Review –  Gakken analog synth kit


MAKE Japan editor Hideo Tamura was kind enough to send us one of the new Gakken SX-150 Analog Synthesizer kits. Needless to say I was very pleased to receive it. The kit comes as part of the latest issue of Otona no Kagaku (Science for Adults) magazine/book(aka ‘mook’). Though unable to actually read the issue, I fully enjoyed the included pictorials on synth history and hack/mod ideas for the SX-150 – a ton of good stuff in there.


Putting it together
Assembly of the kit requires little work – the circuit board comes fully assembled, just mount it to the panel and connect the stylus control strip. Power is provided by 4 AA batteries and a small speaker is included in the design. I highly suggest connecting the output to external amplification (this little guy really does sound quite good!). The “external source” jack accepts an amplified signal and converts its frequency into pitch control. Controls for LFO, pitch envelope, frequency cutoff, and attack/decay are included. Each potentiometer gives a wide range of response, so you have a relatively large amount of control over the sound.

Mod me
The simple design seems to suggest that the SX-150 wants/needsto be modded, hacked, and/or customized. Using the stylus/pitch-strip control only gives you a taste of the good sounds you can get from the kit. I decided to replace the strip with some momentary pushbuttons and a small trimpot for adjustment. You can see/hear the results below –

The SX-150 kit is very easy to use and some modding ideas are bound to come to mind should you get your hands on one. At the very least, you can choose from a number of included decorative decals – and at the more advanced end, schematic and code for using MIDI input has already been posted. I’m sure more sweet DIY add-ons are in the works – very awesome.

Assembling the SX-150 on Flickr

Otona no Kagaku SX-150 issue

HOW TO – control an SX-150 via MIDI

more Gakken kits in the Maker Shed

24 thoughts on “Review – Gakken analog synth kit

  1. @shivam – Regretfully, I didn’t document the mod process – so I suppose no guide as of yet. Are you looking to add buttons in the same way or just a general orientation on the connections/wiring?

  2. I’m just looking for a general orientation on how to do that. I’ve just now started discovering a love for DIY electronics, and i want to do cool things with this kit =)

  3. I would love to have the details of how you did this. Seems really simple, but instructions or documentation would be needed for beginners like myself. Nice hack!

  4. I actually shot some video for a how to this week, likely be posted next.

    For those who can’t stand to wait – here’s a boiled down description.

    – replace the control strip with a chain of 7 4.7K resistors. connect one side of the chain to the white wire. connect the other side to the outside leg of a 100K potentiometer, then connect the 2 remaining legs of the pot to the blue wire.
    – connect one leg of a switch at the junction of 2 resistors
    – connect the other leg of that switch to the stylus’ wire (aka ground)
    – repeat @ every other junction where 2 resistors meet

    I gleaned the basic idea from MFOS –

    that’s the gist of it, i’ll post more detail soons!

  5. I think it’s lame that the external input does not work. I was hoping with all the hype this got on Makezine site it would at least work as advertised. You shouldn’t have to mod something that it is advertised to do….probably wouldn’t buy Gakken kits again.

  6. @Derek – It does work, as I’ve used it myself. But there’s a reason it’s not called an “audio” or “mic” input – try boosting your signal with a battery powered amp or similar before plugging in.

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