Greetings all,  I recently had the opportunity to examine and use a
T-100 Red Welte Test roll that was made by Edwin Welte sometime after
WW2.  There were also handwritten instructions, in English (by Welte)
before each test.  The instructions were basically the same as the
instruction sheets that have been floating around for the T-100 rolls
now for some time.  Most of the other T-100 test rolls I have seen do
not have the following enhancements.

The interesting thing about the roll was the first test, the one that
verifies each note plays.  About a half inch after each note punching
there was a smaller hole, and another half inch later an even smaller
hole.  As I used the roll to check the piano and mechanism, the purpose
of the smaller holes became evident.  The first small hole was to cause
the pouch to inflate but not allow enough transfer of vacuum to make
the note strike.  The hammer would move up to the strings but not
sound.  The second smaller hole was to insure that the pouch didn't
inflate at all.  It was a fail safe test.

I had a T-100 test roll that Mike Kitner made about 20 years ago,
which also had the same series of large and small holes; I didn't get
it at the time.  The smaller test holes can also be used to set the
smoothness of each note, at low vacuum levels.  Therefore, if all notes
sound the same amount (a subjective judgement at best), then the first
set of small holes could be used to insure that the minimum intensity
level (if you will) is correct for each note.  The hammer moves, but
doesn't hit the string.  This also goes a long way to insuring that the
stack is regulated to the action and that the action is functioning
correctly.  The bane of all reproducing pianos is that they generally
are incapable of playing much below mezzo-piano, due to bad regulation
and sluggish actions.  This system of holes seems to go a long way to
correcting that problem.

I would be curious to know what the ratios of the hole sizes are.
Mike Kitner, do you remember the diameters of the punches you used?
I would also suggest that one of our brethren that are seeking ways to
get the other reproducing systems playing softy and evenly, modify a
test roll with the ratios provided, then try it out on a Duo-Art or
Ampico A.

Regards,

John McClelland