OysterRock wrote:Its not that simple. When you play a string on a guitar the sound isn't a pure sine wave, it contains a lot of harmonics.
Fair enough. A guitar string does not vibrate merely up and down, but also side to side, and also vibrates in a circular motion... all at different places along the string, depending on the pluck. I can dig it. Thank you for the clarification.
OysterRock wrote:If it were a pure sine wave your guitar would sound like an organ!
None of my electric pianos sound like organs, but I understand what you're getting at.
OysterRock wrote:That is why guitars signals are so hard to track. Its hard to distingush the fundamental frequency from all the other harmonics (especially when playing chords) coupled with the fact that the guitar signal is not a periodic signal and is always changing because the player is playing fast.
None of the analog pitch-to-voltage devices I'm aware of were capable of tracking chords.
The problem with guitar tracking was more about the fact that guitarists were unwilling to or incapable of playing in the way the pitch-to-voltage converter needed them to play. Expressive guitar playing does not lend itself to pitch-tracking.
OysterRock wrote:coupled with the fact that the guitar signal is not a periodic signal and is always changing because the player is playing fast.
If a non-periodic signal is impossible or even difficult to track, I would wonder a number of things... including, why so many companies invested time, money, and effort in creating guitar synthesizers, why it is that it is possible to play a decent guitar synthesizer with a guitar successfully (although with effort), and how it was that the Korg MS-20 was able to track a human voice which is completely non-periodic, possessing of a great deal of harmonics, and even less pitch-stable than a guitar.
OysterRock wrote:This is exactly my point. If you are singing a note into the P2CV converter at a constant pitch and amplitude, then you are effectively inputting a periodic signal (sine, square, triangle etc are periodic signals, guitar signals are not. Periodic signals are signals that repeat over a certain period) which is exactly what P2CV converters track well!
I don't think I made myself very clear, and I'm sorry about that! I didn't mean to suggest that when one sang ONE NOTE at a CONSTANT PITCH, the CV tracking would work... although it would be hilarious if I were asserting that as support for the notion that pitch-to-voltage converters were effective. ; )
Let me reword it: The times where the pitch-to-voltage converter struggled were times when the volume of the voice dropped too low, or when the pitch of the voice varied quickly over a range of random notes. In the case of the pitch issue, this is not something a guitar string would do, unless you were rapidly sliding your finger back and forth among a few frets, or jiggling a whammy bar. Likewise, with the volume issue... you would have to pick the string VERY gently for the drop out I'm talking about with the voice to occur.
Secondly, despite my degree in vocal education, I am unable to consistently produce periodic signals with my voice. ; ) The larynx, like the guitar string, is capable of producing a great deal of harmonics. The pitch tracking I'm talking about having occurred with the MS-20 was not a situation where an effort to produce pure or periodic waveforms was occurring. Not only that, but there were a variety of non-consecutive pitches and glissandos that occurred, and were tracked.
Thirdly, if pitch-to-voltage converters were only effective with periodic signals, they would only be effective with electronic instruments... as most acoustic instruments (perhaps excepting electric pianos) produce harmonic-rich and waveform-varied signals.
Now, I'm sure there are many guitar players who would say "That is absolutely correct!" But, again... I have to say (and there is plenty of recorded proof by famous artists, let alone infamous ones) that it is possible to get a GOOD pitch-to-voltage tracker to track your guitar playing... provided you played in a way that did not interfere with the tracking...(without fast runs, without sudden dynamic variation, without pitch vagueness) and this manner of playing was and is anathema to any expressive guitar player.
I think the main problem with analog guitar synthesizers was/is:
Why would a guitar player want to sound like a monophonic synthesizer? If you're going to be playing relatively slow melodies, why not just plunk it out on a synthesizer? This logic was apparently lost on David Friend. ; )
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