My commentary is written between the lines below.  I hope that is helpful.

 [ I wrote back to Allen Ford with some T-98 information whereupon
 [ Hans-W. Schmitz replied to both of us.  -- Robbie

>> I therefore ask what is the tracker bar scale of the T-98.

> 1. The T-98 scale is given in this book:
>
> Peter Hagmann: Das Welte-Mignon-Klavier, die Welte-Philharmonie-Orgel
> und die Anfänge der Reproduktion von Musik, (C) 1984 Verlag
> Peter Lang AG, Bern [Suisse]
>
> Appendix 11, page 211, Blockskala zum Welte-Mignon-Klavier T-98:
>
> 1. Bass sFz off (a long perforation causes Rewind)
> 2. Bass mF
> 3. Sustain pedal
> 4. Bass crescendo
> 5. Bass sFz on
>
> 6 to 93: playing notes (88 notes)
>
> 94. Treble sFz on
> 95. Treble crescendo
> 96. Soft pedal
> 97. Treble mF
> 98. Treble sFz off

and that is correct.  The tracker bar scale is also in the
Dangel/Schmitz catalogue as mentioned in MMDigest 130414.  There we
wrote "1. Bass forzando forte" and "5. Bass forzando piano", etc.,
as written by Welte.

Additional information is:  Playing notes are from A-C, and:
Welte-Pianon T-98 pianos read only 80 notes, No. 6-8 and No. 89-91 are
not used.  No. 92 (long hole) is motor switch off and used for Pianon
rolls of the 9000 and 9500 series after each musical piece.  No. 93 is
Rewind.

Some extremely rare T-98 Pianon rolls (the word "Schlagzeug" is stamped
on the labels) have an additional percussion punching: No. 6 Mandolin,
No. 7 Cymbal, No. 8 Bass drum, No. 89 Small drum (snare?), No. 90 wood
block, No. 91 Tom-tom.  (Information from a test roll.)

A Pianon piano with additional tubings to the missing percussion case
on top is known.  No complete instrument is known, but a flyer shows
a picture of a "Welte-Jazz-Schlagzeug".


> 2. This note appears in Appendix D, page 943, of the book by Charles
> Davis Smith: The Welte-Mignon - Its Music and Musicians, (C) 1994 AMICA
>
> "Some T-98 Green pianos have been found with 80-note stacks.  Also,
> since T-98 rolls were made from 80-note T-100 masters, most do not
> contain 88 notes.  Additional notes were added to a small percentage
> of T-98 rolls."

Or: all 88 notes were recorded from 1924 on, when Welte introduced the
T-98, or even earlier, when they decided to built the T-98, and omitted
some notes in the T-100 rolls.  Quite a lot of T-98 rolls with light
music use the complete 88-note scale.


> Discussion:
>
> a. The T-98 system was developed especially to meet the market demand
> for pianos that would play popular music rolls perforated at nine
> holes-per-inch.  The T-100 system played only the proprietary T-100
> format rolls.  (Just as today, it was the young people who were buying
> recorded music in the 1920s and they wanted contemporary songs from
> abroad, not classical music.)
>
> b. I would trust data provided by Mr. Schmitz.  He is an expert Welte
> technician with many years experience restoring and regulating Welte
> instruments.  I would view with suspicion the technical data offered
> in a "coffee table" book published by a museum.
>
> c. Motor shut-off is not controlled at the T-98 tracker bar.

See my notes above for hole 93.  But all Mignon and Pianon pianos have
a take-up spool with a groove.  When the roll paper gets off the spool
after rewinding, a lever falls into the groove and switches off the
motor pneumatically.

1. See above.

2. The perforations on holes 1, 5, 94 and 98 are always very short.
A perforation on hole 1 closes also a small bellows very slowly, and
with a complete closure by a long hole affects a lever opening a
[pallet valve] hole (instead of a hole in the tracker bar).

3. The tracking of the T-98 rolls is not identical to normal 88-note
rolls, probably caused by slightly thicker flanges.  The difference is
2/5 to 4/5 between two lines, and the automatic tracking device is not
regulating that sufficiently.  But with a slight other adjustment it
plays the standard rolls.

Some Mignon T-98 are "combined" instruments to play T-98 rolls or all
other standard 88-note rolls.  Some are with, others without pedals,
but always with a 4-position switch to play 88-note rolls with or
without Themodist/Solodant or Welte rolls with accentuation by hand or
automatically.  These compensate the tracking problems and switch over
between the Welte bass-treble separation (same as in T-100 = between
F-sharp and G) and the standard split.

Kind regards,
Hans-W. Schmitz
Stuttgart