Rocktave Tracking

[john.hostetter]

Hello everyone. I recently finished a Rocktave divider a la the layout found on GGG:
http://www.generalguitargadgets.com/projects/22-octave/130-rocktave-divider
Everything works great, including the mod for multiple divisions. The only problem is that I play a guitar tuned down to C#. This means that anything below about the 7th fret has pretty inconsistent tracking and inspires sputtering. I installed a pot to adjust the resistance to R22, and this helped a little.

After searching the forum I came across hints that there are mods for the rocktave that could respond to bassier input:
http://www.diystompboxes.com/smfforum/index.php?topic=61803.0

Anyone care to elaborate?

Thanks!

[Mark Hammer]

My great insight into octave division came with the closer examination of a unit briefly made by Guild that provided 6 independent octave dividers and a proprietary divided pickup, such that you could get polyphonic octave division.  Because of the sheer size of the pickup, you could never get it anywhere near close enough to the bridge to provide bleed-proof tracking.  One string would constantly bleed into the adjacent polepiece and cause mistracking.  Then one day, someone, may have even been RickL, noted that such units would have likely been played with heavier gauge, and perhaps even flatwound, strings at the time of their release.  Stiffer strings would have resulted i less bleedthrough.



Generally speaking, the higher up you fret, the stiffer the string becomes.  Now while we're not talking about divided pickups and string-to-string blurring here, that stiffness still has a few implilcations.  One is that, with increasing stiffness, fundamental predominates and harmonics recede.  Another is that the string is less likely to deviate in pitch.  Finally, I suspect there are fewer moments where the string "beats" or where the amplitude fluctuates above and below the threshold for detection, simply because of the summing of harmonics.

The net result is that mistracking is extremely common at lowest frets, regardless of the pedal (though I can't speak for digital boxes).  Though I have to confess, I rarely hear anything from folks saying "I generally use .013 through .058 flatwound on a short scale guitar and my octave divider works terrific!".

The tracking-related features of the Rocktave are essentially those related to providing a fairly consistent amplitude, and fading out the divided signal before the tracking becomes unreliable.  There is nothing about it that really addresses the things that would normally be improved upon by using stiffer strings.  One thing I suppose you could do is provide some filtering to put the harmonis further in the background.  That might help a bit.

[john.hostetter]

Ohhhhhh. I guess I wasn't clear on how dividers worked. It definitely confused me when it worked better on the neck pickup. I actually just played with it for about 3 hours tonight and I am pretty darned impressed with it. I may look into your filtering suggestion, but until then I'll stay on the stiff side of the strings Thanks for enlightening me Mark!

[Mark Hammer]

Alternatively, consider a digital pedal of some sort.  Not only do they often provide polyphonic octave division, but they track better too.