Robbie asked if I knew how to make rolls sound like Waller and others.
In reply I would say that I certainly know how to copy Waller's playing
from his records, and cutting that information into a blank paper roll
is a relatively simple business.

However the roll would sound awful; sure, it would activate the right
notes on the piano but there would be no light and shade, nor would
there be any of the subtle pedal control of the live performer.  At one
time I used to cut sustaining pedal slots into my rolls but found that
the large bellows diverted too much power from the striker pneumatics,
thus weakening loud chords and and blurring melody and harmony.

Instead I lengthen the holes of any notes I want to sustain, that way
the amount of vacuum in the stack is optimised.

After years of transcribing records made by many of the jazz greats
(Fats Waller, Teddy Wilson, Art Tatum, James P. Johnson etc. etc.)
I have come to the conclusion that it is impossible to make a perfect
carbon copy of any of them on a piano roll.  After removing their
mistakes (yes, every pianist makes them!) and generally tidying up
a recording, the very best that can be achieved is a convincing
impression of a given artist.  I toyed with the idea of including all
mistakes on the roll, but was concerned that my customers might think
that I had made them!

Nobody, but nobody, can make an absolutely faithful note-for-note
transcription of a jazz piano recording.  I can pick out chord changes
and melody lines quite well (ask Robbie!), however there is no way to
establish with any certainty which inversion of a chord is being used.
I have to trust my ear and use whatever sounds most attractive, but
it might not be the same inversion employed by the pianist on the
record.

I always inform my roll customers of my source material -- that way
they are able to make comparisons for themselves and judge just how
close I got to the original recordings.  Above all I try not to
sacrifice musicality for the sake of exactitude; if something on the
recording does not work on the roll then I will alter it.

Most of my adult life has been spent analysing pianistic techniques
for the purposes of piano roll production, yet the pleasure I derive
from listening to these wonderful pianists remains undimmed.  It is
still a magical, wonderful experience for me -- even though I now know
how they did it.

John Farrell