTY Keyboard
• MIDI Learn + SysEx