My Obsession with Feedback Continues

I have been working diligently at building my own synthesizer using an FPGA. I will be using a breadboard-mounted Cmod A7: Artix-7 FPGA Module.

My Obsession with Feedback Continues
Photo by Glitch Lab App / Unsplash

I recently spent some time with my digital audio workstation (DAW) putting together a heavily delayed feedback loop on the audio channels.

I split the audio and sent it to the input of the effect, then took the output of the effect and put it into the input of the audio channel. Sometimes, an effect would be chained to the output of another effect before returning to the loop.

I had to start it all with a delay so that I did not get distorted feedback.

After studying more about Digital Signal Processing, I learned that this is how an FIR filter works, too. It seems that nature likes feedback.

Building a Synthesizer on an FPGA

I have been working diligently at building my own synthesizer using an FPGA. I will be using a breadboard-mounted Cmod A7: Artix-7 FPGA Module.

To generate the audio waveforms, I will be using a Koolertron Waveform Function Generator. It can be hooked up to a computer for remote operation, so I'm going to see if there's an API or some other way to create custom Waveforms. That would be a cool way to integrate Algorithmic Composition techniques to control an external synthesizer.

Koolertron Arbitrary Waveform and Function Generator

I also bought a new Hantek DSO2C10 Oscilloscope to help me monitor the output of my filters and effects. It can also be hooked up to the computer and remotely operated.

Hantek DSO2C10 Oscilloscope

My plan is to send a waveform into the FPGA that is "programmed" with the filters and effects. I'll then route the output to a DAC (Digital to Analog Convertor). I need to study up on the datasheets of the various DACs out there to determine which one is suitable for my needs. I may not need it, I'm not sure.

I also bought a vintage BNC to XLR cable so that I could connect the signal generator directly to my Zoom 6 recorder (I use it as an audio interface for my computer). It would also work with a BNC to 3.5mm male audio cable.

Zoom H6 Audio Recorder and Computer Audio Interface

After I have generated the signal and processed it through my custom filters and effects on the FPGA, I will send the audio signal into the computer where I'll use the audio channels as an input and feed it through all of the effects I have at my disposal in my DAW, including my feedback effects chain.