I said it was addictive

Well… since last post things got wild as usual

Yes, a simple bass would be great. And yes, the metallophone/glockenspiel could be perfected. And yes, most bands use more than 4 percussion instruments in their musics so the Percussion Kit could be extended a bit… and since some MIDI files include lyrics on a metadata track why not trying Text To Speech and have a singer? And what about that last year funny finding of doing music with pneumatics valves?

So The Mindy Python’s Confined Circus band has born.

And also yes, the software part is getting complex day after day. Thank god for open source and search engines.

So after having a basic 4-intrument Percussion Kit sorted out I decided to try a LEGO one-string instrument. Nothing fancy, just the basics: just a string and a resonance box:

It worked so I kept improving it… added an arm (neck), a longer string, some gear to adjust the tension… and got something that sounded on the bass range:

Then I reinforced the whole thing so I could play without dismantling it:

at this stage I was using a 300 cm Technic string, folded in two and twisted to increase the weight (weight, tension and length decide the note we get).

I wanted a slightly lower pitch and also a fret board with enough precision to mark 8 to 12 tones so I decided to increase the neck a bit but had to reinforce it a lot because tension was already too much. I ended with a 111 cm fret length:

Another advantage of such a long neck was having enough space to add some motors. So with a Technic Control+ hub I could have 1 motor to strum the string and 3 motors to press the string against the fret board:

I chose E, G, A and C because those were the notes used on Queen’s “Another one bites the dust’.

The code part shares most of the code of the Percussion Kit except that for the bass I don’t just map each note to a single motor action, I need to store on the hub the current state of the “fingers” to move the necessary ones for each new note command (for instance: if the bass is instructed to play ‘C’ it lowers the finger on the ‘C’ fret… if another ‘C’ follows, there is no need to move the finger but if it is a lower pitch note (like ‘E’) it needs to move the ‘C’ finger up and move the ‘E’ finger down, wait a bit for the finger to reach position and then strum the string.

With this robotic bass I am still facing some issues while strumming the string… it doesn’t sound the same as when using my fingers… and since I don’t know how to play a bass, that means a lot. I already tried hammering it instead but no luck… will probably need to find a mechanical design that moves the pick in a more complex way.

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