Fresh from the Arduino subreddit comes [dataplex]’s 26 string electromagnetic harp. It’s a very cool, ambient instrument that sounds simply phenomenal through the Space Echo and Fender Twin rig [dataplex] has.
There’s not much in the way of build details, but judging from this post [dataplex] made several months ago the instrument works on the same principles as an Ebow. There’s a great prototype video showing the hardware and software. One small voice coil reads each string. A tiny op-amp sends this to another voice coil and back into the string. There’s tons of feedback, but it’s great for an ethereal ambiance.
The prototype is controlled by an Arduino via a computer, but for the final build [dataplex] moved on to a copper/zinc touch interface on the front of the harp.
It’s a very, very cool instrument and we’re waiting patiently for the build details to be released. You can check out the videos of [dataplex]’s work after the break.
[youtube=https://www.youtube.com/watch?v=t8g_9wN4-DU&w=470]
There was a hundred years ago something like this. A piano with the strings energized by a Hammond style generator. It was considered as a way of making electrical music when speakers and tubes (valves) weren’t around yet. Not feedback just excitation from a electromechanical source. This was contemporary with the Telharmonium.
The sound builds up very slowly because the energy gain isn’t much, like he said an op-amp as driver. With an iron core coil and high gain but peak limited 2 watt drive that I get with my steel guitar the attack is much faster even than an Ebow.