Giulio Zausa Turns a Roland MKS-70 Analog Synth Into a Convenient USB MIDI "Zombie"

Software engineer Giulio Zausa has turned an awkward front panel-programmed vintage analog synthesizer into something accessible over a USB connection — using just $2 of components.

"[This] is a Roland MKS-70," Zausa explains of his recent acquisition, "an analog poly synth from 1986. It has two digital oscillators, analog filters, and 12 voices. It was a very professional and expensive machine when it came out, and it ended up being used in a lot of very famous records. Think about the soundtrack of Twin Peaks, or the riff of The Final Countdown by Europe. How cool is that?"

By modern standards, though, the MKS-70 has a problem: if you want to edit the sound in real-time, you have to navigate a labyrinthine menu system using front-panel buttons then dial-in individual parameters using a rotary encoder. It's usable, but it's far from convenient — and, spoiled by modern devices, Zausa missed that convenience.

To begin, Zausa disassembled the synth and investigated its inner workings — aided along the way with schematics available in the device's service manual. Keeping the voice boards intact, Zausa sought to bypass the digital control board and simulate it in software instead. A low-cost logic analyzer allowed him to sniff the signals to the voice boards and determine exactly how communications from the control board take place.

The addition of a $2 USB-UART bridge board to the synth was the only thing required on the hardware front. Once in place, Zausa could use a laptop to send his own commands to the voice boards without touching the front panel at once — except it didn't work, a disheartening start which thankfully turned out to be a simple baud rate mismatch.

"The program that I built creates a virtual MIDI port which appears in software like Logic as external MIDI device, so you can create a new track in Logic and directly route it to the MKS-70," Zausa explains. "The program that I wrote listens to the new MIDI events that are coming from Logic or from your DAW [Digital Audio Workstation], and it converts those commands into commands that the voice board can understand, and then it sends them."

More details on the project are available in the above video, while the source code — which Zausa dubs the "Zombie Utility" and which is compatible with voice boards from the Roland JX-10 and JX-8P in addition to the MKS-70 — is available on GitHub under an unspecified license.