[sdiy] MIDI to CV question - no Triggers?

[D A F]

Well, I don't normally use MIDI, so I'm not totally sure that I know what we're talking about here.  The Yamaha G50 apparently has three MIDI "modes":  "Multi-Channel", "Single-Channel Polyphonic", and "Monophonic".  From what I understand of this, in Multi mode, it does what you are talking about - sends data from each string over a unique MIDI channel.  In Single-channel Poly mode, I think it does the merging for you.  Obviously the Mono mode just allows one note/string at a time to be sounded.  So I guess in relation to using the guitar and the G50 with a MIDI-CV converter, I would only have to worry about the Trigger question in Single Channel Poly mode.  But that still doesnt answer the question of how the converter interprets a sequence of events in which one note is on and another note on is recieved.  I.E., how does it turn this sequence of MIDI events into analog control signals?  Thats what Im really after.  After all, I would eventually be using the converter for keyboard use as well - not just with the Yamaha guitar controller.  

Dave



  ----- Original Message ----- 
  From: Michael Bacich 
  To: D A F 
  Sent: Saturday, March 04, 2006 3:05 PM
  Subject: Re: [sdiy] MIDI to CV question - no Triggers?




  On Mar 4, 2006, at 9:51 AM, D A F wrote:


    Yes, I guess the problem is: What happens when you are holding one note and

    then press down a second note without letting the first one up?



  This would not be an issue when using the MIDI-CV with a polyphonic MIDI guitar controller.  Although the guitar is a six-note polyphonic instrument, guitar strings are inherently monophonic.  That is to say, on a guitar,  it is not possible to play two notes simultaneously on one string.  Or potting it another way, you can't "press down a second note without letting the first one up".  


  Typical guitar-to-MIDI controllers (such as the Yamaha G50 and the Roland GR units) transmit each string's note information on a separate MIDI channel, which would necessitate the use of a separate monophonic MIDI-CV converter for each string.  Such a system would also require hardware for six complete analog synthesizer voices.  This may explain why we don't often see people using guitars as controllers for their analog synth gear.


  If you wish to use the guitar to play a monophonic analog system, you will have two choices:  Either you must restrict yourself to playing on only one string, or you must re-channelize the six-channel MIDI info coming from the guitar so that it all comes out on the same MIDI channel.  This could be done with some kind of external MIDI processing device, such as a MOTU MIDI Time Piece II.  However, this would necessarily open up a stinky can of Pandora's Worms, in terms of some potential MIDI problems and some note and trigger assignment problems -- for instance:  What happens if you play two notes at once?  What happens if you play a note, then the same note on two different strings?  What if you don't completely release the first note before hitting the next?  Which note takes Note-On and/or Note-OFF precedence?  Which note's Velocity takes precedence?  What if you bend a note or notes? And getting back to the original question, what happens with triggers and gates if you press a second note without letting the first one up?  ...there are other potential problems, too.


  Harry Bissell has opened that can of worms many times, and has come up with various solutions for most of the inherent problems -- none of them involving MIDI, though.  Check out his "Muffy" guitar to CV converter for more insight:


  http://www.bitshifted.com/SDIY2004/muffy.asp


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