I developed a presentation as part of my Sprockit workshop. I think it’s a pretty clear presentation of wavetable synthesis and that it clearly shows how aliasing happens and how to avoid it. I’ve often found that it is difficult to find this type of clear and simple explanation of fundamental synthesis concepts that is particularly useful for the DIY Synth community. So, click through for some learning…
Hello everyone. Big shout out to all my backers out there. Thank you for all your support over the past couple months. Your messages of support have been instrumental in keeping me focused on the prize. I started this project with the goal in mind of forcing myself to find an ending to this project after about a year and a half of work. And I think I’ve done it.
In the new video, you’ll notice all the work that I’ve put into polishing the design over the past two months. Mostly, I’ve been pounding the hardware. I completely overhauled the final output stage a couple times and spent some good time tweaking the DAC reconstruction filter as well as the main analog filter. The end result of this work has been to massively reduce harmonic distortion and to drop the noise floor way down. Along the way, I found a number of bugs in the code and made huge improvements in the wavetable playback that made aliasing a problem of the past.
Stay tuned after the project ends for details on order fulfillment and my next steps.
I’ve spent a lot of time in the development of the Rockit 8 Bit Synth dealing with aliasing. I made a MATLAB simulation to get to the heart of the issue visually. The script simulates the wavetable synthesis process by generating a sawtooth wavetable and playing back that wavetable to generate a 50% duty cycle square wave output. This output is plotted along with the Fast Fourier Transform (the frequency) of the signal By adjusting some parameters, the amount of aliasing in the signal can be increased or decreased, providing a visual tool for understanding the factors that contribute to aliasing in wavetable synthesis. Click through for a thorough explanation.
In a previous post, I discussed how in setting up my oscillators, how I made a proper demonstration of aliasing. I have yet to find a clear description of the problem as it relates to digital synthesis. There are many sites which define aliasing in engineering terms but don’t make it as easy a thing to understand as it can be. Follow along as I give it a shot.
China, naturally. Given that we build almost everything in the world that needs building in China, it’s a pretty natural place for an electrical engineer to end up. I spent two weeks there and another week after I got back recovering from some intestinal parasite. I’m as inclined to blame the airline as I am the delicious food I had in China for the bug that tried to chew it’s way out of my gut.