Wednesday, March 19, 2014

x0xi0 #330-133.5 : Full Build. Next Steps

The x0xi0 mid-build in 2011.
As you can see, this x0x build hit a wall. I followed through the original documentation and built the whole kit in place of doing it in parts. I then had to shelve this project since there were some gaps and errors in those PDFs. I've done numerous other projects since.

A recent x0x repair for someone else inspired me to finally put this project to rest. This has turned out to be advantageous since Brian's documentation is now into its fourth revision and appears to be quite complete. I've been able to do a sweep of updates with little risk and the results have paid off.

2014. It looks sad now but all will be well soon.
So, now that I've reviewed where I left off, here's where it stands. In the interest of extreme experimentation I've socketed most of the transistors and a few key components:

  • R47: This extends the low range on the x0xi0
  • R61: this controls the ENV MOD setting when Brian's pot is set to 0. 10K is the default in the document.
  • R97: as per my original build, this adds a 'natural' boost to the resonance. Some people add a pot for this. I don't see the point. 10K is what's in the document. My last build provided boost at 9.2K. My final decision for this build is pending. What I want is the same behaviour as the the last build. 90% turn in the pot gives my a proper 303 calibration. The extra 10% is the boost and nearly reaches self-oscillation. More than enough for me!
  • C21: This add more bass boost and in this case has an effect on VCF Out as well.
The LEDs were also never placed so this task is under way now. here's a dorky photoshop file I've kept on hand to experiment with color combinations:

I'm using the same set of LEDs as the last build but different values appear to be useful here. These will be more intense than the first build but I have time to try out a few combinations.

Blue: 5.6K Ohm
Purple: 100 Ohm
White: 2.2K Ohm

3mm - pending delivery of custom LEDs:
Blue: ?
Purple: ?

There's also loads of wiring to finish up. My pre-assembly calibration succeeded though. VCO, VCF, and ENV all check out.

It's getting there. I want this finished so I can finally have some fun with it.