This is Part III of a multi part series on building your own effects. See Part II and Part I Here.

I Finished the prototype of 'Bunny Cruncher', my cute little distortion unit. Thanks to 'D A F', Harry Bissell and Aaron Bader from the SDIY mailing list, I was able to get the output to a much more acceptable level. I changed the collector resistor to a much lower value, (10K) and added a biasing resistor. The Biasing resistor is super high in value, but it works. I also changed the caps to 10uF. Now it distorts just fine. A few more tweaks and revisions, and I'll have something hella cool.

Next up on my plate is to get a pure sine-wave sent to it, and start to really tweak with the diodes and see what kind of interesting effects I can make out of it.

I also did the schematic in eagle this time. MUCH BETTER. Eagle is much easier to use when laying out a schematic, but there is some VERY deep mojo going on there. If I were to try and make a PCB with the schematic as stands, it would fail. Badly. Mostly because there is a disconnect between the components that I have, and what is actually displayed. For instance, the 2222A transistor I have is in the typical black plastic crescent moon shape, but the one displayed in Eagle is one of the weird cylindrical metal units. Here is the schematic in Eagle Format

Ah well. Cross that bridge when I get there.

This is Part II of a multi part series on building your own effects. See Part I Here.

So, I cooked my own distortion. To the left you can see the schematic that I ended up with. This is modified from a schematic Here. The two bits on the left and the right are the input and output respectively. Please excuse the lameness of the schematic. Jonathan hooked me up with Dia, and while its relatively simple to use, I didn't really want to fart around with it that much, I just needed to get a quick and dirty schematic up. So it is quick, and dirty.

And It works! Its not perfect, but it works! It makes a really nice crunchy grindey distortion, but it is also somewhat 'clean' in its distortion. Its not at all like overdriving a Mackie. I do like the sound. The next step is to try and figure out why the output is so low. I tried playing around with the value of the 400K resistor, but it didn't seem to make much of a difference. After I have this thing in fully working order, I am going to play around with adding some more in the "feedback loop" between the 2222A and the 2 diodes. I am probably going to had a sweepable low pass and sweepable high pass filter.

Once I have all these basics down, I am going to look at making the thing pluggable. I want to eventually have it so you can change out the feedback generator (i.e. switch to an op-amp), Add things to the feedback loop, pre-distortion and post-distortion.

All this work has also given me an idea on what a good electronics prototyping breadboard needs. Right now I am using Shells "Vulcan Logic Trainer", which has all kinds of interesting bells and whistles, for... well... logic programming. Not so good for audio. Hell, when I was testing it, I was forced into holding 1/4 inch plugs up to the bare wire. Bah. Suckage.

This certainly isn't a new idea, but I've totally been bitten with the diy bug. My plan is a distortion unit that utilizes a 'pluggable' architecture. The idea is that you could plug in small modules at the various stages of the distortion so that you can change the sound. In any given distortion unit, you generally have 3 stages: Input, Feedback loop (where the distortion actually happens), and Output. The kind of modules that I am thinking about are filters (to color the sound) and specialized circuits on the feedback loop to change the shape. There is no reason why other circuits couldn't be added to this as well. Things like a ring modulator, resonant filter, or something.

Each plugin unit would have its own bypass switch and controls. Also, when a unit is not plugged in, it should just bypass the signal, rather then break the circuit. I'm not entirely sure what kind of plug I should be using for this part however. I do have the circuit block diagrammed, the next step is to block diagram the plugin elements, and then to do the physical layout. After that, I can think about the actual components of each piece.

As I keep going with this project, I'll post it.