[sdiy-interim] MIDI guitar, the hard way

[Gorka Garcia]

Hi Harry,

I am not sure if I understand what you mention about the string/fret switches being monophonic.

Sure there are two contacts per fretted string, but I could decide to only use the higher pitch switch.

My idea is to scan through the strings with a microcontroller by putting a high level on a string and checking which frets are at high level. I will get a reading of two fret/string switches making contact and I will only use the one providing the higher pitch. Would that not work? I basically do not mind about each string being monophonic, that is how the guitar works anyway, but I would obviously not want the whole guitar-thing to be monophonic.

One thing I was reading about which call my attention are optical pickups. How would that work in order to detect the strumming? How diyable is that idea (please remember I am only trying to capture the string strumming).

Thanks all for your comments,

Gorka

--- harrybissell at copper.net wrote:

From: harrybissell at copper.net
To: torpedo at demadrid.com, synth-diy at vermine.org
Subject: RE: [sdiy-interim] MIDI guitar, the hard way
Date: Mon, 26 Mar 2007 15:49:53 -0000

Don't know if this is obvious but your
string / fret switch must be monophonic
(you can only fret one string at a time)

The issue is that the strings make TWO
contacts, one toward the bridge, and another
toward the nut.

Play any chord and you will see that most of them
would short a number of strings across a number
of frets... making an almost undecipherable mess.

Roland has a patent using current transformers
build into the frets that might possibly work well
but would be hell for a DIY approach.  Might use
Hall effect these days, still tough....

I'd look for a old G-Vox hex guitar pickup, used.
Cheapest way I can think of to get the amplitude
sensing...

And if the system is really monophonic... why not use the
main pickups for amplitude ?

Its a really tough problem, that is why it has not been commercially
successful (yet)

H^) harry



>
>
>
>---- Original Message ----
>From: torpedo at demadrid.com
>To: synth-diy at vermine.org
>Subject: RE: [sdiy-interim] MIDI guitar, the hard way
>Date: Mon, 26 Mar 2007 08:10:55 -0700
>
>>So... Now for a crazy idea that hopefully I will be able to work on
>whenever I finish the other 20 projects in the list:
>>
>>I have this korean made Les Paul style guitar which I want to become
>something useful. I thought about different artistic ways of using it
>and finally I realized it was born to be a MIDI guitar controler, but
>not the usual MIDI guitar with expensive Roland pitch to midi
>hardware. My thought was to connect every fret and every string to an
>AVR/PIC microprocessor, creating a matrix of switches between strings
>and frets. That by it self will make of my guitar a pretty cool synth
>controler (I know, no string bending... oh well) however, I will also
>like to be able to sense individual string strumming. I though about
>it and the only solution I found is using an Hex pickup (magnetic or
>piezo). Can you guys think of another solution for detecting
>individual string strumming? hopefully something DIY and cheap? Once
>the guitar/controler is finished, it does not necesary have to sound
>right when the strings are strummed.
>>
>>Would something like this work (from Dave_B in the diystompboxes
>forum):
>>http://davebales.com/me/stompboxStuff/hex_pickup.jpg
>>
>>Notes from Dave_B:
>>"Could it look something like this?  I left out the wires and guitar
>strings for clarity.  The white and gold part is the cut piezo, the
>black part underneath is foam rubber or something similar.  I've seen
>articles about glueing whole peizos to guitars for pickups (and tried
>with some success a long time ago).  If you put these close to the
>strings would it be enough to keep them from triggering notes from
>adjacent strings?"
>>
>>
>>Have in mind that I am not expecting to capture sound out of the
>piezos, only the amplitude of the strumming.
>>
>>Thanks,
>>
>>Gorka
>>
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