Following recent discussions about this system, I was asked by Paddy
Handscombe to check the spacing of notes across a Triphonola roll.
The system controls expression with additional perforations outside
the normal 88-note scale.

Dan Wilson said in MMD 09.07.00 that these additional tracks are
narrower with smaller perforations than the standard 9 to the inch.
This is not the case; the measurements show that all the tracks are
spaced 9 notes to the inch on an extension to the normal scale.
This includes the double-width Themodist-style 'snakebite' accent
perforations, which occupy two tracks.  All perforations are of the
same size, including the accent holes.

The scale has, reading outwards from the lowest 88-note scale bass
note:

  2 tracks for bass theme
  1 track for sustaining pedal
  3 tracks for expression controls (Theme MF-FF; Accompaniment P-MF;
    Soft pedal)

Reading outwards from the highest treble note, the scale is:

  2 tracks for treble theme
  4 tracks for expression controls (Accompaniment acceleration;
    Theme P-MF; Theme acceleration; Accompaniment M-FF)

In other words, there are 6 additional columns of perforations outside
the normal 88-note scale at each end of the tracker bar, making a total
of 100 tracks across the roll.  The sustaining pedal is in the
conventional position (which is why I've not listed it as an expression
track).  Take off the expression tracks and you have a standard
Themodist-style roll.

It would not be possible to fit any further tracks across the roll.
This suggests that the system was designed to use all the possible
9-to-the-inch tracks without losing any notes to the expression system.
Very ingenious!

According to Paddy Handscombe, the tracker bar perforations are of
various heights, and Paddy will no doubt give more detail in due
course.  The assignations of the tracks above are what we discussed
on the phone last night.  The soft pedal is a lock & cancel system with
two holes vertically, a long perforation turning the pedal on and a
single punch turning it off.

Julian Dyer