How Differential Audio Inc. Started

Five years ago, I set out to start a hobby project for myself, where I could create something interesting from the ground up.  As an electrical engineer by trade, I wanted to build some kind of electronic device from scratch.  I was looking for a creative outlet, where I had free license to build something without constraints and specifications, led by whatever creative feature I wanted to work on next.  I had experience in hardware based signal processing, and guided by my love for electronic music, was led to the amazing world of music synthesizers.

 The original hardware platform for this project went through many conceptual iterations - from utilizing a Raspberry PI, to a dedicated DSP chip, and eventually settled on an FPGA (a programmable computer chip).  I had selected additive synthesis for the architecture of the sound engine for one simple reason: it was rare.  After learning more about the computational requirements of additive synthesis, the FPGA programmable computer chip was selected over software implementations on a PI or DSP because it was much more powerful.

I got my hands on a low cost FPGA development board (Digilent Arty, below) and started work on the proof of concept.  My background is in computer chip design, which allowed me to get the concept off of the ground reasonably quickly.  It was fun to build a music synthesis engine from scratch with no constraints and it was a great escape from the day to day.

 fpga development board

Six months later, I was really excited about the sounds coming out of the (still primitive) additive synthesis engine on the development board.  This board served its purpose, but was limited in both the FPGA capability and I/O it could provide.  I was having fun on the project and wanted to take it to the next level, so I decided to take a leap of faith and develop a custom board.

Developing a PCB from scratch was a huge undertaking as much of it was new to me.  It was extremely satisfying to create a custom board with whatever I/O I wanted.  After the better part of a year developing the board, the PCB went to fabrication and assembly, and the 'Parker Additive Synthesizer' was born (see the logo near the bottom right of the board below).

additive synthesizer prototype

The Parker Additive Synthesizer sat on my desk for the next three years and became the development platform for the project, allowing me to write FPGA and software code, and interface to the I/O which included encoders, MIDI, ADCs and DACs, SD card, and display interfaces.

In the summer of 2022, my employer was generous enough to grant me a three month leave of absence from work, which allowed me to put my full time effort into the project.  As the capability of the synthesis engine and software control stack grew, I felt that I was really on to something of value and this project was unique in the synthesizer market.

I resigned from my employer in the fall of 2022 to pursue this full time, allowing me to productize this hobby project as the FS-256, and incorporate Differential Audio Inc.

What's Next?

The next iteration of the custom PCB as well as a custom enclosure have been designed and are being sent out for prototype manufacturing.  Following initial engineering work on these designs, a Beta program will be run with incremental improvements being made to the sound engine and user interface. Following certification, an initial production batch will be run and the product will be made available for sale. 

The following image shows an improved render of the final product, but is not fully representative of the final design.

FS-256 render


Thanks for taking the time to read this.  If you have any questions or comments please contact me.



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