A Single-board Modular Logic Noise Synth Monster
Because of the way the Klangorium kit is built, it's a little bit difficult to get the overdriven triangle wave sound out of it, but because I love that sound so much, I'm going to show you how.
The regular triangle wave is easy-peasy. First off, just tap into the input and connect it to the high-gain mixer out. Done. On the breadboard, we needed an output-buffer stage, but here the output amplifier / active mixer serves the same purpose.
The overdrive effect relied on running our sound through a unity-gain buffer stage and then through another amplifier stage with enough gain to start distorting. The good news is that the Klangorium has two 4069UB inverter stages free. The bad news is that we're going to need some extra parts.
In particular, we'll need two 100k resistors for the first stage buffer, and a 100k pot and another 100k resistor for the overdrive section.
You can connect these into the circuit however you like, but I find it easiest to take two female-female cables and insert the resistor in the middle. You've effectively got a double-length cable with 100k ohm's resistance. Make three of these, and then do the same thing with the potentiometer.
Now, starting with the input terminal of an oscillator (where the triangle waves come out) connect it to the input of one of the buffers with the 100k ohm cable. Connect the output of that buffer to it's input with another 100k ohm cable.
Now using the potentiometer cable, connect the output of that first buffer to the input of a second. Using the last 100k ohm cable, connect the second buffer's input and output together. Finally, the output of that buffer should go to a low-gain mixer input.
You should be able to control the pitch of the triangle wave at the oscillator and the overdrive with your external potentiometer. Woot.
And do note that a little overdrive can be tastefully applied anywhere. For instance, it's great with the drum voice.
Say you've got the board and parts in front of you. Congrats! Now put it together.
It's not hard, but it's got 550 solder joints. The good news is that none of them are particularly critical or difficult. If you're a beginner with the soldering iron, you'll be experienced by the time you're done. (Or you'll be driven stark-raving mad.) Even if you're a seasoned flux-wielding veteran, you'll need some patience.
I've built up a few of these now, and here's my advice.
First, put all the header pins in their respective holes.
Now get a piece of cardboard and put it on top of the pins before you (gently) flip it over. This way, you stand a chance of getting the pins aligned straight with the board upside-down.
Now solder in one pin from each header, to make it easy to adjust any that are screwy.
Only once you're content that they're all in straight, solder the headers in for real. It's a lot of soldering. Take a break when you're done.
If you've followed along with the Logic Noise series, you've noticed that I designed the sessions to build on the previous ones. Because the board is essentially modular, you can now do the same assembling it.
That is, build a section, explore it, learn it, internalize it, and then move on to the next section. Think of this as a pleasant stroll through the pastures of silicon synthesizer possibilities, rather than as a project you'd like to get done fast. It'll keep you sane.