Mrbook’s Stuff

Just wanted to share this pic I took at our last show. A Schizopolitans show is this times 4. We all have way too many buttons to push, cables to connect and knobs to turn. For all of us, juggling through all this stuff usually make the shows a little extra interesting

Many people have asked about the instructions and code for the SX-150 mod I did to add MIDI and Audio out, therefore I’m posting the plans for everyone to try. By using the Arduino as the brains of the operation, a lot of other options are available for the mod, really the sky is the limit. If you do any cool hacks to it, by all means, please let me know.

Parts List

• Gakken SX-150 Analog Synthesizer Kit
• Arduino (This one is the classic, but my favorite ones, are the ones from Modern Device)
• MCP4921 12-bit DAC
• 4N28 Optoisolator
• 1/4” Audio Jack
• DIN 5 Pin Chassis Socket (Female MIDI plug)
• Diode (N4148)
• Resistors(220 ohm, 100k ohm and 3.3k ohm)
• Wire, breadboard (or wherever you wanna do the circuit), soldering stuff and patience.

Connections from the synth

The contact spots shown on the picture refer to the connections on the schematic. Just make sure to get these ones right and that the soldering joints you make are pretty solid.

Casing

This part gives you a chance to be creative, so get your tools out and make something cool. For my mod, I used a cigar box, and made holes for all the cables that will get connected with the main circuit. I used epoxy to glue the gakken to the box and it is doing pretty well so far.

Just make sure that you will also be able to change the batteries when planning your holes.

Circuit Schematics

NOTE: It was brought to my attention that the connections P1 and P2 on the Gakken SX-150 are reversed on the schematic above.

Arduino Code

HakkenGakken.pde

Note that there is support on the code for a LED on digital pin 3 that flashes as notes are played. This has not been added on the schematics and it is optional.

If you improve the code, make some other cool mods or have questions, let me know!.

I’m now working on a standalone Arduino based MIDI sequencer on the cheap that can drive this little toy. Updates coming hopefully soon.

I finally got around to finishing the hack to my Gakken SX-150 mini synth. On the first part I added the ability to be controlled by Arduino through a virtual software midi port. On this iteration, I added a real midi in port and I also added a 1/4′ plug audio out, to make it more usable with standard audio equipment. For more picture you can take a look at the flickr set.

The MIDI part consisted in combining the Arduino MIDI IN circuit and the Voltage Control Circuit described on the first part of this hack.
And, this is how it sounds!

Do not, I repeat DO NOT use a 16V adapter on a Boss DD-20 Giga Delay, or this will happen to you. I’m not sure what kind of chip is the one that burned, but its original writing was BJSL. If you know the chip that is burned (IC12) please let me know! I’d like see if I can fix this.

It seems that during February, other than my super favorite FAWM, there are plenty of other interesting things going on, that have the same “goal oriented” objective. Well, for one, there is the RPM Challenge, where you also do music, but you have to actually turn in a CD at the end of the month.
But, I just discovered this other one, Thing-a-day, where you pretty much pick your poison, do something everyday and document it. This also sounds pretty interesting, specially because some people are able to exploit their creativity, without being framed by a format or activity.
Case in point, (pretty awesome btw), this guy made one instrument a day for the month of February.

Ranjit’s A Hand-made instrument a day

After seeing the original video online, I couldn’t resist putting music to it (and the mirror effect).

The song is called Cell Theory.

http://www.youtube.com/watch?v=g4RoqA7NreE

http://www.myspace.com/schizopolitans

It has been a couple of months since it has been released, but I never did the shameless plug in here so here it goes:
I have gathered the outcome of my FAWM 2008 participation and put it on a nice CD format and it is available for sale through CD baby. So… if you are feeling adventurous, why not buy it? is cheap!

Here are a couple of full tracks, for your enjoyment.

Mixed-up Logic [download]

Sunday Morning [download]

Also, for more music, my myspace page is http://myspace.com/nextdoorninja

The Gakken SX-150 is a really inexpensive analog synth (about $50, now available at the make store). This synth is included on a Japanese magazine (I wouldn’t expect less from them) so that makes it 2*2 times as cool.

Since its release, someone already has created a module to add midi support to it using the atmel attiny2313, but I’ve wanted to use an Arduino board to do it, to keep things easy to prototype and hack.

My implementation uses a single DAC IC chip, the MCP4921, which sells for about 2 bucks from Mouser. The current version uses the Arduino, only to read one byte, as a midi note, from the serial connection and sends that to the SX-150. I could have created the full midi circuit to make it a standalone solution, but that increases the cost and complexity of the physical connections. I’ll probably do that on a later revision.

So, in order to receive midi data, I wrote a small Processing sketch that receives midi, and sends the note information through the serial port to the Arduino.

The Arduino connection diagram looks like this:

And the final connections, like this:

And.. the whole thing sounds like this:

On the video, I’m using Ableton Live to send midi data to the processing sketch using a Network Midi connection on the Mac. On windows, you should be able to use Midi Yolke to accomplish the same thing. Then, I make sure that the processing sketch receives midi on that same virtual midi connection and sends the data through serial to the arduino. So, depending on your system configuration, you might have to tweak the Processing sketch a little bit to make sure it is reading and writing to the right midi and serial ports.

The flow of data from the sequencer to the synth looks like this:
Ableton Live => Virtual Midi Connection => Processing Sketch => Serial Port =≶ Arduino => DAC => SX-150

And finally, the source code:

• Arduino Code
• Processing Code

Now, hook it up and make some noise!