When the electric guitar was first produced in the 1930s, there was some skepticism among musicians as to whether or not this instrument would have lasting impact or be a flash-in-the-pan novelty. Since this was more than a decade before the invention of the transistor, it would have been hard then to imagine the possibilities that a musician nowadays would have with modern technology to shape the sound of an instrument like this. People are still innovating in this space as well as new technology appears, like [Gary Rigg] who has added a few extra degrees of freedom to a guitar effects pedal.
A traditional expression pedal, like a wah-wah pedal, uses a single motion to change an aspect of the sound of the guitar, and is generally controlled with the musician’s foot. [Gary]’s pedal, on the other hand, can be manipulated in three different ways to control separate elements of the instrument’s sound. It can be pitched forward and back like a normal effects pedal, but also rolled side-to-side and twisted around its yaw axis. The pedal has a built-in IMU to measure the various position changes of the pedal, which is then translated by an RP2040 microcontroller to a MIDI signal which controls the three different aspects of the sound digitally.
While the yaw motion might be difficult for a guitarist to create with their foot while playing, the idea for this pedal is still excellent. Adding in a few more degrees of freedom gives the musician more immediate control over the sound of their instrument and opens up ways of playing that might not be possible or easy with multiple pedals, with the MIDI allowing for versatility that might not be available in many analog effects pedals. Not every pedal needs MIDI though; with the help of a Teensy this digital guitar pedal has all its effects built into a self-contained package.
Wrong side up, usb should be on bottom.
The electronics are all in the top part. See: the video.
I assume they meant from a design perspective; I’d worry about stresses on the cord and port, or that it would get snagged and pulled out or even just moved accidentally. I had to look up what an IMU is, at which point I realized the sensor has to be in the moving portion, so there’s not going to be an easy solution.
it’s definitely neat! lots of possibilities. i used to be really attracted to this sort of project myself
but as i’ve started to approach music from a more instrumentalist angle than a technologist one, i have really become an analog snob, and i’m especially wary of IMU as an input device. there’s going to be some amount of noise / jitter, and also quantization / stairstep effects. these aren’t necessarily fatal to musicality. in fact, a lot of times artists inentionally use quantization. but to me, an instrument’s expressivity should be roughly instant and continuously-varying. an electronic instrument is fine but one that introduces quantization rubs me the wrong way.
otoh, for all i know the imu is powerful enough that you can’t notice the defects. and if you’re like changing the effect levels between songs instead of doing it to shape individual notes, you wouldn’t notice even if it did.
There is no way, when coupled to any usable filter/effect, that you’d notice stepping even at a relatively low resolution of 10 bits. Most DAWs and MIDI-controlled hardware work with 8-bit parameters, and often halving that to just 7 bits/128 steps.
My issue with using an IMU for this is the difficulty in returning to zero. The tilt and roll you could maybe work out by referencing gravity, but I don’t see any reliable way to get the yaw to reliably keep its position, especially when it’s near level with the ground. I can see why it was done this way, though. Using potentiometers/optical encoders would make things quite a bit more difficult to piece together.
IMUs are generally six-axis devices, using a 3-axis accelerometer for rotation sensing and an 3-axis magnetometer for orientation, which means that if you know roughly where on the planet you are on the planet, you can figure out which way you’re pointing.
Also, if you look at the video, yaw is referenced to the base of the unit, so it doesn’t even need the magnetometer.
just to be clear, i’m stating skepticism of all digital workflows for real-time control of a musical instrument. i’d love to hear a side by side comparison of a ‘real’ wah wah pedal and a midi bandpass pedal. i’d be surprised if you can’t tell the difference as a listener. not sure how to go about this experience of being surprised though :)
it’s like breath-controllers (midi saxomophone). they’re surprisingly good. they bring advantages. but are they expressive like a wind instrument?
You would when the light bulb in the “real” wah pedal burnt out or the cloth flap broke.
I’d say experience musicians especially in jazz or heavily syncopated styles do hear this
Becouse the tiniest hairs of time is what goes on in one who plays that
You rub a bit there where the daw precision starts feeling obnoxoius
And you are rubbing something in the compas in a musicians head
I dont expect no one believes that, except folks used to overlapping metrics and swinging them
Jimi Hendrix had a x/y pedal custom made it yawed. The poor stability of the ankle joint in the side to side roll like what happens when you try to stand on ice skates (ouch) would not work as well as yaw. I made a dual pot dual motion swell pedal for my keyboards. Think like your toe is acting like a joystick, rather instinctive.
Actually this project is not about signal processing but midi CC messages, great but unlikely to be in an guitarists old skool pedalboard. One of the newer DSP boards if it can handle triple CC, yes.
The first 3 electric guitars were steel slide style. The new style was all the rage from Hawaiian to the blues and what became country. In 1915 Hawaiian music was featured at a worlds fair on west coast, where would we be if that show hadn’t happened. In 2 years it was all over the popular music.
Yaw does work by foot. There is neoprene rubber on the top and bottom of the unit. Slightest bit of downward pressure it sticks to the floor like glue.
BrightBlueJim is correct. Yaw is referenced to the base and there is no magnometer. Should the base be moved / rotated there’s a small button to recenter.
Very neat, I’ve been working on something that will need a similar device soon.
I had been thinking of repurposing the guts of a 6 DOF game controller or simply gaffer’s taping one to the back of my guitar at a proof of concept , specific wireless controller suggestions would be welcomed. Smallness is good, actual ergonomics and utility as a game controller is unimportant, glitches are very bad.
Back to this
This would be a lot better if it had a Bluetooth or other wireless connection. Also, why a pedal? Why not make it wearable or attachable to other arbitrary objects like:
The performer’s shoe
The mic stand
The guitar itself
Or any of the other things that guitarists move around. Think of as changing affect to effect!