My Gakken Diary, Part Three: First Music

I finally got it together to make a piece with the Gakken SX-150. My basic idea was to treat the Gakken the same way I treat my Arp Odyssey: run it through a Line 6 DL-4 in looper mode, with a long repeat time, to emulate tape delay with feedback. Much of the work I do with the Odyssey involves modulating consonant intervals in the filter with a combination of envelopes, sample and hold and the LFO. I like making automatic music with the Odyssey, using a slow LFO to trigger events, and using different kinds of feedback in patches to get the synthesizer to more or less play itself. Needless to say, this isn't really possible with the Gakken, and it requires a lot more manual intervention than the techniques I've worked out with the Odyssey.

This first piece was made almost entirely by tweaking just two parameters; the filter cutoff and the amount of LFO modulation applied to the oscillator. Because it's very easy to slip with the small stylus on the carbon strip, the third parameter is a kind of manual oscillator drift. You can get some very nice beating effects by sending tiny tuning changes into the delay, just by slipping a bit on the carbon strip with the stylus.

Here's the piece:



And for comparison, here's a piece from 2004 using the Odyssey:

My Gakken Diary, Part Two: Mechanics

Last night, after putting this thing together, and making a few preliminary experiments, I began to wonder if I had broken it somehow, because a few things did not make sense, at least not based on my assumptions of how a synth should work.

So I spent some time squinting at the schematics in the magazine, looking at the various videos online, and reading posts on Analog Haven via Nabble, and I came to the conclusion that the design of the Gakken SX-150 has some unique points.

Here's how I put it all together, based on my years of doing subtractive synthesis on and Arp Odyssey:

• The LFO Rate only affects the pitch of the VCO. You can't also assign it to the VCF. So it goes.
• This is the weird one. The VCF appears on some level to be a combo VCF and VCA.
• The above assumption is borne out by the fact that, at first, when I cranked the Cutoff on the VCF all the way to the right (or anywhere past about 2 o'clock), I couldn't get the Attack and Decay (AD) in the EG to have any effect when using the stylus. My original assumption about this synth was that the EG would be invoked when you touched the stylus to the carbon strip. But with cutoff anywhere above 2 o'clock, touch the stylus and its note on/note off. No shaping from the EG. It wasn't until I turned the Cutoff down to about halfway (below 1 o'clock) that this would happen. So that's where I get my theory that the VCF is sort of a combo VCF and VCA.
• Pitch Env takes the settings from AD on the EG and applies them to the VCO. If you combine Pitch Env with the LFO, you can get some interesting Frequency Modulation effects on the VCO.

I'm posting this in the hopes that someone else comes along, reads this, and either agrees with me or points out where my thinking is wrong.

My Gakken Diary, Part One

Like many synth nuts, I've been reading since late summer on the Matrixsynth blog about the Gakken SX-150, the tiny analog synthesizer, in kit form, that comes with the Synthesizer Chronicle issue of the Japanese science magazine Otona-No-Kagaku. Two weeks ago, I finally decided to get one. I found one through a bookseller in Japan with an E-Bay store. I received it last week.

I'm not sure any outfit here in the U.S. could produce a magazine like this. The Synthesizer Chronicle itself is tucked away behind an extra cover, whose background art includes the divine Arp 2500, under which is a cardboard box containing the actual Gakken SX-150 kit. The magazine covers 50 years of the history of the synthesizer, with lots of photos, plus memorabilia items such as Yellow Magic Orchestra stage diagrams and master tape track sheets. Countries of origin of synths covered include the U.S., the U.K. and Japan.

My day job is at a college with a substantial population of international students; my first impulse was to find a Japanese speaker to help translate the instructions for assembling the little synth. But the pictures in the instructions are clear enough, and this Flickr set fills in the rest of the details. For those of you who just got one, and are about to embark on this project, I've got two additional pieces of advice:

1. Run the blue cable (the one that attaches to the carbon strip) behind the post that the circuit board screw goes into. Otherwise, the cable may float around to the right of the power switch.

2. When you're finally dropping the circuit board into the case, make sure to flip the synth over to actually see that everything is popping through the right holes before you screw it all together. The instructions skip this step, and I discovered that the power LED wasn't in its proper position.

For those of you who haven't ordered one yet, or whose synth hasn't arrived yet, I have this word of advice: This is a kit attached to a magazine that (if you're lucky) you paid about 60 bucks for before shipping. It's not exactly made to the same specs as a Moog synthesizer. The knobs and pots in particular are a little funky. I always marvel at how people in Flickr sets get objects to look so beautiful. The magazine does a great job of photographing it too.

Well, by the time I had mine all put together and was running it through its paces, I felt a feeling I hadn't felt since childhood; wanting something really badly for Christmas, opening it up, putting it together, and then realizing that it's a really just a little piece of plastic trinket. Well, I put it down, made dinner, and came back to it, and now I'm back to where I was originally. It's pretty cool. I'm not going to establish an entire artistic oeuvre around it, because it's not going to last more than five years. But it's going to occupy a spot in my arsenal right next to my Cracklebox--a portable device for wandering around the hall, making unpredictably spontaneous, hard-to-control sounds above the drone.