In 1904 Welte could and did record full expression while the master
roll was being marked.  The Welte-Mignon, or "Red" Welte, system did
record not only the note itself but also the initial strike intensity,
the depth of the key stroke and the length of the note being played.
All this simultaneously for each note as it was being played by the
artist.

Not like as went on at Aeolian with the notes only being recorded but
with some frantic tech sitting at a console with two dials to twist,
one for melody intensity and one for accompaniment intensity.  Then,
similar to Ampico, an army of people sanitized the recording to the
point with some rolls that the true desire of the pianist went out the
window.  Perhaps that is why the Welte-Mignon rolls sound so natural.
They most carefully did their best to preserve the true feeling the
artist was putting into the recording.  Only wrong notes or pedaling
were edited.

Only with reproducing pipe organ rolls could the expression, stops and
notes be recorded at the same time in a recording machine that could
actually punch the roll as it was being played by the musician.  Being
fully digital, electrical on-off signals are all that are needed for
organ recording, unlike the analog expression needed for piano music.

Jim Crank