String Driver Note Calibration and Balance


The Virtuoso Violin has a note range which extends from G2 to G5, the same as a real violin.  Each note is adjustable in drive (volume) from 0 to 127. 


There are a number of reasons why note drive may need to be adjusted from note to note.  For example, the higher notes need more drive to produce the same volume as a mid or lower note.  A note which is sympathetic with the instrument may need to be turned down to match the surrounding notes.  Or a weak note may need to be turned up.  As there is only the single “string” (blade) some notes ring truer than others.  The Note Calibration and Balance system compensates for these differences to create a smooth scale throughout the range of the violin.



Running the Note Calibration and Balance MIDI Software


- Attach a computer to the violin via a MIDI cable.

- Load the instrument’s Note Calibration and Balance MIDI File into the computer’s MIDI Sequencing Program (such as Cakewalk or Performer).  Typically the MIDI File will have a name like Cal_105_070602.  In this example the Cal = Calibration, the 105 = violin #5, and 070602 is the date.

- Hit PLAY to run the calibration (note balance) scale. 


(See below for instructions on using the calibration software to calibrate the violin.)


Here is a typical Calibration MIDI File for reference.  You can use this to build a custom drive curve.  (Use “Save As” feature of MIDI File Player to save file to disk.)



How It Works


Controller 87 opens the violin EPROM to write new values.


Controller 87 = ON = OnLine (ready to play)

Controller 87 = OFF = OffLine (ready to write new note balance numbers)


The opening scale in the software MIDI file (measures 1-40) begins with a controller #87 set to 0 (off), which takes the violin OffLine and allows writing to the EPROM.


Note volume balance numbers (controller #27) can be changed for each of the violin’s 37 notes.  For example, if C3 is set to Controller #27 = 50, then changing Controller #27 to 55 for that note will make it play louder during a performance.  While changing Controller #27 to 45 will make it play softer.  (Note that simply changing the value does not write the new value to the EPROM.  After the number is changed, the scale must be played again to write the new number to memory.)


By playing the scale again, these new values are written to the violin’s RAM where they are stored for future performance.  They will not change unless a new value is entered for the note and the scale played again.


Measure 40 contains a Controller #87 = 127 (ON) which closes the memory and takes the instrument back OnLine, making it ready for performance.


The scales starting at measure 50 are useful for evaluating note balance.  Like with a professional piano tuner, practice makes perfect, and it helps to have a good ear.



Why Note Balance is Needed


Each violin is constructed slightly differently and will require its own custom note balance curve.  Cal_101 (Violin #1) and Cal_103 (Violin #3) are stored here at PML for future reference.


Whenever a violin is built, rebuilt, modified, regulated or otherwise worked on, it may need rebalancing.  The technician that works on that particular violin should have the instrument’s note balance curve and means for playing it into the violin and adjusting the values (ie: a computer).


Alternatively, note balance curves can be created from the “standard” note balance curve file by an experienced technician without too much difficulty.


Note: A standard note balance curve of x=50 (ie: each note = 50 drive) is automatically written to memory when the instrument is started for the first time and the memory is blank.  In addition a standard default bow angle is also written.



How to Set Note Volume Balance


I find it useful to have a scale chart available when running the calibration scale.  I use UP or DOWN arrows in pencil to indicate whether the note drive for a particular note should be raised or lowered.  Then I can make all the changes at once to the #27 controllers in the scale, then run the scale again to evaluate.  You will hear the new values take effect as the scale is running.


Repeat this process over and over until the end scales (measure 50) sound smooth and balanced.


Individual notes can be changed using the above methods.  (In fact, this is how I typically use the software.)  But make sure to always run the scale from the beginning to the end to open the memory and close it with the #87 controller.  Alternatively, I often “leave the memory open” as I continue to adjust a single note or series of notes, then “close the memory” when I am finished by playing the entire scale. 


Obviously, you can open the memory at any time by simply playing a controller #87 = off (0) or close the memory at any time by playing a controller #87 = on (127).  Just make sure to close it when finished to prevent possible problems during performance.