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ElektroCaster

An open, modular guitar-design with some nifty features.

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Compared to this whole world of electronic sound devices like eurorack-modules, drummashines and all this innovative stuff from big and small companies, the electric guitar market looks a little bit boring.

I play guitar but I also like those new ways of making music and I believe that a guitar could integrate great into an electronic music setup. It just needs a kind of redesign - what's technically possible shoud be done, as long as it stays to be a guitar.

Here is my proposal for an open, modular guitar-synth-design with some nifty features to make modern music.

Motivation

I have spent much time in the past to hack guitars, adding robotic elements to them, messing with control interfaces and audio effects. But I allways did this in a non-destructive way, as I didn't wanted to do something to my babys I couldn't redo. One thing I always wanted to have, but never really achieved on this premise was an illuminated fretboard to display all kinds of information, like scales and sequencers. This problem is the main driver of the project and most of my thinking about building this guitar was how to do this.

As I'm not a carpenter but more an allround maker with typical maker tools like a 3d-printer and a cnc-router, the main challenge was to commit to a concept of build this guitar with those tools I have.

Design Goals

Before I start to decribe the build process in the project logs, here are some specs and design goals I have/had in mind when building the ElekroCaster. This list will evolve.

  • Maker friendly construction (3d-printer, CNC-Router, Vslots)
  • Modular construction and easy access to the electronics to make it a smooth prototyping platform
  • Parametric OpenScad modelling (changable string count, scale, space between strings,...)
  • playable like a normal electric guitar,
  • Fully controllable RGB-Led-iluminated Fretboard
  • Touch-sensing-frets
  • Long scale (700mm) for low tunings
  • Two micros, one for audio an one for everything else.
  • Per string signal path
    • hexaphonic pickup
    • hex-preamp
    • multichannel codec (6* adc, 8*dac)
    • Teensy 3.6 microcontroller

Possible applications:

Firstly, the ElektroCaster can be played like a normal (baritone-)guitar (which in itself I'm quite proud of). It's neck is admittedly kind of thick and I whish there would be thinner v-slots available (15x15 would be nice). But all in all, I do enjoy playing it. 

Let's talk about what the ElektroCaster can do what others can't, by quickly sketch some applications. Some of them I allready have implemented and others that I'm sure I will be able to implement.

Music making

In the video below you can see me playing a sequencer projected to the fretboard, which is programmed by using the touch-sensing frets. It works not perfect yet, but I'm making good progress to improve on that. Notice that the strings are muted and do only sound when the string touches a fret and the sequencer hits an activated step. The strings are hit with the blue device next to the pickup which basically consists of 6 solenoids. I call it kickup. More about that in the so called project log. 






This is a pretty rough demo an implementation, but I think it shows which possibillities are opend up by this combination of sensing led-frets, hexaphonic signal path with dsp and robotic elements like the kickup. Next step to improve the sequencer is to use envelopes to switch the strings on and off more smoothely.

Education

some Ideas on this topic:

  • learning a scale:
    • display the scale on the fretboard. Highlight important intervals like the third and fifth by different colors
    • sens whether a wrong note is played and give feedbacke, e.g by
      • muting the string on which the note was played
      • play a particular sound
  • play one note and immediatly see all other notes of the same value on the fretboard to look for alternative ways to play something
  • teach guitar
    • connect two ElektroCasters, one for the teacher and on for the student.
      • Display notes the teacher plays on his guitar on the on fretboard of the student to help him find the next notes

In the Video below you see me improvising along a b-major-scale. It's a bit hard to see, but there are different colors for different intervalls: The root is red, the third is green, the fifth blue and the seventh pink. The second, fourth and the sixth are darker and white. Although I know how to play a major scale over the entire fretboard, it's a really interesting experience - It feels releaving not think about the...

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  • The MultEBow

    Frank Piesik10/13/2018 at 07:42 0 comments

    "The EBow is a battery-powered electronic device for playing the electric guitar. The EBow uses a pickup – inductive string driver – feedback circuit, including a sensor coil, driver coil, and amplifier, to induce forced string vibrations. The EBow is monophonic, and drives one string at a time, producing a sound reminiscent of using a bow on the strings." (Wikipedia)

    The idea of the MultiBow, which I'm currently trying to realize, builds on this concept. It's essentially six EBows firmly installed under the strings. The allready installed hex-pickup serves as sensor coils and the driver coils are integrated with small class-d amplifiers into another pickup looking package. So the six signals from the pickup are going throug The Teensy-audio-board I use. It has 8 output-channels and I do only need one or two for the main output. One idea was to have additional discrete outputs for each string to process them externally. But using them as part of the MultiBow does make more sense to me, as it opens up the possebillity to modify the feedback signal to alter the effect on the strings (see moog guitar).

    Here is a little demo video to proof the concept:

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  • The KickUp

    Frank Piesik10/10/2018 at 12:41 0 comments

    The KickUp is an actuator which includes 6 solenoids and a mosfet driver. It's used to hit the srtings from beneath - just the opposite of a pickup. Now the ElektroCaster can play semi-automatically (you still have to use the left hand). See the the KickUp in action in the sequencer video on the details page!  

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  • Connection and Communication

    Frank Piesik10/08/2018 at 10:15 0 comments

    Since this guitar is intended to be used in an ectronic music environment, it has to communicate with the rest of the gear, at least to get a clock signal on which it can synchronise it's actions.


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  • Body-Neck-Construction

    Frank Piesik10/08/2018 at 09:35 0 comments

    I used three different types of components to build the basic shape of the guitar: 3d-printed parts, 20*20 VSlot profiles and plywood.

    My printer (Creality CR10S4) has build volume of 40*40*40cm. Beeing able to print the shape of a guitar body was the main reason I went for this big printer.

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  • Audio-Hardware

    Frank Piesik10/08/2018 at 09:31 0 comments

    Here are some design goals for the audio part:

    • Discrecete audio path for each string to allow for independent audio manipulation.
    • Audio processing happens within the guitar, not on an external computer.
    • Latency under 5 milliseconds.
    • low power consumption to allow for battery operation.
    Read more »

  • Touch-Sensitive Frets

    Frank Piesik10/08/2018 at 08:26 0 comments

    An iluminated fretboad is nice to have, but making the corresponding frets touch-sensitive, the fretboard becomes a powerful userinterface.


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  • The Led-Fretboard

    Frank Piesik10/07/2018 at 19:33 0 comments


    Thankfully, we live in the age of smart leds, because the WS2812B make the task of putting over a hundred led into a thin fretboard much easier. I cut an led stripe into its pieces and usesd the template on the left to arrange them and soldering them back together.

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View all 7 project logs

  • 1
    01 Preface

    If you want to build the ElektroCaster, here are some aspects you want to consider before you start:

    • This isn't for somebody who just want‘s to get the needed parts and assemble it like a diy-guitar-kit (yet). There will be some hurdles to take and difficult manual   labor to make.
    • Although this is a working prototype, this project is still (and may allways will be)  work in progress. Software and interface are hardly developed yet. 
    • Think of it like a protoyping platform: wack in a new headstock with robotic          tuning features, try a new actuator beneath the strings or change the neck over an improved one – thanks to the modular design, all of this can be relatively       easy achieved.
    • There is not "the one ElektroCaster". It's parametrically designed in OpenScad, which is why many features can be changed: The number of the strings, the         length of the scale, the spacing between the strings (at neck and bridge             positions) or the number of frets can all be edited whithin the parameters.scad     file. That means, you could also make a small four-string-ukulele-version out of it.


    Tools that you might not have:

    • A big 3d-printer with 400x400x400 build volume, because there are many big  parts, which can't be split easily.
    • A cnc-router or laser-cutter wtih a build size bigger than the body (322x396mm).
    • A method to make the pcbs, I used my cnc-router. 
  • 2
    02 The Slot-Body

    The core of the ElektroCaster is made of aluminum V-Slot profiles. I started whith a v-slot-starter-kit from RatRig, which I do recommend to get.

    For the slot-frame you‘ll need the following parts:

    • 3 x 50cm, 2020 v-slot profiles
    • 6 x M5, 40mm screws
    • 4 x M5 t-nuts

    And this tools:

    • Saw
    • Screwdriver
    • Tab to make M5 threads.

    1) Cut the profiles so that you end up whith the following lengths: 2 x 50cm(D), 2 x 25   cm(A), 4 x 12.5(B,C,E).

    2) Drill some 5mm holes to screw the parts A,B,C,D together. My v-slots allredy              came with threads on both ends but since you cut them, you‘ll need to tab some      threads to the A parts.

    3) Drill holes near the ends of E and use t-nuts to connect them to A and D. There        are no exact measures how to put them. They‘ll probably need to be adjusted          when mounting the printed body in the next step (which is no problem since the n    uts can be easily moved).

  • 3
    03 Print The Body-Frame

    1) Print the body.stl file (/hardware/mechanical/stl/body.stl). I used a .6mm nozzle,          .8mm extrusion width an .3mm layer height.

    2) Attach the printed body-frame to the slot-body using M5 screws and t-nuts. The       screws need to be cut to length.

    One screw doesn't need a t-nut as it's directly put into the slot-body. This screw is   one of those you allready used in step 2. I don't think this is really needed so I may   remove this in future versions.

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Discussions

Mark Carew wrote 10/11/2018 at 14:53 point

Just want to chime in to say Frank this is an awesome build brother! Thank you for sharing hope your able to bring this to the masses for teaching.

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z26 wrote 10/10/2018 at 21:54 point

Neat, I'm working on something very similar but I want to do an harp instead. (I'm not as advanced in the project as you are).  Single coil pickups can be found as low as 3$ online, so I was thinking of using one for each individual string.  So far my arduino uno can directly listen to the pickup, without any extra components.  The audio isn't good quality, but it's clear enough that I'll be able to play a guitar hero clone with the harp.

I'm still debating what I will replace the uno with.  Since I'll have at least 12 pickups, I assume I'll need two boards (2x the cost).  I don't need as much processing power than you (I want to plug in a pc, not an amp) but I do wonder what kind of quality I could get with a teensy alone (no board).

Alternatively, I could try multiplexing 2 pickups per pin which would half the sample rate of each one.  While the loss of quality of doing so is quite drastic for percussive instruments, it seems much less pronounced for guitar strings.

Good luck with your project

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Brandon wrote 10/08/2018 at 18:58 point

Just wanted to chime in that this is sooo cool!

One thing that came to mind (from someone who has intermittently tried to learn the guitar) is to leverage this type of system for straight-up teaching of the guitar.

Also, I want to productize this something real-bad.  Do you have any interest in doing that?

Thoughts?

Again, so sweet!

  Are you sure? yes | no

Frank Piesik wrote 10/09/2018 at 08:08 point

Thanks!

Yes, the educational aspects of this project are very important to me too. I already have some ideas on how I want to use this for teaching...

I think this could be tailored for just this purpose and be quite inexpensive to produce. So yes, I'm basically interested to make a product out of this, but there are no concrete plans yet.

  Are you sure? yes | no

Brandon wrote 10/10/2018 at 04:16 point

Sounds good.  Well for what it's worth I'd be happy to help out.  I think this concept/product could sell well.

How I could potentially help:
1.  I recently met w/ an investment broker over an idea I'm currently prototyping.  He gave me the skinny on what all is needed in a pitch deck, and what will/won't fly.  Based on what you have I think it's enough to throw a pitch deck together and get funded to make this into a product.  (That, or Kickstarter.)

2.  I'm an EE.  So I can help productize that side.

3.  I happen to have a buddy who last year started a Industrial Design and Mechanical Engineering services company, so his business could definitely take the mechanical side through product.

Anyways, here if interested.  In the meantime I'm going to continue to do a slow/cumbersome job of writing Swift code (to make the proof of concept of my idea), until I can convince someone to do it for me.  ;-)

Cheers!

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