DIY Scaled-up EBow-type Feedback Device

there’s also the duofluctus by sergey filatov, which produces sound from two strings being resonated by an alternating magnetic field, created by magnets on a spinning disc, which is then amplified via two pickups for a nice stereo effect.

I was very inspired by the duofluctus when making a sound sculpture built into a pillar together with a friend and collaborator last year. It had no microphones or pickups, only the box for acoustic amplification. this is what is looked like:

here’s what it sounded like:

the speed of the spinning disc enhances different overtones. the duofluctus has a knob which changes the speed. the sculpure I made had an arduino built in which varied the speed on the motor.


WOW! this is a great idea. You could probably also play a normal electric guitar with a similar spinning disk with magnets as a handheld device.

it is, isn’t it! sergey also made a small handheld device he calls magnetor using the same principle which can be seen in this video:


So the magnet is pulling at the strings each time it spins past, causing them to vibrate? Sounds amazing in the video.

exactly. very simple but clever design. glad you like it : )

ghost of thaddeus cahill

What kind of pickups are in the duofluctus, or what would be be suitable?

I have a friend looking to diy something like this.

Wow, I love how the different overtones creep out here and there. Would like to hear more.

don’t know the specifics, but it’s some type of single coil. make your own or buy some cheap ones and experiment!

@DanUK thanks : )
wish i had recorded the sound for a longer period of time, only have a 3 minute recording of it. made another one recently though, with a slightly different design and that didn’t drone but played overtonal bursts at regular interval, but i haven’t documented or recorded it yet. will try to get that done soon!


I have the wond V1, and watched Vo try to get v1 backers to commit to buying the v2. The V1 is a lot of fun with acoustic instruments with the right strings — loud, fast/responsive, and a ton of sound shaping power by just moving position along the string length. But the coils interact way too much with magnetic pickups to be a go-to with those instruments for me. After email communications with them, it became clear that this was a known issue for them that they were happy to brush under the rug during the Kickstarter campaign. I don’t know for others, but I wouldn’t be shocked if the lack of transparency around the V1’s known issues put off other V1 backers from supporting the V2. It felt like good tech, coupled with half baked product development, and an approach to customer trust that just isn’t sustainable with a crowdfunding business model.


That’s a bummer, particularly with something that seems like a cool idea like that.

I guess it’s a bit of a classic, too: crowdfunding isn’t sustainable as a cop-out from the challenge of developing a viable business model, product line, and consumer base.

1 Like

I fianlly managed to get a secondhand Piezothing ex Japanese auction site, charged it up & had a quick play yesterday and am really impressed with what it is capable of. It made light metal trays & biscuit tin lid shreik, but on timpani the resonating feedback of the skin was really beautiful. Varying the overall tuning of the timpani as well as touching the skin and applying pressure made the feedback drift with beautiful lag… I’ll record/video some…

I contacted the maker back in April asking to order a couple of them, and he said another batch was coming but I have never heard of any availability so have emailed him again now - will update this when know more.