Before I go into detail, let me say that this isn't very exciting - one day I shall
circuit bend my synth the seven shades of terror, but this isn't that. I put a cable on my synth, and added a switch to toggle between the built in speaker and the line out - simple as. But I'm a little busy to pull out all my old design work, and a little too being marked to show any new design work.
I've been trying to build a synth rig for about 5 years now. I even got so far as trying to implement MIDI on an AVR at one point, and built a wooden rig from 2by4s to house a BCO (bike controlled oscillator). But to this date, that hasn't been finished. And when I started playing bass 18 months ago, that took precidence - any synth rig is probably going to be controlled from my bass now.
But that didn't stop my buying this little synth when I saw it in a charity shop. At £3, it was a bargain - the kind of bargain where the 4 AA batteries cost as much as the equipment! It's a tiny little keyboard, some might call it a childs toy, with miniature keys. And over the past year it's served me well, helping pick out melodies and still running of the first set of batteries.
The Casio SA series was a set of little keyboards using wavetable synthesis, in which two sounds are added together variably out of phase, and an envelope added on top. The keyboards were all very similar - in fact you can turn most of them into any of the others with only small modifications, such as extra buttons.
Mine has a space for a headphone jack, but my electronics lab isn't what it used to be, so I just patched the line-out cable (left over from a recent
headphone mod) straight off the speaker send, and then made a little hole for the cable and switch, used to swap from the internal speaker to the line out.
As far as level goes, it's roughly comparable with my bass - points to anyone who wants to explain (to yourself, not me or my readers) how the impedance matching works. I need to add a small resistor somewhere to stop the line out buzzing when disconnected - still deciding where would be best, but there's no rush, because I'm fresh out of resistors anyway.
There's a bunch of photos below of the build in progress, and a pair of videos of the new line out in action, including it plugged into the effects rig for my bass.
Two keyboards
The switch, gracefully mounted!
Before I happened
After I happened
