NoTrueSpaceman

I've recently gotten back into retro computing in the IBM XT clone genre. I obtained a set of Kaypro PC-compatible boards - a CPU card, a backplane, and a RAM card. I've been slowly working with them to build a 8088-based PC of the late…

I wrote earlier about a new eurorack synth module I'm working on. I left off having made a test bed that made some sort of sound but wasn't integrated with the synth. This weekend, I built out the test bed to a full prototype and really got to take it for a spin. Guess what? It's awesome.

Lets start by talking about what I finally decided to choose as an interface. This part is probably the most insightful design choice of the whole project. Earlier, I realized that I didn't need to worry about the envelope generators on the YM3812 and that I'd simply patch those in from traditional (and more versatile) eurorack modules. That leaves far less analog parameters:

• Operator 1 multiplier
• Operator 1 feedback
• Operator 1 amplitude
• Operator 1+2 pitch

The OPL2, aka the Yamaha YM3812, is a multi-voice FM synthesis sound chip. It was used in early PC sound cards such as the Adlib and a variety of other arcade machines and computers of the late 80s and early 90s. It operates completely digitally and produces sound via a specific DAC chip, the YM3014.

FM synthesis is an interesting way of producing sound and music but is particularly onerous to set up on a modular synth. These Yamaha chips (or clones thereof) are still easily and inexpensively available online. I decided a module showcasing the OPL2 would make a great addition to my modular.

If you're like me, you have a zillion unfinished projects sitting around. One of my goals in 2020 is to get some completed. But where do I start? In this post I describe an adaptation of a popular time management technique I've created to help complete my stack of projects.

I have a very modest modular synth which I have been building for the past year. I recently watched the complete "Modular In A Week" (MIAW) series on YouTube and was inspired to follow its example of making solid incremental contributions to my rig.

The MIAW series follows a conceit of each "day" of the week being devoted to constructing a single type of synth module: VCOs, VCFs, LFOs, etc. In my adaptation of the plan, I will work "across" the week to make a "voice" comprised of the VCOs, VCFs, and other modules typically found in a monophonic synth.