Laser harps aren’t quite a right of passage, in that not everyone builds them, but it’s likely everyone at least contemplates building one at one time or another. We’re lucky that [Derrick] a.k.a. [DJ Baja Blast] didn’t stop at contemplating, and even luckier that he put together a full write-up for his tricked out laser harp — because this is a fascinating build, with features we’ve never seen in one place before.

First of all, the harp! Lasers, photodiodes, done, right? Not here! [DJ Baja Blast] kept it analog with photoresistors so that he could measure the rise and fall of the voltage as the laser light is occluded by the player’s hands — thus you can moderate the volume via faster, louder and quieter, slower plucks. More unique is the inclusion of an accelerometer. What can you do with an accelerometer in a harp? Well, here it’s being used as a tilt sensor, with the tilt acting as a control to ‘bend’ the note as it sounds, tuning it flat or sharp or altering it any other way you choose to define in software. There’s also an ultrasonic distance sensor so you can do the same thing — or any other thing, there’s no shortage of effects to chose from — theremin-style, and an encoder wheel sits on the side, so that’s five extra inputs beyond selecting a note by blocking a laser diode. Unless you count the optional looper pedal input, or the aux in.

All these inputs are driving a Teensy 4.1 microcontroller, which has the grunt for just about any synthesis or sampling, though right now [DJ Baja Blast] is sticking with the Karplus-Strong string synthesis algorithm. The Teensy can drive an onboard speaker but also offers MIDI out. Eventually he does intend to add more. Last but not least, we cannot forget that he’s plumbed this instrument to hook to a fog machine. Which makes for a visually engaging performance, and probably helps a lot when you’re learning where the laser ‘strings’ are.

The whole thing is handsomely put together with cherry and walnut. Does it sound as good as it looks? Listen to it in action in the demo video below, and judge for yourself! If you want to build your own you can grab the files on GitHub.

This is hardly the first laser harp we’ve seen, or even the first to use a Teensy, but it’s certainly got the most options to spice up a performance. It’s got to be a baja blast to play.