GmanModz

With all the hype around polysynths this week, I thought it would be a good time to share that I’ve started my own analog polysynth project a few weeks ago. This is something I’ve been wanting to do for a while but have put it off because I know it will take a lot of time and be expensive to finish. I think I’m up to the challenge!

I’ve planned out most of the synthesis architecture. 2 VCOs, a filter, and plenty of VCAs for control. The envelope generators, LFOs, and other modulation will be done in software. My first goal is to work towards an SPI programmable monophonic analog synth voice. Then to make it polyphonic, I’d tie a few of them together with a master SPI unit that gathers preset data from the control panel, keyboard, and other inputs.

An early model showing all the routing options. I will be adding onto it and revising it when I create the schematic for the voice card.

What I think makes this architecture interesting is that VCO1 will be a triangle core, and VCO2 a sawtooth core. This allows me to implement two different oscillator syncs that work differently for each core. When synced, the sawtooth core is reset to 0v, but the triangle core output is reversed. It is a subtle effect, but I think it will be cool and there is a lot of variety I can do with this approach while keeping the part count down.

I’ve borrowed the waveshaping circuit from the Micromoog, I think it is very clever! It allows a continuously variable waveshape from saw to square to narrow pulse using just a transistor and 3 op-amps!

And here’s the triangle wave going through the same wave shaping circuit. The outputs look good so far.

After breadboarding a basic LM13700 VCA circuit, here is a sawtooth wave whose amplitude is modulated by a triangle wave, it works!

A lot of work to be done. That’s all for now.

The G-Wii is a Wii portable I’ve been doing on commission for quite some time. Even though I’ve been putting a lot of effort into custom PCBs lately, this one is assembled without any custom parts! It’s a relatively easy build so I have decided to release all the CAD files including complete SolidWorks assembly and STLs for 3D printing. A simple Wii portable foundation for beginners to get started is something that’s been needed for a long time so I hope to see more Wii portables being built. You can grab the files here

A little more about the process:

After modeling the case on the computer, I 3D printed it in PLA, applied bondo, and sanded it until it was as smooth as possible. I used several coats of primer to achieve this.

I had to relocate the MX chip in this build so that way I could use Nintendont compatible with the OEM GC memory card since the customer requested that feature. I am not generally a fan of using hot glue, however I used it just this once for temporarily holding down the USB port mount until it could be screwed in during the final assembly.

It’s all hand wired together which shows is still relevant in this age of custom PCBs. I used 4x 18650s to give about a 4 hour battery life. The VGA screen looks great with the VGA patches

To avoid more glue, I designed 3D printable mounts for all the parts I could and secured them using M2 screws.

Thanks for reading. I’ve got some big projects coming up and I hope to keep this up.

Hey everyone. Here is my new website where I plan on sharing project updates and other things modding related. There isn’t much to see yet but I hope to put more together in the next few weeks. Thanks for joining!