I was hoping to be writing that I had finished the design and had started the final layout, but I’ve got one more thing to get sorted. I’ve found that digital scaling in the 8 bit world has serious audio problems and I’m implementing some more analog circuitry to resolve it. As usual, I’m hacking my way through a well beaten path but I’ve never done it before so it takes some thought and experimentation. My usual limitation is to try to find the cheapest, lowest part count, and most consistent solution. I’ll post about the final solution, hopefully soon.
Otherwise, I’ve made huge progress. I’ve ditched the R2R DAC because it has linearity problems. I’ve wrapped up the filter after a bunch of experimentation and a couple misleading wrong turns. The final filter is going to sound pretty cool. I’m adding a bunch more waveshapes for synthesis and for the LFO which works very well. MIDI in and out are fully functional and implemented. I also got patch storage and recall working. So, it’s almost all there. One more thing to figure out and then it’ll be the final layout. In the end, I’ll be posting this project initially on Kickstarter as a way to generate the money to get started. I’ve got another investor, but I’m hoping to be able to do it alone. Anyways, send me an email or post a comment if you want to know more.