The Harmonicon

Polyphonic Synthesizer
loudspeakerSound 1 spooky.mp3
loudspeakerSound 2 Ghost.mp3
loudspeakerSound 3 sad.mp3
loudspeakerSound 4 horror.mp3

This is a polyphonic synthesizer. It was the hardest of all my machines to make because there is a separate synth circuit for every note on the keyboard. The synth circuits are made from; 22 oscillators+octave dividers from early 70s Yamaha organs, 88 square wave to sawtooth converters, 88 envelope generators, 88 VCAs, 88 state variable filters, 88 LED drivers.

What does that block of LEDs do

If you look at the top photo, above the keyboard there is a cluster of LEDs. The LEDs are a representation of the keyboard and each LED outputs a note from the keyboard. I use a hand held light sensor to pickup the signal, and turn it into sound. You can play a chord on the keyboard and use the light sensor to fade from one note to another.


I think I damaged my eyesight making it because of all the hours spent staring at tiny components.


The filters

Each of the 88 notes has it's own filter. The filters are tuned to the note to which they are attached. I guess this is similar to a vibraphone with it's pipe resonators tuned to each note, only with this synthesizer they can all be swept together using one fader. You can hear the polyphonic filter sweep at the beginning of this sound.

loudspeakerSound 1 spooky.mp3

Just Intonation

The tuning

Most instruments we use today are tuned in equal temperament. This one is tuned in Just Intonation. You may think that my system looks complicated but it is tuned to simple frequency ratios, the same ones that have been used by musicians for thousands of years. They are so natural that I was able to tune them all by ear, and I've got a terrible sense of pitch, I can't even sing Happy Birthday in tune.

Most musicians don't understand the science of tuning and are unaware of just intonation, but to the ears the difference is obvious. Listen to my sound files. You can hear something special in the sound even though I am not playing anything that special.

loudspeakerSound 1 spooky.mp3
loudspeakerSound 2 sad.mp3
loudspeakerSound 3 horror.mp3
Major Scale

Major scale

Minor Scale

Minor scale

When I finished making it I was very pleased with how rich the sound was. I don't really know why it sounds so good!